Method and apparatus for stripping voltammetric and potent iometric detection and measurement of contamination in liquids

Abstract

A system for measuring the presence and concentration of electro-active species in a liquid solution. The system comprises a preparation module, a potentiometric module and a voltammetric module. The preparation module is adapted to prepare and isolate the contaminants of concern in a liquid sample into its electro-active form. The potentiometric module is coupled to the preparation module and adapted to gather environmental metrics of the liquid sample. The voltammetric module is adapted to receive the sample from the potentiometric module or preparation module and identify and determine a concentration of electro-active species.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Application No. 60/299,514, filed on Jun. 19, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to water processing and treatment, and more particularly, to the determination of electrochemically active ions in an aqueous solution.

[0004] 2. Brief Description of Related Developments

[0005] In recent years there has been increasing demand for continuous real-time or near real-time monitoring of solution composition. Of particular interest are voltammetric detectors which measure the current response at given applied potential. Voltammetric detectors have applications which cover many fields and include for example environmental monitoring, process control, and biomedical monitoring. In particular, voltammetric detectors have found applications in heavy metal monitoring, clinical chemistry and as detectors for use in high-performance liquid chromatography HPLC.

[0006] Many other techniques are also currently available for the detection of contaminants. The development and improvement of these techniques has become a major focal point of analytical science because of the growing need to detect very small amounts of contaminants which adversely affect the environment. For example, mercury is regarded as a very toxic heavy metal, and its presence in soil and waterways represents a considerable health hazard. Government agencies throughout the world are increasing restrictions on the release of mercury to the environment. In some countries, a legislated limit of 2 parts-per-billion in drinking water has been enforced. Other potentially hazardous metals like lead and cadmium appear to be receiving the same scrutiny. The United States Environmental Protection Agency is lowering the allowable level of arsenic from 50 parts per billion down to 10 parts per billion or perhaps as low as 2 parts per billion in drinking water and in discharge permits.

[0007] The most commonly used methods for detecting various trace contaminants are atomic absorption (AA), inductively coupled plasma atomic emission (ICP-AE), and mass spectroscopy (MS). Each of these methods is suitable for trace analysis of nonmetals, metalloids, and metals, for example mercury in a laboratory setting. However, they often require well-controlled experimental conditions, expensive instrumentation, and frequent maintenance and calibration. Moreover, these methods usually require lengthy sample preparation, especially when other interfering elements or impurities are present in the sample under investigation. For these reasons, the methods mentioned above are not particularly well-suited for rapid analysis in the field or on-site in a treatment plant. Other methods which are sometimes suitable for contaminant detection and analysis in the field include X-Ray Fluorescence (XRF), colorimetry, and ion-selective electrodes (ISE). Special mention is made of XRF, which is used in the field because of its suitability for simultaneously detecting many contaminants without substantial sample preparation. However, the detection limits for this method (about 30-100 ppm) is not low enough for accurately determining very low levels of metals like mercury (2 ppb). Moreover, XRF is very dependent on the nature of the environmental sample. For example, if one is running a mercury analysis on both a soil sample and a plastic sample, a separate calibration curve must be prepared for each. Colorimetric techniques can be complicated and time-consuming. Also, such techniques are often very specific, e.g. selective to only one type of mercury complex, unlike the proposed invention which is sensitive to all electro active species of an element.

[0008] One significant disadvantage of most commonly used methods in the detection of trace contaminants is the difficulty of performing analyses of highly complex samples, such as ocean water. In complex solutions there can be a wide variety of elements with concentration levels much higher than the contaminants of concern which often interfere with the accurate detection and quantification of trace elements. The concentration difference between the contaminants of concern and the other impurities in the water precludes the successful application of many analytical tools and techniques. The analysis of complex waters, such as ocean waters, by common methods requires the extraction of the contaminant of concern from the sample before an accurate analysis is made, e.g. in ocean water, one would have to separate the salts from the ions to be analyzed. One distinct advantage to the proposed voltammetric based system is that the effect of interference is minimized with comparatively little to no sample preparation required. Presently, many common methods frequently require extensive sample pretreatment to determine low impurity levels of highly complex samples. Consequently most analytical determinations are made off-line in a conventional laboratory setting.

[0009] Voltammetric detectors offer considerable advantages in terms of sensitivity and selectivity over other techniques mentioned above. Stripping Voltammetry (SV) techniques cathodic and also anodic, as well as potentiometric analysis (PA) have long been used in trace analysis. In stripping voltammetry, the electroactive species in the sample are first pre-concentrated on the working electrode surface using a controlled potential or potentials. Once the ions are electrochemically collected on the face of the working electrode, the potential is varied to strip the material from the electrode surface. The current used and produced while stripping the material from the electrode surface is proportional to the concentration of the electro-active species in the sample. Electrodes for SV comprise a working electrode, reference electrode (usually Ag/AgCl), and an auxiliary (counter) electrode, usually platinum or graphite. The system and process of the subject invention is designed to analyze samples with complex matrices, and the system is designed to eliminate any possible interferences.

[0010] Thus, prior art systems are mostly for laboratory use, labor intensive and require considerable supervision by skilled personnel in order to determine low levels of contaminant concentrations. Furthermore, conventional techniques are impaired by interference caused by high concentrations of other species present with the impurities. If interference is expected in conventional techniques, it is often necessary to alter the electrolyte by the addition of suitable substances to avoid interference.

[0011] U.S. Pat. No. 4,804,443, entitled, “METHOD AND APPARATUS FOR THE DETERMINATION OF ELECTROCHEMICALLY ACTIVE COMPONENTS IN A PROCESS STREAM”, to Newman, et al., is effective in analysis of samples with high concentrations of impurities and high possibilities of interferences influence of sample matrix. The method comprises the steps of providing a sample in which the components are contained, and depositing the components onto a working electrode, altering the environment of the working electrode so that it is immersed in a supporting electrolyte by effecting a matrix exchange and stripping the deposited electrochemically active components from the working electrode into the supporting electrolyte. While this technique decreases interference problems, it significantly complicates the design of the system and algorithm of measurements. The method and apparatus utilize a mercury drop electrode, and the stability and size of the hanging mercury drop electrode are critical for overall accuracy and precision of the analysis. Also, additional steps of removing the sample from the cell after deposition of electrochemically active species and pumping electrolyte to the cell may cause unwanted changes on the electrode surface, which decreases the accuracy and precision of the analysis, thereby increasing the time of the analysis. The system and process of the subject invention has a more innovative, capable and simple design. Different electrode types may be employed, e.g. gold plated electrode, in order to increase the sensitivity and selectivity of the analysis. The measurement cell design in the subject invention provide for significantly more stable electrodes that, when used with the proposed analysis technique will result in lower detection capability and faster analysis times which are critical to the on-line process control applications intended for this system.

[0012] The system and process described in U.S. Pat. No. 4,626,992, entitled, “WATER QUALITY EARLY WARNING SYSTEM” to Greaves, et al., is confined to the detection and identification, via video monitoring techniques, of living organisms in sources of water supplies. The computer includes two software programs, one is responsive to the measurements by the sensors to derive a set of prediction parameters corresponding to the statistical distribution of the expected movement patterns of the organisms. The other software program is used for analyzing the organisms movement and comparing the observed movements with the set of prediction parameters, and for initiating the generation of the warning message when the organisms observed movements do not correspond to the prediction parameters. The system and process of the subject invention is designed to detect the presence and/or concentration of ions, compounds or elements other than living organisms in a solution. The system is designed to automatically measure, calculate, and report the concentration of the contaminant species. The methods of potentiometry and stripping voltammetry will be used for measurements; calculations will be accomplished with hardware and software, and the reporting will be done using the internal software. The method provides a highly objective and quantitative assessment of water characteristics from which to base early warning alarms from.

[0013] U.S. Pat. No. 4,723,511, entitled, “CONTINUOUS MONITORING OF WATER QUALITY” to Solman, et al., describes a slow monitoring system for rapid feed forward and feedback data mechanism to manage a modern water treatment system. The purity and presence of contaminants is monitored by the reactions of a fish in a tank of water. In contrast, the present invention provides fast quantitative on-line analysis using a highly accurate, automated, and sensitive Stripping Voltammetric technique.

[0014] U.S. Pat. No. 5,646,863 Morton, entitled, “METHOD AND APPARTUS FOR DETECTING AND CLASSIFYING CONTAMINANTS IN WATER” describes a system which samples, detects, measures, and reports, in near-real time, the presence of contaminants and thereby provides users with the ability to continually monitor conformance of water with established health and safety standards. This apparatus has ample measurement sensors selected from group consisting of pH sensor, temperature sensor, metal sensor, organic sensor, radiation sensor and biosensor. Stripping electrochemical sensors for measuring metals in parts per billion concentrations is claimed. The system and process of the subject invention measures ions, elements and compounds of metals, nonmetals and metalloids. The Morton system determines the voltammetric analysis oxidation current, which is related to the concentration in a sample. The subject invention measures both oxidation and reduction current as a derivative of the current, which is proportional to concentration of analyte in the sample. The invention increases both the accuracy and precision of the analysis. The sample preparation procedure of Morton uses selective oxidizing or reducing of the sample in the presence of acid. In the subject invention, the sample preparation procedure uses a more universal approach to increase accuracy, selectivity and sensitivity of the analysis, that also includes the selective addition of organic or inorganic acid, base, salt, and chelating agents depending on the characteristics of the sample stream. Likewise each sample preparation procedure will be enhanced, if necessary, by cathodic or/and anodic treatment of sample with or without the addition of reagents depending on the requirements of the analysis. The purpose of the proposed sample preparation in Stripping Voltammetry technique is to convert the analyte to a specific electroactive form, and preparations may include, but are not limited to change of the oxidation state of the analyte, dissolving of the analyte, formation of new complex compounds with analyte, and oxidation of organic compounds, etc. Therefore, the present subject invention has markedly improved the state of the art in Stripping voltammetry by lowering the detection limit from low ppb, to 5 ppt (parts per trillion), introducing a more selective sample preparation approach, and employing a more accurate analysis system of measuring both oxidation and reduction current as a derivative of the current to determine the concentration of analyte in the sample. In addition the present invention has significantly improved the integrated on-line process control capability described in Morton system, based on a flexible “feed forward” process control approach, the innovative software, and the alarm and system manipulation capabilities designed into the system, e.g. monitoring of water treatment system processes with the ability to notify plant personnel of alarm conditions as well as invoking system contingency operations such as the case of treatment malfunction, whereby the present invention will control the activation of valves and redirection of treatment effluent into holding tanks.

[0015] U.S. Pat. No. 4,300,909, entitled “PROCESS CONTROL” to Krumhansl, relates to methods and apparatus for measuring the chemical state of a fluid and physical state of both the fluid and an apparatus for treating it. It provides that information to an algorithm solving apparatus, and accomplishing process action in response to signals from the algorithm solving apparatus. Krumhansl is related to a swimming pool water treatment application. The process control includes functions of measuring the state of contaminants in a fluid and the interaction between the data and the apparatus for treating it by furnishing that information to an algorithm solving apparatus to accomplish functional responses. However, the present invention incorporates both feed forward and feedback control signals to the process management system, as well as affecting a number of automatic electrical and mechanical responses, as it archives data for visual inspection and analysis, which goes beyond the capabilities of this invention.

[0016] U.S. Pat. No. 5,292,423 of Wang, entitled “METHOD AND APPARATUS FOR TRACE METAL TESTING” is limited to microliter samples measurements for metal concentration using mercury-coated screen printed electrodes. The present invention measures a wide range of elements, metals, metalloids, and nonmetals and their derivatives, using different electrochemical methods, such as using ion-selective electrode and voltammetrically using solid state graphite electrodes. The subject invention takes the integrated system analysis beyond the capability of the Wang system by automatically calculating concentrations and multiple water characteristics, preparation of reports, and managing outside pumps and valves.

[0017] U.S. Pat. No. 5,873,990 to Wojciechowski, entitled “HANDHELD ELECTOMONITOR DEVICE” the portable monitor is a microprocessor based instrument designed to conventionally and rapidly measure various analytes in environmental and biological samples. The system uses battery or DC power. Unique electronic, microchip configurations were developed for the device to make it portable, low-cost, safe and simple to operate the instrument. The instrument has a small size, and the analysis is done on a manually taken sample. Calibration of the device using calibration strips is proposed. The colloidal gold electrode is applied for electrochemical measurements. The device is developed for metal analysis. The subject invention is designed for measurements in flow, the sample is automatically taken, automatically prepared, automatically reported to user(s), and the warning system is regularly integrated into a larger system to monitor contaminant values and regulate pumps and valves and alarm states.

SUMMARY OF THE INVENTION

[0018] The present invention is directed to a system for measuring the presence and concentration of electro-active species in a liquid solution. In one embodiment, the system comprises a preparation module, a potentiometric module and a voltammetric module. The preparation module is adapted to prepare and isolate the contaminants of concern in a liquid sample into its electro-active form. The potentiometric module is coupled to the preparation module and adapted to gather environmental metrics of the liquid sample. The voltammetric module is adapted to receive the sample from the potentiometric module or preparation module and identify and determine a concentration of electro-active species.

[0019] In one aspect, the present invention is directed to a method for detecting and identifying contaminants in liquids. In one embodiment, the method includes measuring environmental properties of a liquid sample taken from a liquid source and preparing the sample into its electro-active form. A concentration of contaminants in the sample is identified and determined by a stripping voltammetric process.

[0020] In another aspect, the present invention is directed to a water treatment system. In one embodiment the system comprises a first system and a second system and a water treatment system between the first and second system. The first system measures the presence and concentration of electro-active species in a liquid solution in an upstream location from the water treatment process. The second system measures the presence and concentration of electro-active species in a liquid solution in a downstream location from the water treatment process. The first and second systems are adapted to communicate sample characteristics to an independent treatment system adapted to control the treatment and processing of the contaminated water.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein:

[0022] FIG. 1 is a block diagram of one embodiment of a system incorporating features of the present invention.

[0023] FIG. 2 is a schematic diagram of one embodiment of a system incorporating features of the present invention.

[0024] FIG. 3 is a schematic diagram of one embodiment of a system incorporating features of the present invention.

[0025] FIG. 4 is a block diagram of one embodiment of a system incorporating features of the present invention.

[0026] FIG. 5 is an exploded perspective view of one embodiment of a preparation module incorporating features of the present invention.

[0027] FIGS. 6A, 6B and 6C are a flow chart illustrating one embodiment of a method incorporating features of the present invention.

[0028] FIG. 7 is block diagram of a water treatment system incorporating features of the present invention.

[0029] FIG. 8 is a block diagram of one embodiment of an architecture that can be used to practice the present invention.

[0030] FIG. 9 is an illustration of an exemplary system data display window for a system incorporating features of the present invention.

[0031] FIG. 10 is a block diagram of one embodiment of a system incorporating features of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(s)

[0032] Referring to FIG. 1, a block diagram of a system 10 incorporating features of the present invention is shown. Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used.

[0033] The system 10 generally comprises a highly advanced, sensitive, and responsive system of sensors and control hardware and software for the monitoring and control of contaminant flow through a treatment system.

[0034] As shown in FIG. 1, in one embodiment, the system 10 generally comprises a potentiometric module 12, a preparation module 14, and a voltammetric analysis module or cell 16. The system 10 is generally adapted to draw a sample 30 of fluid, such as for example water, from a source 2 and process it through the system 10 to measure the presence and concentrations of contaminant species in the sample. The system 10 can also include a sampling unit or pump 32 that is adapted to draw a sample 30 from a source 2 through an inlet tube or connection 18. In alternate embodiments, any suitable device can be used for introducing the liquid sample into the processing system.

[0035] The liquid sample 30 travels between the various modules via for example, interconnecting hydraulic lines 17, 19, 21 and 23. Pumps (not shown) can be used to move the fluid sample through the system. In alternate embodiments, the system 10 can include other such suitable components for rapidly and continuously conducting a variety of analyses on electroactive elements in aqueous solutions. It is a feature of the present invention to integrate and manage data from electrochemical and ion selective analysis in an integrated treatment system and incorporate sensor data with electrical and mechanical interfaces to manage the contaminant flow in treatment processes. The present invention generally comprises a fully automated analysis system, that will take a sample, analyze it by ion selective electrodes, prepare the sample for stripping voltammetric analysis, prepare the voltammetric sensor for analysis, analyze the sample, calculate concentration levels, transfer results to the users and a system process controller, manage outside pumps or valves, and give warning signals.

[0036] As shown in FIG. 1, a sample pump 32 will take a sample (aliquot) and deliver it to the potentiometric unit 12. Preferably, the sample pump 32 takes the sample or samples continuously. The speed of flow may be varied in the range from 1 mL up to 50 mL per min. In one embodiment, the sampling unit 32 can include filters (not shown). The sample 30 can be filtered to protect the system 10 as required. The size and quantity of the filters in the sample pump 32 will vary depending on the purpose of the analysis. The speed of the sample intake may be varied, either automatically or manually.

[0037] The sample is transferred to the potentiometric module 12 for potentiometric analysis and temperature measurement of the sample. A maximum of five potentiometric measurements of the aliquot can be conducted using a similar number of commercially available potentiometric electrodes 15. The potentiometric module 12 can include at least one port on electrode 15 for remote temperature measurement. The temperature of the initial sample can be measured in the source stream 2, using a commercially available thermistor 34, that will be connected to a temperature sensing device in the potentiometric unit 12 via a cable 22 or other suitable means. Different composition of ion-selective electrodes in the potentiometric module 12 may be selected, depending on requirements. In an embodiment of the present invention where the system 10 is computer controlled, all potentiometric and temperature measurements can be controlled by the “Parameters” window of the embedded software of the computer system.

[0038] The potentiometric module 12 is generally adapted to gather and evaluate environmental metrics that can be time correlated with the characteristics of the samples 30 drawn by the system 10. The potentiometric module 12 generally includes one or more ports 15 for attaching IEEE compatible ion selective electrodes and sensors. Some of the electrodes can be adapted to measure characteristics of the sample drawn into our system. Other sensors can be connected with the system 10 through one of the ports 15 and then remoted to the water source 2. Examples of these sensors can include flow meters and temperature sensors. The information gathered from these electrodes/sensors can then be correlated, with data from the voltammetric measurements to give a full set of vital signs for that sample.

[0039] In one embodiment, the potentiometric module 12 can include up to five connections 15 for ion selective electrodes to measure specific characteristics in a holding cell or connection of other sensors. These sensors can include sensors such as for example a temperature probe or sensor 34. The sensor 34 can be connected via a suitable connection means 22 to the potentiometric module 12 and be adapted to be physically inserted into the sample or water source or elsewhere 2. For example, the sensor 34 could be inserted into a pipe stream of the water source 2 or hung off a buoy in the water source 2. The connection means 22 could include for example, a physical wire connector connection such as a cable, or a wireless optical or RF connection or coupling.

[0040] The sample is then transferred to the sample preparation module or cell 14. Once the sample is in the preparation module 14, the sample is mixed with a preselected electrolyte solution. FIG. 2 provides an illustration of how a standard solution 124 can be introduced in the preparation cell 114. The sample preparation module 14 shown in FIG. 1 is generally adapted to process the species to be analyzed into an electroactive form and treats a sample 30 flowing into the module 14 with a reagent and then electrically stimulates the sample. During the process of preparation, a number of things take place including stripping organics away, dissolving some possible particles of the contaminant of concern, any oxidizing and eliminating unwanted elements to minimize interference issue. The preparation module 14 receives the sample from the potentiometric module 12 via an inlet 19 controlled via pumps. The inlet 19 could include a controlled valve. In one embodiment, the system 10 can include a system of pumps and valves, such as for example, a hydraulic system.

[0041] In one embodiment, referring to FIG. 5, the preparation module 514 can be divided into two parts or sections 71, 72, with a semi-permeable membrane 80 separating the two sections 71, 72. The semi-permeable membrane 80 is generally an ion exchange membrane adapted to facilitate the electrochemical oxidation of the sample and provide a closed circuit for electrical current, and so the solutions from both compartments of the module 514 will not mix with each other. Each portion 71, 72 of the module 70 can include an electrode, 77, 78. The electrodes 77, 78 can comprise carbon electrodes and are part of the sample preparation process. In the electrochemical preparation of the sample, the two graphite electrodes 77, 78 can be used in two chambers separated by the semi-permeable membrane. The voltage applied during the electrochemical preparation is automatically controlled by the system and is preprogrammed by the operator.

[0042] The sample flowing into the sensor 77 via inlet 73 is treated with a reagent and then electrochemically to convert the analyte to an electroactive form. The preparation will increase the conductivity of the solution, convert non electro-active species of the analyte to electroactive forms, and decrease interference from other elements in the sample 30. The electrolyte solution added to the sample, may consist of different reagents such as acid, base, salts, organic and inorganic chelating agents. The flow rate of the reagents may be automatically or manually varied as they are added to the sample. If necessary, the second part of the additional sample preparation procedure may include an anodic or cathodic sample preparation procedure of analyte at specially regulated voltages. This step speeds up the processes of converting non electro-active species of the analyte to electroactive forms, and decreases interference, thus increasing the effectiveness of sample preparation.

[0043] In one embodiment, referring to FIG. 5, the untreated sample flows in via tube 73 and the reagents are added to the inbound flowing compartment 71 of the preparation cell 70 via inlet tube 76. The treated sample then passes to the voltammetric cell 16 of FIG. 1, through outlet 74. The other side 72 of the cell 70 of FIG. 5, receives the waste from the voltammetric module 16 via inlet 79 and also draws waste material through the semi-permeable membrane 80 in the cell 70. The outflow of the waste side 72 of the preparation cell 70 via outlet 75 is then sent to the waste container 40 of FIG. 1. In one embodiment, reagents can also be added after the sample preparation module 114, shown for example in FIG. 2, particularly when filters are part of the sample preparation module. Referring to FIG. 4, the inclusion of filters in the preparation module or cell 412 that might be otherwise found at the beginning of the sampling module of FIG. 1 allows the sequence of modules to be changed to suit specific user requirements.

[0044] The voltammetric module 16 of FIG. 1 is generally adapted to identify and determine the concentration of the electro-active ions in the sample using different modifications of the voltammetric method. For example, referring to FIG. 2, a voltammetric analysis, such as stripping analysis, is performed in a measurement cell 116 having three electrodes, namely, an auxiliary electrode 144, a reference electrode 146, and a working electrode 142. The three electrodes are placed in the measurement cell 116 in spaced-apart arrangement and an electric potential is then applied across the auxiliary electrode 144 and the working electrode 146. The potential value is controlled versus the reference electrode (silver/silver chloride electrode). An electrochemical pre-concentration of the analyte on the electrode surface occurs. The following step is stripping off the pre-concentrated forms. As the potential on the working electrode is varied over a specific range, and at a specified time duration, a varying current flows through the working electrode 142 surface as a result of oxidation/reduction reactions on it. The position of the signals on voltammograms will be used for identification of the ions, and the magnitude of the signal will be used for determination of the concentration. A voltage meter 156 and current meter 154 shown in FIG. 2 can be used to monitor the voltage/current change.

[0045] The voltammetric module 16 will determine a concentration of the species of interest. Actual contaminants such as arsenic and others can have multiple types of ions associated with it. These ions will have different characteristics. For example, arsenic typically has a variety of As+3 and As+5 ions dissolved in the sample. One is much more dangerous than the other, but there is tremendous value in knowing the presence and concentration of each type. Most systems can only tell you the presence of total arsenic, but very few can identify only As+3 and As+5 and/or the total of both As+3 and +5. In the arsenic problem this is significant because treatment requires that all arsenic be converted into As+5 before it can be removed, and in the arsenic treatment industry this will be a big selling point for us. These different types of ions are generally called species, and the process that our system can perform is called speciation. It is a feature of the present invention to speciate electro-active ions.

[0046] The voltammetric module 16 of FIG. 2 is configured with at least one flow through cell. In one embodiment it comprises a ceramic/teflon block with a channel that directs the sample through the block and over the exposed ends of each of the three electrodes that are configured in a unique relationship to minimize electrical noise and maximize the current measurement of the stripping process. The pumps controls the rate of flow through the voltammetric cell, hence the volume, the system voltammetrically measures the concentration of the contaminant(s) of concern in “parts per billion” or more technically micrograms per liter. There are values on either end of each flow through cell and the electrodes can be integrated into the cell. FIG. 3 depicts an embodiment of the system with up to three individual flow through cells 151-153 for the purpose of system redundancy and increased mean time between maintenance, while FIG. 2 depicts an embodiment of the system with more detail of one flow through cell 116 and the configuration with the integrated electrodes.

[0047] In one embodiment, referring to FIG. 2, a system 100 incorporating features of the present invention can include a computerized device or system 250 for controlling the system 100. The system 250 can include a controller 251, such as for example a microcomputer or computer system adapted to manage and control sample 130 acquisition, sample preparation, sample flow, and sample presentation to the measurement cell 116, wave form generation, electrode plating, data acquisition, data processing, data evaluation, data visualization, data archiving, data reporting, process control, and alarm response. The control system 250 can be a microprocessor controlled system of sensors and control hardware and software adapted to monitor and manage contaminant flow through an aqueous treatment system.

[0048] The control system 250 is also adapted to control the sample, plating, reagent and standard solution pump work. Also, the control system 250 controls electrode modification operations, potentiometric measurements and potentials and times of electrode modification operation, sample preparation procedures, voltammetric measurements, sending the results to computer. The microprocessor receives the control parameters from the software program.

[0049] As shown in FIG. 2, in preparation for the stripping voltammetric analysis, the cell 116 should be properly prepared. The cell 116 can include a set 110 of three electrodes 142, 144 and 146. The electrodes 110 can include a working electrode 142, an auxiliary electrode 144 and a reference electrode 146. The choice of working electrode 142 depends on the type of analyte to be determined, and can be a specially modified graphite, gold, platinum, impregnated carbon or glassy carbon electrode. The auxiliary electrode 144 is a specially prepared graphite pressed into a polymer body, and the reference electrode 146 is a silver electrode pressed into a polymer body. The stripping voltammetric or measurement cell 116 will work at this time on the preparation of the working electrode 142. For some of the elements, the plating preparation of the working electrode is not necessary. In one embodiment, if plating preparations are not necessary, a special radial button “NO” in the “plating” section in the “parameters window” of a control system input/output display 252 (“I/O”) can be highlighted. If plating is necessary, the parameters of plating, such as potential and time of plating, should be shown on the “parameters window” of the I/O 252. During plating, a special solution from the plating solution chamber 120 will circulate through the stripping voltammetric cell 116. The plating solution composition varies from the type analyte that the system 100 is adapted to detect. Plating potential will be given to the working electrode 142 using a three electrode potentiostat scheme. Plating potential value and plating time may be varied by changing parameters of the “plating” section of the “Parameters” window in the computer 251. When the working electrode 142 is prepared, the plating solution will be pumped back to the plating chamber 120 and the prepared sample will go through the cell 116. The plating pump 121 will not work again, until new plating is required.

[0050] The system 100 starts a stripping voltammetric analysis, once it has taken a sample 130, filtered it 102, performed temperature and potentiometric measurements on the sample 130, initially prepared the electrodes 144-146, and filled the sample preparation chamber 114. The voltammetric measurements will be done using specially developed algorithms of stripping voltammetric analysis. At the beginning of each analysis the working electrode 142 will be cleaned by scanning linear potential from Edeposition to Efinal multiple times. The potentials and number of scans may be varied through the “parameters” window of the software program. Next, the deposition step will be conducted. The deposition step may involve one or two different potentials given for certain amount of time. All potential values will be given versus the reference electrode. The deposition potential and time of the deposition may vary by using the “parameters” window of control system 250. Throughout the deposition step, the sample 130 will flow through the cell and directly past the working electrode 142. The next step, the measurement step, will require a complete halt of all sample flow. All system pumps 121, 123, 132 and 175 will be turned completely off and all valves near the stripping cell 116 will be closed, and the cell 116 should remain filled with solution. After a predetermined waiting period, for example ten seconds, the potential on the working electrode 142 will be linearly scanned from Edeposition to Einitial at a preselected rate. A mathematical analysis of the current versus potential will be measured and a voltammogram of the result will be stored in the memory of the device, and displayed on the operator screen, and/or transmitted to a central data archival system.

[0051] In one embodiment referring to FIG. 2, the system 100 can include a container 122 with standard solution of analyte. After the previous step, a known amount of the standard solution will be added to the sample flow. The amount of standard solution added may be varied automatically through the “Parameters” window of the control device 250, or manually in the system. All measurements described above will then be repeated.

[0052] Two voltammograms of the sample, with and without standard additions, can then be recorded. In one embodiment, a window of the I/O 252 can have moveable boundaries which can be used to select a signal to measure. The control device 250 will find the minimum and maximum amplitudes of each curve in the area of two boundaries and calculate the maximum amplitude of the desired signal in specific units. The high of the signal of sample and signal of the sample with standard addition will be used for calculation of concentration using a specially formulated mathematical formula.

[0053] The system 100 is adapted to continuously analyze solution. This means, when one cycle of potentiometric measurement is completed, the next stripping voltammetric steps will be repeated.

[0054] In one embodiment, the system 100 will automatically compare the value of the stripping signal of the sample with a given value to determine if dilution is required. If the value is larger than a standard value, the system 100 can automatically use the dilution mode. In the dilution mode, the sample pump 132 will be used for pumping the diluting electrolyte. The reagent pump 125 will work as the sample pump. The dilution ratio may be changed by changing the speed of the pump through a “Dilution parameters window” of the I/O 252 or manually. The voltammetric measurement procedures above will be the same. In the calculations of the concentrations, a special dilution mode formula will be used.

[0055] After the sample is analyzed in the measuring cell 116, the solutions will be guided to the waste water section 141. In the waste water section 141, the water 140 may be collected in the container or bottle 141 or cleaned using special columns with adsorbents or ion-exchange resins.

[0056] The computer or control system 250 attached to the system will have a program for preparation of the reports. Data will be shown corresponding to the time of the analysis, and may be archived for further analysis.

[0057] The system 100 can also include alarms or warnings. If the contaminant concentration being monitored is greater or less than a predetermined value, the system 100 communicates to a controller to initiate alarms, redirects water flow into a holding tank, notifies key personnel, and provides signal inputs to system control software to affect contaminant removal processes.

[0058] The system 100 can also include a self test mode to be able to test key parameters to determine operational status.

[0059] Referring to FIG. 3, the voltammetric analysis module 316 can include up to three flow-through cells 151, 152 and 153 for voltammetric measurements. There are valves on either end of each cell 151-153, and the electrodes are integrated directly into the cell itself. The addition of the standard solution 148 and plating solution 180 (i.e. modification solution) are injected through the valves 161, 163 and 165 directly up stream from the flow cell. Having more than one cell allows for greater flexibility and time between servicing. In order to extend the time between system services, the system can be automatically selected to switch from one cell to another when the efficiency of one cell reaches a predetermined limit. The cells can also be changed manually by the operator, if necessary using the “start new cell” option in the “parameters” window of the users software.

[0060] The sample pump 170 shown in FIG. 3 will contain a pump connected to a specially designed electronics circuit. The speed of the pump 170 may be varied manually and automatically. The filtration of the sample 330 occurs through specially constructed filter unit 172. The combination of filters may be changed in accordance with tasks of the analysis. The potentiometric and temperature measuring unit 312 is adapted to conduct a potentiometric analysis of the sample 330 drawn using ion-selective electrodes. The potentiometric cell 312 contains a special chamber with ion-selective electrodes such as those shown in FIG. 5. The electrodes may be changed in accordance with tasks of the analysis. The electrodes are connected to a specially designed electronic circuit, which is managed by a microprocessor based controller. The potentiometric chamber 312 can also have a level sensor, which is connected to a controller and will give signal based on sample presence. The temperature sensor 334 determines the temperature of the sample 330 using for example a thermistor immersed in the original stream or container 176. The thermistor can be connected through an isolated electrical cord 322 to the special electronic circuit of the unit 208.

[0061] After potentiometric measurements in unit 312, the sample will go to the preparation module 314. The preparation module 314 is a two part chamber 158, 160 separated by a semi permeable membrane 159 similar to the exemplary preparation module 514 shown in FIG. 5. Referring to FIG. 3, the sample and necessary reagents will flow into the chamber 158, where the mixing occurs. The speed of pump 156 may be varied automatically and manually. Special design of the electrodes 77, 78 shown in FIG. 5 and connections will prevent contamination of the sample from connectors and provide hermetic isolation of the cell. Graphite electrodes, one in each part will be connected to an electronics circuit which will give potential from −10V up to 10V. The sample will be treated anodically or cathodically in accordance with a special algorithm. The algorithm or anodic/cathodic treatment of the sample can be controlled by the microcontroller and may be varied through the “sample preparation voltage” in the “parameters” window of a the software program. The reagent pump 164 additionally will be monitored by the controller. The speed of the pump 164 can be changed manually and automatically by changing “pump parameters” in the software window. The second part 160 of the preparation cell 314 will be filled by sample flowing back from the voltammetric cell 316.

[0062] As shown in FIG. 2, the voltammetric flow through cell 116 can contain three electrodes. The working electrode 142 can be a specially designed graphite electrode in a polymer body. The auxiliary electrode 144 can be a specially designed graphite electrode. The reference electrode 146 can be a silver wire in a polymer body. The electrodes 142-146 can be located in the voltammetric analysis cell and the cell 214 has a geometric groove through it, with the solution flowing through the groove. The groove can be any suitable dimension. In the preferred embodiment the groove can be approximately ½ millimeter (0.5 mm) in cross-width and ½ millimeter (0.5 mm) in depth, running down the middle of the flow through cell.

[0063] Referring to FIGS. 2 and 4, in order to prepare the working electrode 142 in the voltammetric analysis cell 116 for analysis, plating solution 120 is pumped in by means of the pump 121. The pump is monitored through the electronic circuit and the speed of the pump 121 can be changed manually or automatically. This can include changing pump parameters in the software program of control device 250. The speed of the pump 121 will be monitored by the system controller. The electrode surface is modified in accordance with a special algorithm and potentials/currents applied to the working, auxiliary, and reference electrodes 142-146 in the measuring cell 116 using a three electrodes electronics scheme. The algorithms of the applied potential/current are controlled by the controller. The algorithm of the electrode modification can be ordered through “plating parameters” of the “parameters” window.

[0064] The voltammetric measurement of the sample flowing through the cell 116 of FIG. 2 will be done in accordance with an algorithm which will be monitored by a micro controller and can be changed through a software window. The parameters of voltammetric measurements include changing the deposition potential from −2.5V to +2V, initial potential from −2.5V to 2V, final potential from −2.5V to 2.0V, time of deposition, linear scan rate can vary from 0.05V/sec to 1V per second, a quiet time 10 sec, type of linear-scan, number of cleaning scans from 1 to 50. Anodic and/or cathodic stripping voltammetric measurements will be available.

[0065] Referring to FIGS. 6A-6C, one embodiment of a method of stripping voltammetric measurements is shown. The initialization step (601) includes pre-concentration of the analyte on the surface of the electrode as given in the system parameters (deposition potential, time of deposition). The sample, which is prepared for analysis, will flow through the preparation cell 114 in this step. All pumps (164, 156 and 178 of FIG. 3) can be stopped and the valves of the measuring cell 116 will be closed. The sample will not flow through the cell 116, but the cell 116 will be filled with the sample. A linear change of the potential from an initial potential to a final potential is applied. At this step the current versus voltage curve will be registered. The electrode is electrochemically cleaned. Voltammetric measurements of sample with standard addition will occur. The standard solution pump 123 will be automatically turned on and voltammetric measurements described in previous part will be repeated.

[0066] In one embodiment, the microprocessor will send the results of the measurements to the memory of the computer 151. After this the new cycles of measurements will be done. The software program has special boundaries which will be moved by the operator to identify the peaks to be measured. The peaks should be identified only one time, since the position of the peaks are the same, the program will use it for the following calculations. If necessary, the boundaries may be moved. The program will find signal values (value between max and min current inside of the boundaries) and calculate the results using special formulas for standard addition method. The program will prepare reports and send it to memory

[0067] In one embodiment, the central controller 251 is a microprocessor device that is adapted to archive all system measurement data, analyze all data according to predetermined criteria, and then affect water management control measures accordingly. The central controller station 251 and I/O unit 252 allows an operator to review data from all measurement stations, as well as visualize, on a conceptual map, all systems under control. The central control 251 can include software that allows for storing, analyzing, and displaying all data collected throughout the system. It allows the import of data from other sources and the correlation of all data on printed reports and database files. The software can also incorporate a full featured statistics, spreadsheet, and graphics program for analysis and reporting purposes. The system controller 251 can direct the emergency response in the case of the systems detecting unacceptable levels of contaminants in the discharge through such actions as automatically notifying personnel, activating alarms, and redirecting water by switching valves. In one embodiment, the central control 251 is a WINDOWS™ based system. The system 250 can display certain “windows” to the user depending on the state of the system 100 and the particular application or measurement state.

[0068] The soft program can have one or more windows. One of them can be a “System Data Display” window such as that illustrated in FIG. 9. The window 902 can include blocks for pump parameters, potentiometric measurements parameters, sample preparation parameters, stripping voltammetric measurements parameters 908, standard solution 910 and plating parameters 918. Each block will show possible values of the parameters and allow the operator can select the values. If some values are not selected when the system is initiated, the program will prompt the operator to add any necessary parameters. The program can also have an “analysis results” window or block 912. In this window the voltammogram of sample and sample with standard addition will be shown, also the results of potentiometric and temperature measurement will be displayed. This window will have at least three sets of boundaries. The user will be able to move the boundaries to isolate the peaks which will be used to calculate concentrations levels. The software will have a special program for calculation of signal value, which is a value between max and min of the signal, and also the program for calculation of concentration using special formula for calculation based on standard addition value.

[0069] Referring to FIGS. 3 and 6, one method of operating a system 300 incorporating features of the present invention is illustrated. As shown in FIG. 3, the system 300 generally comprises a sample preparation module 314 that is divided into two chambers 158 and 160. The potentiometric measurement cell 312 receives the liquid sample 174 that has passed through the pump 170 and filters 172. One or more temperature probes 334 monitors the temperature of the sample 330 in the sample container 174 and in the potentiometric measurement cell 312. As shown in FIG. 3, the voltammetric module 316 can comprise up to three flow through measurement cells illustrated as 151, 152 and 153. A liquid waste module or container 340 is adapted to receive the sample after it has been processed and analyzed.

[0070] The system 300 shown in FIG. 3, includes a reagents module or container 162, a standard solution module or container 154 and an electrode modification solution module or container 185. The reagent 147 is pumped from the reagents module 162 via pump 164 to a valve 167 to be combined with the sample as it passes from the potentiometric measurement cell 312 to the first cell 158 of the sample preparation module 314. A standard solution 148 can be pumped from the standard solution module 154 via pump 156 to the first part 158 of the sample preparation module 314 via a valve 181. The electrode modification solution 185 can be added to any one of the flow through voltammetric measurement cells 151, 152 or 153, via valves 161, 163, 165, respectively. Valves 171, 173 and 175 can also control the flow of the electrode modification solution 185 back to the container 180 or to the second part 160 of the preparation module 314. A pump 178 is shown to pump the electrode modification solution 185 to and from the measurement cells 151, 152 and 153.

[0071] In one embodiment, referring to FIGS. 3 and 6, the system is initialized 301 and valves 161, 163, 165 and 171, 173 and 175 are closed. Valve 181 is opened. In an embodiment of a system 100 controlled by a control system 250 shown in FIG. 2, the program is started and all parameters of the analysis should be adjusted in the program and after that the program will await a signal from the microcontroller. The service person can go to the system and start the system by pushing a “start” button. For example, the microprocessor will close valves 161-165, and valves 171-175 . The microprocessor will send a signal to the software that the system has started and check the parameters of the pumps. The sample pump 170, standard solution pump 156 and reagent pump 164 will be started. The system will then pause (step 303) for approximately 5 minutes to allow sufficient time to fill all tubes (step 302) with solutions and to fill chamber 316 with ion-selective electrodes. In five minutes, the status of the level sensor in the potentiometric chamber 312 can be checked. If the level sensor shows that the chamber 312 was not filled, the system will wait again 5 minutes and after that will check the status of the level sensor again. In case of a failed signal, this cycle can be repeated for example 4 times, after this a warning sound signal and sign to check the sample pump and level sensor on potentiometric chamber can be sent. Also, a warning signal is sent to the panel of the device 250 to flash a lamp. If the system is not stopped at this moment, manually or through the computer, the system will proceed to the next step. The same step will proceed if system has a positive signal (the potentiometric chamber is filled). In this step, the system will identify if the potentiometric or temperature sensors are necessary. If yes, the system will take first measurements, to be sure that signals from the sensors exist. If signals do not exist, or are out of range the lamp on the device panel will flash and a warning sign “check potentiometric sensors and/or temperature sensors” will appear. The device will then proceed to the next step. If signals are acceptable, the system will proceed to the same next step. The microcontroller will check if modification of the working electrode in the voltammetric flow through cell is necessary. If it is necessary, the microcontroller will start the pump 178 of the modification solution 185, also referred to as the plating solution. At the same time the voltage parameters of the modification and time duration of every voltage will be checked by the microcontroller. The microcontroller will remember both times and voltages. When the first time is over, it will go immediately to the second time. When the timer shows that the second time is over, the microcontroller will stop pump 178, stop pump 156, open valves 161-165 and 171-175 and start voltammetric measurements. The cycle of voltammetric measurements include starting the cleaning of the electrode from EInitial to EFinal, then a preconcentration step. The preconcentration step will have two potentials available EDeposition and EInitial. After preconcentration is finished the microcontroller will proceed to the next step, a “quiet” step. At this step, the potential E initial will be kept on the working electrode, but all pumps (170 and 164 should be “off”, and pump 156 is “off” already from the previous step), the valves 161-165 and 171-175 are also off. After 10 seconds of quiet time, the linear scan of the voltage from EInitial to EFinal will be done. The current versus voltage will be recorded and stored in the memory of the microcontroller. Then the valves 161-165 and 171-175 will be opened and pumps 170, 164 and 156 will be “on” with the speed of each shown on the I/O 252. The cleaning of the working electrode from EInitial to EFinal will be done and the whole measuring process will be repeated. The second voltammogram will be sent to the computer. At the same time the potentiometric measurements will be done and sent with the second voltammogram or with two voltammograms. So, with this algorithm the potentiometric measurements will be done with the same frequency as voltammetric measurements. When all information is sent to the computer the microcontroller will stop pump 156 and the process of stripping voltammetric measurements will start again. At the same time the microcontroller will monitor the efficient life for each of the flow through voltammetric measurement cells. When the efficiency of each voltammetric flow through cell reaches a predetermined level the microprocessor will switch to the second cell 152. The cells 151-153 also may be switched manually through the software. If the operator clicks on the button “switch the cell”, the program automatically will go to the next cell, and the process starts. For the second cell 152 everything is the same, except, that instead of valve 151 and 171, it will be 152 and 173, and for cell three it will be 153 and 175.

[0072] In one embodiment, referring to FIG. 7, one embodiment of a system 700 incorporating features of the present invention could include two systems 710, 720, similar to the system 10 shown in FIG. 1. A water treatment system 730 is located between the two systems 710, 720. Referring to FIG. 7, each system 710, 720, generally includes a potentiometric module 12, a sample preparation module 14 and a voltammetric analysis cell 16 as shown and described with reference to FIGS. 1-3. Each system 710, 720 can be adapted or “programmed” to forward certain information or measurements to an external controller or system that is controlling the treatment process. For example, in a large water treatment plant there is typically one main controller that monitors and controls the whole plant. A series of small controllers could be in charge of certain subprocesses. In a large treatment plant with multiple waste streams, and treatment processes, the present invention could be expanded to provide a network of individual sensors (complete systems). Each “individual” system can be adapted to “talk” or communicate with a controller in the network identified as the master controller. The master controller can communicate with the plant process control system that will then manipulate the treatment process based on inputs from the system of sensors integrated throughout the treatment process.

[0073] These two systems 710, 720, one upstream from the treatment process center 730 and the other downstream of the treatment process, communicate with the treatment process controller to effect the efficiency of the treatment process and to ensure that overall discharge limits are not exceeded. This system will usually be interconnected with multiple other systems in a treatment plant. This system of systems then will contribute to the overall control of the treatment processes throughout the plant. The system 700 is generally adapted to detect contaminants and water characteristics in a water treatment process stream, both before (740) and after (750) the treatment procedure, and the correlation of these water characteristics measurements with a set of predetermined response tables that will affect the electrical and mechanical manipulation of treatment functions in the plant 730. Possible responses to data correlation could include valves to redirect water that is over discharge limits for specific contaminants, activation of alarms, direct input to treatment control process for removal of contaminants, automatic logging of all data collected, etc. The present invention provides a fully capable system to monitor and manage the water treatment process variables and to be able to respond automatically with predetermined actions to control the functions within the process. Additionally, the invention shall allow an operator to monitor the operation of a multi sensor system and dynamically reconfigure response levels and actions for each sensor and data output recipient module.

[0074] This invention is viable in either a standalone configuration or integrated into a system of systems. In this integrated mode as shown in FIG. 7, the present invention can comprise of a system 700 of at least two Stripping Voltammetric measurement devices for the detection of trace contaminants, with up to five potentiometric ion selective electrodes associated with each device to measure other sample characteristics. Each device shall consist of a structure for acquiring the sample for analysis of trace contaminants, a structure for real time measurement up to five other water characteristics in the sample, a structure for rapidly measuring contaminants in the sample, a structure for archiving data from the measurements, and a method for transmitting the data to a central control station. Each device shall be able to detect multiple elements and species down to at least 5 parts per trillion.

[0075] Each pair of devices working in conjunction upstream (740) and downstream (750) of a treatment process will communicate with the treatment process controls to affect the treatment additives and to optimize their efficiency. In addition to working with the treatment process controls, each device shall communicate with the central controller to archive measurement data.

[0076] The present invention, in an integrated mode shown in FIG. 7, provides near real time water management system, measuring water quality parameters to include but not limited to pH, temperature, oxidation reduction potential, alkalinity, and contaminant of concern concentration. Primary advantages of the present invention are those of reduced analysis time, reduced costs, lower detection limits, higher selectivity, increased sensitivity, minimal sample preparation, inclusive data management, flexible process control, and on-line measurement capabilities over current methods.

[0077] In one embodiment, referring to FIGS. 2 and 10, the cell 116 is adapted to direct a supporting electrolyte flow through the cell while immersing the electrode system 110, in the supporting electrolyte. As shown in FIG. 2, the cell 116 can include flow injector means from the hydraulics directing electrolyte from the sample preparation cell for injecting a flow of sample electrolyte through the cell 116 and onto the working electrode 142 when supported in the voltammetric measurement flow through cell 116.

[0078] The flow of electrolytes through the cell 116 is adapted to maximize the exposure of electrolyte to the electrodes while minimizing flow turbulence.

[0079] In one embodiment, referring to FIG. 10, the sample fluid 802 is filtered through filter 803 and pumped via pump 804 into a potentiometric measurement cell 805. The potentiometric measurement cell 805 includes up to five Commercial Off The Shelf (COTS) ion selective electrodes 806-810, or other COTS sensors. In this embodiment, sample preparation is not necessary. The controller 836 controls the COTS sensors 806-810.

[0080] The present invention may also include software and computer programs incorporating the process steps and instructions described above. FIG. 8 is a block diagram of one embodiment of a typical apparatus incorporating features of the present invention that may be used to practice the present invention. As shown, a computer system 50 may be linked to the system 10 of FIG. 1, such that the computer 50 and system 10 are capable of sending information to each other and receiving information from each other. In one embodiment, the computer system 50 could include a server computer adapted to communicate with a network 54, such as for example, the Internet. Computer system 50 and system 10 can be linked together in any conventional manner including a modem, hard wire connection, or fiber optic link. Generally, information can be made available to both computer system 50 and system 10 using a communication protocol typically sent over a communication channel or through a dial-up connection on ISDN line. Computer 50 and system 10 are generally adapted to utilize program storage devices embodying machine readable program source code which is adapted to cause the computer 50 and system 10 to perform the method steps of the present invention. The program storage devices incorporating features of the present invention may be devised, made and used as a component of a machine utilizing optics, magnetic properties and/or electronics to perform the procedures and methods of the present invention. In alternate embodiments, the program storage devices may include magnetic media such as a diskette or computer hard drive, which is readable and executable by a computer. In other alternate embodiments, the program storage devices could include optical disks, read-only-memory (“ROM”) floppy disks and semiconductor materials and chips.

[0081] Computer system 50 and system 10 may also include a microprocessor for executing stored programs. Computer 50 may include a data storage device 56 on its program storage device for the storage of information and data. The computer program or software incorporating the processes and method steps incorporating features of the present invention may be stored in one or more computers 50 on an otherwise conventional program storage device. In one embodiment, computer 50 may include a user interface 57, and a display interface 58 from which features of the present invention can be accessed. The user interface 57 and the display interface 58 can be adapted to allow the input of queries and commands to the system, as well as present the results of the commands and queries.

[0082] The system is adapted to be a manually operated device or fully automated system that very rapidly, and continuously, conducts a variety of analyses on electroactive elements in aqueous solutions. The system is designed to operate in a stand alone mode or integrated into a treatment system as an on-line continuous monitoring device. When integrated into a treatment system, this device (along with multiple others integrated into the same system) monitors and controls many control variables while maintaining alarm conditions and affecting immediate control on hydraulic valves and treatment systems. Organic and inorganic elements, ions and compounds can be detected and measured by voltammetric and/or potentiometric method. The concentration range of the measurements will be from 5 parts per trillion (ppt) to grams per liter (parts per thousand), and will range from instantaneous measurement times to less than 5 to 10 minutes.

[0083] The present invention generally provides an improved system for automatically sensing water characteristics, using Stripping Voltammetry and Potentiometric Analysis, in connection with the detection, managing, and processing of fluid material.

[0084] The system is adapted to detect electrochemically active components in process streams by sensing using Stripping Voltammetry and Potentiometric Analysis. The ASV technique has a detection limit of 5 parts per trillion for trace contaminants. In an automated or computerized system, data related to the measurement and analysis can be communicated to a central controller, archived and analyzed in accordance with a predefined lookup table. In a treatment system the data can be fed to affect the application of treatment materials to the water treatment mechanism. The same stream can be again sensed after the treatment process using Stripping Voltammetry and Potentiometric Analysis, communicated to a central controller, achieved and analyzed that data in accordance with a predefined lookup table. Data can be fed backward to affect the application of treatment materials to the water treatment mechanism, and affect a series of electrical and mechanical actions in the treatment process if analysis results are out of predefined limits. Therefore, the present invention can be a system of systems and apply state of the art feed forward and feed back algorithms required for control of modern treatment systems.

[0085] It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Claims

1. A system for measuring the presence and concentration of electro-active species in a liquid solution comprising:

a preparation module adapted to prepare and isolate the contaminants of concern in a liquid sample into its electro-active form;

a potentiometric module coupled to the preparation module adapted to gather environmental metrics of the liquid sample; and

a voltammetric module adapted to receive the sample from the potentiometric module or preparation module and identify and determine a concentration of electro-active species.

2. The system of claim 1 wherein the preparation module comprises a first section and a second section separated by a semi-permeable membrane, the first section and the second section each including an electrode for preparing the liquid sample when a voltage is applied to the electrodes for electrochemial oxidation of the liquid sample.

3. The system of claim 2 wherein a first part of the preparation module mixes the sample with a reagent and electrically stimulates the sample and a second part of the preparation cell receives waste from the voltammetric module.

4. The system of claim 3 wherein the first part of the preparation module is adapted to transfer only a part of the sample containing electro-active ions into the voltammetric module.

5. The system of claim 2, wherein a second part of the preparation module draws waste material from the first part through the semi-permeable membrane in the cell.

6. The system of claim 2 wherein the semi-permiable membrane facilitates electromechanical oxidation of the liquid sample and provides a closed circuit for electrical current to flow through the first section and the second section without physical mixing of a solution in each section.

7. The system of claim 2 wherein the preparation module is adapted to receive raw sample from the potentiometric module.

8. The system of claim 1 wherein the potentiometric module includes ports for coupling sensors and wherein data measured by the sensors is adapted to be correlated with data from voltammetric measurements in the voltammetric module.

9. The system of claim 1 wherein sample water is drawn through the potentiometric module and sent to the voltammetric module.

10. The system of claim 1 wherein the voltammetric module includes at least one flow through cell adapted to direct a flow over an electrode in the module.

11. The system of claim 1 wherein the voltammetric module is adapted to process the sample in a stripping voltammetry process.

12. The system of claim 1 wherein the voltammetric module comprises at least one flow through cell containing three electrodes including, a working electrode, a reference electrode and an auxiliary electrode.

13. The system of claim 11 wherein the flow through cell further includes an inlet for providing a standard solution sample to the measurement cell required for analysis calibration and a plating solution required for electrode modification.

14. The system of claim 1 further comprising at least two electrodes in the sample preparation cell, at least one electrode in the potentiometric module, and at lest three electrode in each flow through cell in the voltammetric module.

15. The system of claim 14 wherein the electrodes are composed of graphite, impregnated with organic and inorganic compounds, which is hermetically pressed into a polymer body, and hermetically pressed into the respective cell.

16. The system of claim 15 wherein the working electrode is an impregnated graphite, gold, platinum, glassy carbon or iridium.

17. The system of claim 15 wherein the reference electrode is a silver electrode hermetically pressed into a polymer body and hermetically pressed into the flow through cell.

18. A method for detecting and identifying contaminants in liquids comprising the steps of:

measuring environmental properties of a liquid sample taken from a liquid source preparing the sample into its electro-active form; and

identifying and determining a concentration of contaminants in the sample by a stripping voltammetric process.

19. The method of claim 18 wherein the step of preparing the sample further comprises the step of adding a predetermined reagent to the sample to prepare the sample for measurement.

20. The method of claim 19 wherein the reagent is an acid, base, salt, organic agent or inorganic agent.

21. The method of claim 18 wherein the step of measuring environmental properties of the sample further comprises the step of using at least one ion selective electrode to perform analysis on the sample.

22. The method of claim 18 wherein the step of identifying further comprises the step of using three electrodes of a flow through cell, a working electrode, an auxiliary electrode, and a reference electrode, capable of detecting concentration of electro-active ions to a lower limit of about 5 parts per trillion.

23. The method of claim 18 wherein the voltammetry process occurs within about 5 minutes of inputting the sample liquid into the voltammetric module.

24. The method of claim 18 further comprising the steps, prior to the stripping voltammetry process of:

providing a standard solution to a measurement cell required for analysis calibration; and

providing a plating solution to the measurement cell for electrode modification.

25. A water treatment system comprising:

a first system for measuring the presence and concentration of electro-active species in liquid solution in an upstream location from a water treatment process; and

a second system for measuring the presence and concentration of electro-active species in a liquid solution in a downstream location from the water treatment process, the first and second system adapted to communicate sample characteristics to an independent treatment system adapted to control the treatment and processing of the contaminated water.

26. The water treatment system of claim 25, wherein the first system and the second system each comprise:

a preparation module adapted to convert a liquid sample into its electro-active form;

a potentiometric module coupled to the preparation module adapted to gather environmental metrics of the liquid sample; and

a voltammetric module adapted to receive the sample from the potentiometric module or preparation module and identify and determine a concentration of electro-active species.

27. The water treatment system of claim 26 further comprising:

an automated hydraulic device for automatically drawings and conveying liquid samples and solutions through the system; and

a microprocessor based controller for the automated management of all operational aspects of the system, with the ability to network multiple individual sensor systems into a system of systems capable of data sharing and archiving data.