Abstract: A test method and apparatus for determining the content of carboxylic acid-based corrosion inhibitors in a coolant or heat exchange fluid. The amount of acidic reagent added to the coolant or fluid between two pH equilibrium points is measured to determine the amount of inhibitors. The refractive index can be measured to determine the amount of freezing point depressant.

Abstract: A test method and apparatus for determining the content of carboxylic acid-based corrosion inhibitors in a coolant or heat exchange fluid. The amount of acidic reagent added to the coolant or fluid between two pH equilibrium points is measured to determine the amount of inhibitors. The refractive index can be measured to determine the amount of freezing point depressant.

Abstract: In a process for titrating substances by adding increments of a titrant in time intervals, the course of the reaction is monitored in its approach toward the end point (EP), and the addition of titrant is controlled. At least one differential component is determined from the course of the reaction and used for controlling the addition of titrant. The process can be performed by an apparatus that includes a delivery unit for the titrant and suitable devices for performing the monitoring, differentiating and control functions.

Abstract: An apparatus for generating high purity acid or base in an aqueous stream for use in analysis. For generating a base, the aqueous stream is directed through a cation exchange bed having first strongly acidic and second weakly acidic portions. An electrical potential is applied to the bed. Cations on the bed electromigrate into the aqueous stream while hydroxide ions are electrolytically generated to form a base-containing eluent. Analytes to be detected and the generated eluent flow through a detector.

Abstract: The invention relates to apparatus and a method for measuring NOx in biochemical processes, and to apparatus and methods for real time measuring the nitrification and/or denitrification rate of a liquid with or without suspended solids.

Abstract: The present invention relates to apparatus and a method for measuring ammonia in biochemical processes, and more particularly to apparatus for real time measuring the amount of ammonia in a liquid with or without suspended solids.

Abstract: The invention relates to an analysis device with a multi-way valve which is connected, via a pump line, to a bidirectional pump. A storage member for storing a sample fed to it and any auxiliary substances is accommodated in the pump line. The multi-way valve is connected, via two separate discharge lines, to an analysis vessel. The multi-way valve and the pump are controlled, with the aid of a microprocessor, in such a manner that the following steps are carried out:a. connecting a first feed line to the pump line via the multi-way valve, in order to feed sample to the storage member,b. using the pump to suck the sample into the storage member,c. connecting the pump line, via the multi-way valve, to a first discharge line which opens into the analysis vessel,d. feeding some of the sample present in the storage member to the analysis vessel via the pump and via the first discharge line,e. connecting the pump line to the flushing line via the multi-way valve,f.

Abstract: A method for determining the concentration of acid-gases in an amine-regeneration system, such as is typically found in a natural gas refining plant, having a device for measuring the pH of the system from which the concentration of the acid-gases complexed and the amine can be calculated using an empirically-derived relationship between acid-gas concentration and pH. The invention also includes a system for controlling amine regeneration based upon the above described determining method.

Abstract: A neutralization testing apparatus and a neutralization testing method which allow a neutralization reaction rate of a liquid sample such as lubricant oil to be accurately measured are provided. Reagent injecting device for injecting a reagent which neutralizes the liquid sample is provided on a lid member of a closed container into which the liquid sample is charged. The reagent injecting device is an acid injecting port which penetrates through the closed container and an air-tight sealing member which closes the acid injecting port and which permits an injector needle for injecting the reagent to penetrate therethrough. Because no gas leakage occurs even when the injector needle is penetrated because of the elasticity of the air-tight sealing member, the measuring conditions within the closed container do not change and the neutralization reaction rate may be found accurately.

Abstract: The present invention provides an automated analyzing apparatus which comprises: a syringe unit for inhaling or transfering liquid such as sample, reagents and washing solution by moving the piston (12) by a certain distance; a built-in stirring bar (31) located within the syringe barrel (11); a driving unit for rotating the stirring bar (31); a driving means (13) for moving the piston (12) up and down; several connection paths (15a-15f) located in the lower part of the syringe barrel (11) or in the piston (12) where the sample, the reagents, the washing solution, and air can be provided or discharged; 2-way on/off valves (16a-16f) connected to each connection path (15a-15f); detecting means (3) positioned in the outer wall of the syringe barrel (11) perpendicular to the piston shaft (14); additional heating and cooling unit (4) for temperature control or sample digestion; control unit (6) for controlling the driving means (13), the detector (2) and valves (16a-16f) described above.

Abstract: The total base number of an oil sample of measured volume is determined by solvating the oil sample, adding a predetermined amount of acidic species to the solvated sample to react the acidic species with any basic species contained in the oil sample, extracting the remaining acidic species into an extractant phase, separating the extractant phase from the oil sample, and measuring the acidic species content of the extractant phase to determine the quantity of basic species in the oil sample. The same technique may be used to determine the total acid number of an oil sample by adding a predetermined amount of basic species to the sample and measuring the basic species content of the extractant phase.

Abstract: An apparatus is proposed making it possible in automated manner to perform several analyses on the same sample. For this purpose several fixed, chemical preparation cells (10) can separately receive several fractions of the same sample. Reagent injection systems (24) associated with these cells, as well as stirrers (14) make it possible to prepare, in each of them, a chemical preparation which is transferred into an analysis cell (36) associated therewith by an air ejector (44). The same ejector discharges the preparation to the drain (38) when the analysis has been completed. Ducts (70, 72), as well as a discharge line (62) then make it possible to wash, rinse and empty each chemical preparation cell (10).

Abstract: A process and test kit for the rapid qualitative determination of fat oxidation based on an iodometric method for peroxide value and employing ready-made test solutions is disclosed. A visible color change is used to determine whether a fat sample contains an amount of fat peroxides in excess of a predetermined amount, and is therefore unacceptable.

Abstract: A system for dosing liquids includes a dosing device, a device for operating the dosing device, a device for entering data and a unit for calculating the dosing displacement. Data are allocated to a dosing device according to the invention which are characteristic for the inside diameter of the dosing device and thus enable precise dosing. In addition the invention concerns a method for dosing using the system according to the invention.

Abstract: The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions.

Abstract: Both a method and a kit for testing the fitness of a polyolester lubricant of the type used in a refrigerant compressor are provided. In the method of the invention, a solution for indicating an excess acidity of the polyolester lubricant is obtained by mixing a color acidity indicator, such as alizarin, with a sufficient amount of an alkaline to neutralize the inherent acidity of the lubricant. The resulting solution changes color only upon the presence of an excess acid condition associated with a compressor malfunction, such as burn out. Both the method and the kit are particularly well adapted to determine the fitness of polyolester lubricants of the type prepared by the reaction of trimethylolpropane with a mixture of a branched and a linear acid.

Abstract: A process and test kit for the rapid qualitative determination of fat oxidation based on an iodometric method for peroxide value and employing ready-made test solutions is disclosed. A visible color change is used to determine whether a fat sample contains an amount of fat peroxides in excess of a predetermined amount, and is therefore unacceptable.

Abstract: The invention relates to colorimetric titration method, a titrator and colorimeter device. The titrating apparatus comprises radiant energy means for producing radiant energy. The device includes means for modulating an amplitude of an intensity of the radiant energy at a modulation frequency. The radiant energy is partially absorbed by an adjacent solution within a sample beaker having a color indicator dissolved therein. Radiant energy focusing means focuses the modulated radiant energy transmitted through the sample and beaker on radiant energy detection means. The radiant energy detection means produces a transmitted signal wherein an intensity of the transmitted signal is directly proportional to the intensity of transmitted energy. Filtering means filters the transmitted signal, such that a center frequency of the filtering means matches the modulation frequency of the radiant energy means.

Abstract: The total alkalinity of an aqueous metalworking fluid is monitored and controlled by a continuous titration method that continuously supplies a stream of the metalworking fluid, at a known, controllable flow rate, to a flow through chamber having therein a static mixing element. Simultaneously and separately a stream of acid titrant, of known acid concentration is injected into the flow through chamber at a known controllable flow rate. The acid titrant and metalworking fluid mix and react in the chamber and the reacted metalworking fluid exiting the chamber passed over the tip of a pH electrode. The pH of the reacted metalworking fluid is continuously monitored and the output of the pH electrode used to adjust the flow of acid titrant to the chamber until an endpoint pH valve (typically a pH of 4) is reached.

Abstract: An automated analysis system is provided for the determination of impurities in a liquified hydrocarbon stream. The system employs a hydrocarbon capture vessel for capturing a hydrocarbon sample, a water scrubbing vessel for extracting impurities from the hydrocarbon sample and a titration zone for analyzing the amount of impurities in the aqueous extract.

Abstract: The total base number of an oil sample of measured volume is determined by solvating the oil sample, adding a predetermined amount of acidic species to the solvated sample to react the acidic species with any basic species contained in the oil sample, extracting the remaining acidic species into an extractant phase, separating the extractant phase from the oil sample, and measuring the acidic species content of the extractant phase to determine the quantity of basic species in the oil sample. The same technique may be used to determine the total acid number of an oil sample by adding a predetermined amount of basic species to the sample and measuring the basic species content of the extractant phase.

Abstract: Automation of the coulometric Karl Fischer titration has allowed for the accurate, precise determination of moisture content of lyophilized hGH formulations. The system of the present invention utilizes a vented, two-hole sampling/dispensing probe that dispenses titrant and withdraws sample solution through the closed container rubber septum into the Karl Fischer titration reaction vessel. This approach eliminates erroneous results due to environmental moisture contamination or loss of material during the sample transfer process. The system of the present invention is also equipped with a fixed loop valving system, which facilitates the precise measurement of a defined amount of water as a standard. This allows for an accurate accessment of system suitability that was lacking with commercial water standards due to inaccurate moisture content presumably from moisture contamination of the standard under storage and/or at the time of manufacture.

Abstract: The disclosure describes an apparatus for performing at least two successive chemical reactions in the same container. In order to successively carry out several chemical reactions in the same container (10), e.g. dosing uranium in the presence of plutonium and fission products, the container is placed in a working station above which issue tubes (16, 20) for supplying the products necessary for the reactions. When a product has to be introduced, a computer controls the descent of the corresponding tube. When the product may react inopportunely if it drops into the container (10) outside the time intended for this purpose, the lower end of the product supply tube (16) is automatically laterally displaced with respect to the container, when the tube is in the top position, e.g. by the cooperation of a pawl (102) with a slot (100) forming a cam.

Abstract: A method and apparatus for automatically measuring the acidity of overhead water in an oil refinery, and dispensing a neutralizing agent into the refinery system at a rate responsive to that measurement. A sample of overhead water is collected and passed through a filter and cation exchange resin. The acid concentration of the sample is then automatically measured and a signal generated based on the concentration. The signal goes to a controller which controls the dispensation rate of neutralizing agent into the refinery system, thus reducing the acidity of the overhead water and limiting the corrosive effects of such acidity.

Abstract: A method and apparatus for measuring the amount of residual chlorine in solution with enhanced accuracy. The basic measurement technique involves introducing a solution of iodide ion into the sample to reduce the chlorine, thereby producing a proportionate amount of iodine; measurement of the iodine concentration is used to infer the initial amount of chlorine. The accuracy of this measurement technique is enhanced by introducing a sufficient amount of scavenger, preferably finely divided zinc metal, into the iodide solution to react with trace amounts iodine present therein.

Abstract: A titration apparatus, which operated volumetrically and/or coulometrically, includes a basic apparatus with a control and actuation arrangement for the volumetric metering of reagents, a metering unit for the volumetric titration removably attached to the basic apparatus, and mechanical coupling elements for connecting the metering unit to the actuation device. Instead of the volumetric unit or in addition thereto, a coulometric titration cell may be connected with the basic apparatus directly or by an adapter unit, while using the same control device as the metering unit.

Abstract: An analyzer system for improving quality of a reaction product, wherein a liquid sample must be maintained at an elevated temperature to prevent precipitation of titratable species, comprises a heated sample and dilution section, an autotitrator and a programmable controller. In operation a liquid sample to be analyzed is withdrawn from a reactor and maintained at reactor temperature while being diluted. The diluted sample is then cooled and passed to an autotitrator for analysis. The analyzer system includes a programmable controller for automatic unattended dilution of successive samples.

Abstract: A method of determining populations of live, whole bacteria electrochemically. The bacteria are filtered, and the filtrate is employed in association with an electrochemical measuring unit to determine the bacteria density. In accordance with a flow-through method, the average signal over the predetermined time period of the test is employed, in conjunction with a constant, to determine the population. In accordance with the bypass method, reagent is passed through a bypass line to the electrochemical measuring unit, and the resulting signal is subtracted from the signal resulting from the filtrate, a constant being employed to correlate the resulting remainder with bacteria count. A changing-concentration method employs a changing concentration of bacteria in the same fluid to determine populations of bacteria. A saved-sample method employs a second test of the same filtrate, after a predetermined time period, to compensate for any contaminants that may be present.

Abstract: An improved technique and apparatus for automatic titration for determining the water content of a sample by a Karl Fischer (K.F.) reaction. Rather than requiring titration from one endpoint to another identical endpoint, each determination is made using a calibration relative to the water equivalent of a known amount of titrant together with the change in sensor output that occurs when a sample is added to the K.F. reagent. Improved accuracy and speed of analysis results.

Abstract: An analyzer system for improving quality of a reaction product, wherein a liquid sample must be maintained at an elevated temperature to prevent precipitation of titratable species, comprises a heated sample and dilution section, an autotitrator and a programmable controller. In operation a liquid sample to be analyzed is withdrawn from a reactor and maintained at reactor temperature while being diluted. The diluted sample is then cooled and passed to an autotitrator for analysis. The analyzer system includes a programmable controller for automatic unattended dilution of successive samples.

Abstract: A chemical test kit and method for detecting the presence of impurities in an oil sample is provided. The test kit is comprised of two flexible translucent or transparent containers, each with at least one breakable capsule mounted within it. One of the flexible containers has a means for separating an aqueous layer from an oil layer. The capsules contain reagents capable of extracting the impurity to be detected from the oil into an aqueous layer and indicating the presence of a threshold concentration of the impurity. The method involves the steps of introducing an oil sample into a first flexible container, breaking the capsule within it by squeezing the flexible container in the vicinity of the capsule, transferring the aqueous layer to the second container, and breaking the capsule within the second container in the same manner. A chemical reaction occurs in the second container indicating whether the impurity is present at a given threshold concentration.

Abstract: An automatic titration device for use in either batch processing or a continuous processing mode to identify quantitative fluid properties. The device consists of a plurality of reservoirs each connected to a respective plurality of pumps. A central computer controls individual pump speeds and therefore the pump output mix through a delivery tube that delivers fluid mixture through an ultrasonic mixer to a mixing tube whereupon a color detector is disposed to detect indicator color changes of the liquid for providing indication back to the central computer for calculation of fluid presence, fluid equivalent points, and related fluid properties.

Abstract: An automatic analytical apparatus in which a series of operations ranging from the sampling into a treating receptacle, pretreatment, analysis and discharge of a fluid sample to the preparation for the next analysis are repeated automatically in order, wherein the time-dependent variation of the composition is traced successively. This permits the presence of the composition variation or the course of the composition variation to be confirmed or the composition variation to be controlled, automatically.

Abstract: A titrating system includes a pulse length modulator for controlling a drive train including a DC drive motor to supply a given dosage of a titrating agent to a specimen. The pulse length modulator is so designed that the drive motor is supplied with DC-current pulses having a constant amplitude, the lengths of the pulses being a function of the start-up characteristic of the drive apparatus. In order to produce the simultaneous dosing of two different titration agents, at least two dosing arrangements and at least two drive trains are provided, thereby affording a joint control-train pair for the alternate selection of the drives. By virtue of the combination of several control-train pairs, a large number of simultaneously selectable pairs of supply devices can be provided. In a preferred embodiment, the pulse length modulator supplies to the electromechanical drive apparatus DC voltage pulses having a generally constant amplitude.

Abstract: Efficient control of the pH of a flowing alkaline wastewater stream is accomplished by monitoring the pH of the flowing stream, generating a signal in response to the pH monitored, and injecting CO.sub.2 as necessary to reduce the pH. High pressure liquid CO.sub.2 is supplied to a proportional control valve which is operated in response to the signal to change the high pressure CO.sub.2 fluid to an intermediate pressure CO.sub.2 fluid in a manner so as to significantly reduce its density by creating a significant gaseous fraction. This lower density CO.sub.2 fluid is supplied to a spring-loaded injector having an orifice in communication with the flowing stream. The intermediate pressure is above the pressure at which the injector opens whereby the lower density CO.sub.2 fluid is injected into the flowing stream, allowing particularly precise control to be achieved.

Abstract: A process and apparatus for automatically monitoring or adjusting, or both, the concentration of total reducers (i.e. reduced sulfur-containing constituents which consume iodine) in an aqueous medium (e.g. waste water stream) whereby the time period for iodine titration of an untreated sample of the aqueous medium is automatically measured by measuring a time of light being transmitted through a titration sample cell and this time measurement is automatically translated into an output signal to either a monitoring means or a process adjustment means (e.g. oxidant chemical feed pump) or both.

Abstract: A flow injection analysis flow cell suitable for precipitation titration flow injection analysis wherein the flow cell has a chamber and a dammed space within the chamber. The carrier containing the precipitate is flowed into the dammed space and overflows it into the chamber. The flow cell is designed so that a chemical sensing probe can be inserted into the dammed space to allow precipitation titration flow injection analysis with reduced problems of flow cell plugging.

Abstract: A gravimetric method for determining the iodine adsorption number of carbon black is disclosed. The concentration of an accurately weighed iodine solution is determined by titrating with a standardized titrant and determining the concentration of the iodine solution by the weight of the standardized titrant needed to reach the titration endpoint. An appropriate amount of accurately weighed iodine solution is mixed with an accurately weighed amount of carbon black, and the mixture is equilibrated. The concentration of the resulting supernatant is determined by determining the weight of the standardized titrant needed to reach the titration endpoint. The iodine adsorption number is then determined based on the gravimetrically determined concentrations of the solutions. Preferably, the method is semi-or fully automated, and an apparatus for accomplishing the same is disclosed.

Abstract: A method for titration flow injection analysis by introducing a multicomponent sample into a carrier stream which flows into a mixing/sensing cell and titrating with a reactant more than one component of the sample by sensing a plurality of endpoints. The apparatus of the invention includes a stirring means within the mixing/sensing cell which generates helical flow within the cell so that bubbles are not retained in the cell.

Abstract: There is disclosed herein an automated sample preparation system for chemical assay of samples of materials. The sample preparation system includes a sample preparation chamber which includes a removable cup for taking to the location of solid or very viscous samples. The cup may be attached in sealing relationship to a cap through which extends various utilities such as a mixer/grinder to grind solid samples and mix non-homogeneous samples, a fill pipe to pump in liquid samples, an effluent pipe in the sump of the cup to allow pump of samples and solvents and a nozzle to allow liquids to be sprayed against the walls. A sample metering valve associated with the sample preparation chamber allows a known volume of sample to be isolated so that solvent may be pumped in to dilute the sample to a user defined concentration.

Abstract: Titration apparatus includes two cells that receive and contain liquids and are transparent to light. A liquid having an unknown characteristic and mixed with an indicator that is optically responsive to a titrant is disposed in the cells. Light is transmitted through each cell to separate photosensors. The photosensor signals are compared and a titrant is added to one of the cells in known-volume increments until the difference between the signals reaches or exceeds a prescribed threshold. The characteristic of the liquid is calculated from the quality of known concentration titrant added in order to reach or exceed the prescribed threshold.

Abstract: A coated-wire electrode for potentiometrically titrating surfactant molecules having more than ten carbon atoms includes an electrically-conductive core coated with a semipermeable membrane. The membrane matrix included a polymer, a plasticizer and an ion-exchange material consisting essentially of dimidium bromide or disulphine blue in suitable proportions to be surfactant selective. The membrane is responsive to anionic, cationic and amphoteric surfactants as well as alkoxylated nonionic surfactants.

Abstract: Apparatus and method for automatic microbatch reaction including a reactor having a reaction chamber, such as a 1.5 milliliter plastic centrifuge tube having a conical bottom. An automatically actuated injection valve is used to inject less than 1 milliliter of a sample into the reaction chamber. One or more automatically actuated reagent valves are used to introduce respective pressurized reagents into the reaction chamber to process the sample. The volume of the reagent(s) introduced into the reaction chamber is less than 1 milliliter and controlled by the on time of the respective reagent valve. The automatically actuated valves are controlled by a computer based timer. A sensor positioned in the chamber, such as a pH electrode, can be used to analyze the processed sample in place or the processed sample can be analyzed by flowing it from the reaction chamber through a flow-through detector, such as a flow-through spectrophotometer.

Abstract: A chemical test kit and method for detecting the presence of impurities in an oil sample is provided. The test kit is comprised of two flexible translucent or transparent containers, each with at least one breakable capsule mounted within it. One of the flexible containers has a means for separating an aqueous layer from an oil layer. The capsules contain reagents capable of extracting the impurity to be detected from the oil into an aqueous layer and indicating the presence of a threshold concentration of the impurity. The method involves the steps of introducing an oil sample into a first flexible container, breaking the capsule within it by squeezing the flexible container in the vicinity of the capsule, transferring the aqueous layer to the second container, and breaking the capsule within the second container in the same manner. A chemical reaction occurs in the second container indicating whether the impurity is present at a given threshold concentration.

Abstract: The sample and the reagent required for titration are fed into a titration vessel (1), the reagent and/or sample being supplied intermittently in the form of pulses of liquid. Toward this end, a controlled valve (9) is provided in the supply line (4) for the reagent. The opening and closing times of this valve (9) and, hence, the frequency and duration of the pulses of liquid, are chosen such that the ratio of the average sample flow to the average reagent flow is sufficient to achieve the ratio of sample to the reagent at the equivalence point. This renders continuous titration possible, for which only one pump (7) is needed, which does not require any complex servo system and, therefore, has a low energy consumption.

Abstract: A system and method for quantitative analysis of a solution to determine the concentration of a chemical species in the solution. The system includes a reaction vessel; a source of at least one liquid reagent for reacting with the chemical species being tested for; a conduit leading from the reagent source to the reaction vessel; pneumatic pressure for forcing the reagent through the conduit; controls for controlling the amount of reagent added to the reaction vessel; and a detection device for detecting reaction between the reagent and the chemical species.

Abstract: In a new method for the titrimetric determination of the contents in a chemical solution, wherein a quantity of a reaction component, corresponding in each case to the change of a certain physical-chemical magnitude or a value derived from that, is added to a reaction component and this added quantity is so regulated that it will be a function of the prior and/or predetermined magnitude change or changes and the already added total quantity of one of the reaction components. In the method mentioned, the minimum quantity added is not allowed to fall below a predetermined percentage, e.g., 1.0 percent, or even 0.5 to 0.1 percent, of the already added quantity. The apparatus for performing the method therefore contains devices operable to regulate the quantity to be added as a function of the magnitude change and the already added total quantity of one of the reaction components. Potentiometric titration is the most important area of application of the new determination method.

Abstract: A method and apparatus for automatically measuring the grain fineness, the gypsum content and the limestone content of a cement sample.A first fraction of the sample is loaded by a vibrating hopper into a crucible resting on an automatic scale. This crucible is handled sequentially by tongs on two revolving arms carried on slidable vertical shafts. The circular paths of the arms intersect at a point just above the scale. Motions of the arms and of the tongs are controlled by a programming unit. The weighed sample is poured into a sieve and the weight of oversize grains is automatically related to the sample weight.Gypsum is measured by heating a second fraction of the sample at 1000.degree. C. plus in an oxygen stream, Fe powder being added from a fixed hopper. The crucible is raised into an induction furnace. Released SO.sub.2 is bubbled in a titration cell to which potassium iodate is gradually added by a burette giving an automatic read-out of the SO.sub.3 (gypsum) titration.

Abstract: Disclosed are end point indicator compositions and devices containing them, particularly useful as air freshener devices, comprise compositions containing a polar indicator dye which assumes a first color or is colorless in the presence of a room temperature volatilizable solvent which is initially present in excess and a small amount of a proton donating compound. The indicator dye assumes a second color visually distinct from the first color in the presence of the proton donating compound after the majority of the solvent escapes from the remainder of the composition. Optionally, the compositions further include color change developers and/or secondary dyes to render the change to the second color, indicating attainment of the end point, more apparent to a user.

Abstract: A coated-wire electrode for potentiometrically titrating surfactant molecules having more than ten carbon atoms includes an electrically-conductive core coated with a semipermeable membrane. The membrane matrix includes a polymer a plasticizer and an ion-exchanger material consisting essentially of dimidium bromide-disulphine blue in suitable proportions to be surfactant selective. The membrane is responsive to anionic, cationic and amphoteric surfactants as well as alkoxylated nonionic surfactants.