Abstract: A breath simulator for supplying a breath test analyzer with a sample effluent of ethyl alcohol that controls headspace and adjacent effluent passageway temperature.

Abstract: This invention relates to a system for testing the operation of a detection instrument, which comprises a first enclosure having at least two ports and containing a fluid comprising a substance detectable in gas form by the instrument, said fluid being present in part as a vapor phase and in part as a liquid phase in equilibrium with one another, said first enclosure being interconnected with the instrument such that the fluid contained in the first enclosure can be dispensed to the instrument via at least one port of said first enclosure; a second enclosure having at least one port and containing either the same or a different fluid in gas form as compared with the first enclosure, said second enclosure being adapted for selective dispensing of a known or ascertainable mass of the fluid contained therein via at least one port thereof, and being interconnected with the first enclosure such that said mass can be introduced into the volume within said first enclosure through at least one port thereof, thereby t

Abstract: A continuous emissions monitoring system is in fluid communication with a flue stack conducting exhaust gas from a combustion source. The continuous emissions monitor system comprises an analyzer for measuring concentrations of an analyte present in the exhaust gas. A probe is in fluid communication with the flue stack to acquire a sample of exhaust gas from the flue stack. The probe is also in fluid communication with and located upstream of the analyzer. The probe tends to remove analyte from the sample. A calibration checking system is in fluid communication with the probe. The calibration checking system includes a source that provides a flow of a known concentration of calibration material to be measured by the analyzer. The calibration material is the same as the analyte. A humidifier is associated with the source to provide moisture to a flow of calibration material.

Abstract: A calibration assembly generates elemental mercury and oxidized mercury for calibrating components of a mercury monitoring system, including making necessary adjustments to efficiencies of a mercury compound converter and an elemental mercury detector. The calibrator generates an elemental mercury sample having a known elemental mercury concentration, [Hg0]1 and combines an oxidizing component with the elemental mercury sample, thereby producing a reduced concentration of elemental mercury [Hg0]2 within the sample. The calibrator measures the concentration of elemental mercury [Hg0]2 within the sample and calculates a difference between the known elemental mercury concentration, [Hg0]1 and the reduced concentration [Hg0]2. The difference between [Hg0]1 and [Hg0]2 is substantially equal to the concentration of oxidized mercury produced by the calibrator.

Abstract: A continuous emissions monitoring system is in fluid communication with a flue stack conducting exhaust gas from a combustion source. The continuous emissions monitor system comprises an analyzer for measuring concentrations of an analyte present in the exhaust gas. A probe is in fluid communication with the flue stack to acquire a sample of exhaust gas from the flue stack. The probe is also in fluid communication with and located upstream of the analyzer. The probe tends to remove analyte from the sample. A calibration checking system is in fluid communication with the probe. The calibration checking system includes a source that provides a flow of a known concentration of calibration material to be measured by the analyzer. The calibration material is the same as the analyte. A humidifier is associated with the source to provide moisture to a flow of calibration material.

Abstract: A method and apparatus for calibrating a sensor used to sense the concentration of vaporized hydrogen peroxide (VHP). A concentration of liquid hydrogen peroxide in an aqueous solution is determined and correlated with a corresponding concentration of vaporized hydrogen peroxide indicative of an “actual” vaporized hydrogen peroxide concentration. An error value is determined by comparing the “actual” vaporized hydrogen peroxide concentration to a “measured” vaporized hydrogen peroxide concentration, indicated by the sensor being calibrated. The error value is used to properly calibrate the sensor.

Abstract: A breath simulator for supplying a breath test analyzer with a sample effluent of ethyl alcohol that controls headspace and adjacent effluent passageway temperature.

Abstract: Embodiments of the present invention relate to a gas sensor system comprising a gas sensor, a fluid reservoir enclosing a fluid and in proximity to the gas sensor and a membrane positioned between the gas sensor and fluid reservoir, wherein the membrane allows a sufficient amount of a test gas generated from the fluid to contact the gas sensor for testing. Embodiments also relate to a method of testing a gas sensor, the method comprises contacting reagents within a fluid reservoir, generating a test gas and contacting a gas sensor with the test gas sufficient to test the gas sensor.

Abstract: A system automatically maintains at least one of a pH level and a sanitizing agent level of water in a water feature. The system includes a sensor assembly responsive to at least one of a pH level of the water and a sanitizing agent level of the water. The system further includes a controller which generates control signals in response to signals from the sensor assembly. The system further includes at least one of a first source containing an sanitizing agent material and a second source containing a pH-modifying material. The system further includes a third source comprising a valve assembly and a third container containing a liquid calibrant material. The valve assembly is responsive to at least a portion of the control signals from the controller by selectively allowing the calibrant material to flow from the third container through the sensor assembly to the water feature.

Abstract: Provided is a novel system and apparatus for producing primary standard gas mixtures. The system includes providing a gas permeation device having a constant diffusion rate into a temperature controlled enclosure; connecting a supply source of a component to the permeation device; routing the component from the gas permeation device to a product container until a desired amount of said component in the product container is reached; and supplying a balance of purified gas to the product container to obtain a known concentration of component in the primary standard gas mixture.

Abstract: A method for determining the viscosity and relative change of viscosity of a fluid over plural shear rates caused by a decreasing or increasing pressure differential resulting from fluid flow to a defined chamber in a capillary system. The flow of liquid through the capillary restriction, the pressure variation rate and known dimensions of the system can be used typically by a processor to determine a rheological property of a fluid.

Abstract: Application of a reference mixture of natural products for systematic analysis and comparison of the properties of biphasic solvent systems in counter-current/partition chromatography. Because the reference mixture is comprised of compounds with varying polarities, functional groups, and structural features it provides a rational method for mapping the optimal resolution polarity range of a particular solvent system. The mapping of optimal resolution polarity ranges of solvent systems provided for the description of the overall optimal resolution polarity range of a solvent system family, comprised of the same solvents in different proportions. By comparing the reference mixture performance in the individual members of a solvent system family, the solvent system that best functions as the representative of, or portal to, the solvent system families is determined. Use of the reference mixture also afforded a method to compare the overall optimal resolution polarity ranges of solvent system families.

Abstract: A method and kit for calibrating a CO-concentration sensing electrode that employs a standard solution obtained by dissolving a predetermined amount of a CO-releasing boranocarbonate to provide a known concentration of CO.

Abstract: Methods for operating a sensor device are provided, which may include (a) providing at a site (e.g., implanting in a patient) a device which comprises at least first and second reservoirs, a first sensor and corresponding first reference sensor located within the first reservoir, a second sensor and corresponding second reference sensor located within the second reservoir, a first reservoir cap closing an opening in the first reservoir and a second reservoir cap closing an opening in the second reservoir, and a power source, control circuitry, and electrodes for selectively disintegrating each reservoir cap; (b) disintegrating the first reservoir cap and operating the first sensor and reference sensor; and (c) using the first reference sensor to determine whether the first sensor is operating properly. If not operating properly, then the control circuitry initiates disintegration of the second reservoir cap and operation of the second sensor and reference sensor.

Abstract: A system and method is provided for obtaining calibration curves for CO and CO2 during laboratory calibration of one or more remote emissions sensing (RES) instruments, and for self-calibration of on-road RES instruments to compensate for changes in background CO and CO2 column densities.

Abstract: A breath simulator for supplying a breath test analyzer with a sample effluent of ethyl alcohol that controls headspace and adjacent effluent passageway temperature.

Abstract: A breath simulator for supplying a breath test analyzer with a sample effluent of ethyl alcohol that controls headspace and adjacent effluent passageway temperature.

Abstract: A method of performing calibration and quality control of a sensor for determining a parameter in a test fluid in which method a calibration and quality control cycle is repeated. A cycle includes the steps of performing a calibration and a quality control of the sensor using independent reference materials. In the method a reference material is in one cycle used in the quality control step which in a previous cycle was used in the calibration step. The present invention further provides an apparatus for performing the method.

Abstract: A test system comprises a sensor container and a testing device. The sensor container has a base and a lid. The container encloses test sensors therein. The container includes a calibration label attached thereto. The label includes electrical contacts located thereon. The electrical contacts encode calibration information onto the calibration label. The testing device has an auto-calibration feature externally located thereon. The testing device is adapted to determine the analyte concentration in a fluid sample. The auto-calibration feature includes calibration elements that communicate with the electrical contacts on the calibration label. The testing device is adapted to determine the calibration information encoded on the calibration label in response to the calibration elements engaging the electrical contacts. The encoded calibration information is determined without inserting the sensor container or the calibration label into the testing device.

Abstract: In an industrial installation equipped with a sensor, a method is provided for checking the sensor and providing a measurement sequence associated with the sensor. Monitoring occurs for a thermodynamic parameter of a monitored fluid circulating in the industrial installation, by sensing the fluid using the sensor while the industrial installation is operating and by collecting and processing an electric signal emitted by the sensor using the measurement sequence. A perturbation is produced of fluid origin of the thermodynamic parameter while the installation is operating and the fluid circulates in the installation in order to act on a sensitive element of the sensor and cause a modification of the electric signal emitted by the sensor. The method performs collecting and analyzing of the modified signal from the sensor using the measurement sequence.

Abstract: A system and method are described herein for self-referencing a sensor that is used to detect a biomolecular binding event and/or kinetics which occur in a sample solution flowing along side a reference solution in a micron-sized deep flow channel.

Abstract: An apparatus for providing a test gas to a gas monitoring instrument having a window for admitting gas to a gas sensor therein, is formed from a mechanical adaptor open at a portion thereof and having walls constructed and arranged such that the mechanical adaptor removably fits over the window to form a substantially gas tight chamber of predefined volume defined by the walls of the mechanical adaptor and the instrument, means disposed in the mechanical adaptor for receiving a vial of test gas and breaking a seal in the vial to admit the test gas to the chamber. The invention is also directed to a kit including the vial of test gas, and a method for testing a gas detection instrument utilizing the apparatus and a vial of test gas.

Abstract: An apparatus for providing a test gas to a gas monitoring instrument having a window for admitting gas to a gas sensor therein, is formed from a mechanical adaptor open at a portion thereof and having walls adapted to the gas monitoring instrument such that the mechanical adaptor removably fits over the window to form a substantially gas tight chamber of predefined volume defined by the walls of the mechanical adaptor and the instrument, means disposed in the mechanical adaptor for receiving a vial of test gas and breaking a seal in the vial to admit the test gas to the chamber. The invention is also directed to a kit including the vial of test gas, and a method for testing a gas detection instrument utilizing the apparatus and a vial of test gas.

Abstract: A system and method for detecting the presence of submicron sized particles in a sample taken from the environment includes a collecting a sample from the environment and purifying and concentrating the submicron particles in a sample based on the size of the particles. The purified and concentrated particles are detected with an apparatus which includes an electrospray assembly having an electrospray capillary, a differential mobility analyzer which receives the output from the capillary, and a condensation particle device for counting the number of particles that pass through the differential mobility analyzer.

Abstract: An ultrasonic inspection reference standard for composite materials includes a prism that is manufactured from a polymer resin. The ultrasonic inspection reference standard may be a rectangular prism and may be a polymer resin step-wedge reference standard that has similar acoustic properties as prior art fiber-reinforced composite step-wedge reference standards at significantly lower manufacturing cost. A photo-polymer resin reference standard may be created using a stereo lithography process. The polymer resin reference standard may replace a currently used expensive fiber-reinforced composite reference standard. The ultrasonic inspection reference standard manufactured from a polymer resin may be used, for example, for ultrasonic inspection of fiber-reinforced composite parts. The polymer resin reference standard may be used, for example, in the aircraft airframe industry, both commercial and defense.

Abstract: A leak test arrangement having a leak calibration device is disclosed. The calibration device is connected into communication with the leak test arrangement and provides a controlled source (sink) of fluid at a predetermined amount. The calibration includes a substantially sealed volume of fluid in fluid communication with the test arrangement and a control arrangement for heating and/or cooling the volume to produce the source (sink) of the calibrator.

Abstract: An osmolarity measuring system comprising microscale electrode arrays is configured to account for variations and defects in the arrays using a tiered approach comprising several calibration methods. One method accounts for the intrinsic conductivity of the electrodes and subtracts out the intrinsic conductivity on a pair-wise basis, when determining osmolarity of a sample fluid. Other methods in the tiered approach use standards to determine calibration factors for the electrodes that can then be used to adjust subsequent osmolarity measurements for a sample fluid. The use of a standard can also be combined with a washing step.

Abstract: A self-calibrating carbon dioxide sensor that includes a carbon dioxide detector and a carbon dioxide gas generator. In some embodiments, the carbon dioxide gas generator includes a heating element and a carbon dioxide gas releasing solid material in thermal communication with the heating element. The carbon dioxide gas releasing solid material releases carbon dioxide when heated by the heating element. Methods of calibrating a self-calibrating carbon dioxide sensor are also disclosed.

Abstract: A reference leakage device for a leak sniffer detector that is equipped with a sniffing tip and a control unit. The reference leakage device includes a gas reservoir and a constriction wherefrom there is released a specific amount of test gas, at least during calibration. A sensor is located in the constriction for detecting the approach of the sniffing tip wherein the device further is capable of transmitting signals to control unit of the leak detector.

Abstract: The present invention relates to testing equipment 20 for a fire alarm 1. It includes a testing pole (21), a range spacer (23) connected to the testing pole (21), and a reflective means and/or scattering means situated in the inside of the essentially pot-shaped designed range spacer (23).

Abstract: The present invention relates to a method for mathematically re-calibrating and adjusting an initial concentration analysis model that suffers from electrochemical measurement errors caused by surface state changes in the working/counter/reference electrode after extended usage. Specifically, such recalibration method reimburses long-term drift in the electrochemical measurements based on a single point testing.

Abstract: A gas sensor includes a gas detector, a reference gas generator, and a circuit. The reference gas generator includes a heater and a gas releasing material. The gas releasing material is in proximity to the heater such that, when the heater is energized during calibration, the gas releasing material releases an overpressure of a reference gas to the gas detector and such that, when the heater is not energized, the gas releasing material releases no substantial overpressure of the reference gas to the gas detector. The circuit energizes the heater during calibration and is responsive to an output of the gas detector during the period when the gas detector is provided the reference gas so as to calibrate the gas sensor.

Abstract: A self-testing and self-calibrating detector utilizing an internally produced reference gas. A detector that is sensitive to a target analyte as well as a reference gas can be utilized. A gas releasing material, such as a heated metal hydride, releases the reference gas. The partial pressure of the reference gas is known as a temperature dependent physical property of the gas releasing material. During calibration, the material can be heated to release reference gas and a calibration measurement of the gas' partial pressure can be made and compared to an expected value. The comparison can then be utilized to calibrate the detector.

Abstract: The self-calibrating carbon monoxide detector and method of the present invention utilize the gas for which the detector was designed to detect as the calibration gas. Specifically, a carbon monoxide gas generator is included in the detector assembly, and is controller to produce a known amount of CO. The sensor response to the quantity of CO generated is monitored, and the calibration thereof adjusted as necessary. The operation of the gas generator is also monitored, and any failures are flagged for user attention. The gas generator specifically suppresses the generation of hydrogen through the materials used in its construction. Temperature effects may also be compensated either through control of gas generation control parameters or compensation of the sensor output in view of the generator temperature effects.

Abstract: The present invention provides a method of calibrating sensors within a gas detector (36) having a housing containing a gas inlet whereby gas can diffuse from the inlet to the sensors. The gas inlet in the housing is held against part (34) of the calibration apparatus to form a sealed gas interface between the apparatus and the detector; a source (10) of pressurized calibration gas is connected to the apparatus, and a predetermined dose of calibration gas is delivered to the interface between the detector (36) and the calibration apparatus (34) at a predetermined pressure. The source (10) of pressurized calibration gas may contain single or multiple calibration doses and, if the former, the calibration apparatus includes a dosing system such as cylinder (14) for metering individual doses of calibration gas.

Abstract: A reference sample for testing fire detectors and a method of testing utilizing the reference samples. The reference sample comprises a fused mixture of pellets of the plastics usually found in aircraft cargo holds, with a heating element embedded in the sample. The pellets are in a plurality of layers with the composition of each layer being homogeneous but the thicknesses and porosities of the layers differing from each other. When the heating element is energized the layers of pellets, which have previously been fused into porous masses, begin to smolder, thereby generating a smoky atmosphere that as nearly as possible simulates the atmosphere in an aircraft cargo hold when there is a fire in the hold. In addition, a flammable liquid can be poured onto the sample and ignited, simultaneously with the energization of the heating element, by a separate ignition source to provide a flaming fire atmosphere.

Abstract: The present invention relates to a method for investigating the behavior of particles or droplets in a gas-vapor mixture inside a flow device, which is useful for studying cloud dynamical and microphysical processes. The invention allows adjustment and/or control of the thermodynamic system parameters based on the observed behavior of an internal standard with known properties, thus achieving a well-defined vapor concentration and saturation field inside the flow device. By injecting particles or droplets to be investigated into this well defined flow device, and measuring the size of the particles or droplets, the activation and growth or shrinking behavior of the particles or droplets may be determined using a mathematical model of the fluid, thermodynamic, and chemical conditions of the flow device.

Abstract: A combined manufacturing machine and certifying system are operable for performing a first operation of the machine, obtaining first data by quantifying the first operation of the machine using first measurement equipment of known accuracy, performing a second operation of the machine, obtaining second data by quantifying the second operation of the machine using second measurement equipment, determining the accuracy of the second measurement equipment by quantifying the difference between the first and second data, machining a first workpiece with the machine after determining the accuracy of the second accuracy measurement equipment, performing a third operation of the machine after machining the first workpiece, and obtaining third data by quantifying the third operation of the machine using the second accuracy measurement equipment.

Abstract: A chemical adsorption system and method comprising an apparatus containing a solid adsorption article comprising a known amount of a chemical adsorbate material disposed on a solid adsorbent material. Trace amounts of the adsorbate are released from the adsorbent using an inert gas. By controlling various parameters such as the temperature of the adsorption article, the amount of the adsorbate on the adsorbent, and the flow rate of inert gas through the apparatus, the amount of chemical adsorbate material vapor that is released from the adsorbent can be precisely controlled and predicted. The apparatus contains no liquid chemical materials, and serves as both an internal chemical reference standard to the attached chemical vapor monitor and as a chemical surface passivator. Furthermore, the invention is capable of spanning several orders of magnitude in chemical vapor concentration from the parts-per-million (ppm) to parts-per-trillion (ppt) range.

Abstract: An apparatus for calibrating a particulate matter continuous emission monitoring system includes: a feed unit that supplies particulate matter of a known mass flow rate; an eductor unit connected with the feed unit that receives particulate matter therefrom; a fluidizing unit connected to the eductor that supplies gas to the eductor unit, wherein the particulate matter and gas are combined into a fluidized mixture; and a probe connected to the eductor configured to extend within an industrial stack and deliver the fluidized mixture therein. Such an apparatus can provide accurate data regarding particulate matter concentration that can be compared with readings on the PM CEMS and enable a calibration curve to be generated. A tracer gas injection unit and analyzer may also be included.

Abstract: The invention relates to a cartridge for packaging an analyte-containing fluid calibrant. The cartridge is formed from a container having an opening sealed by a sealing member. A septum divides the container into a calibrant compartment and an outer compartment. A probe is provided comprising an analyte-detecting portion and a connecting portion that allows for operative connection to a device for quantitating or determining the concentration of the analyte. The probe may extend sealingly through the septum such that the analyte-detecting portion is located in the calibrant compartment and the connecting portion is located in the outer compartment. The construction of the cartridge provides ease and reduces the likelihood of error in calibrating the probe. The invention also relates to a method of manufacturing the cartridge and a method for calibrating a device for analyte concentration determination and quantitation using the inventive cartridge.

Abstract: The invention relates to a cartridge for packaging an analyte-containing fluid calibrant. The cartridge is formed from a container having an opening sealed by a sealing member. A septum divides the container into a calibrant compartment and an outer compartment. A probe is provided comprising an analyte-detecting portion and a connecting portion that allows for operative connection to a device for quantitating or determining the concentration of the analyte. The probe may extend sealingly through the septum such that the analyte-detecting portion is located in the calibrant compartment and the connecting portion is located in the outer compartment. The construction of the cartridge provides ease and reduces the likelihood of error in calibrating the probe. The invention also relates to a method of manufacturing the cartridge and a method for calibrating a device for analyte concentration determination and quantitation using the inventive cartridge.

Abstract: A test leak unit (1) includes a supply of test gas, preferably helium, and an element (14) for determining leakage rates. The aim of the invention is to create a simple, robust and easily refilled test leak unit, especially for detecting packaging leaks. To this end, the test gas supply is stored under substantially atmospheric pressure in a resealable reservoir (2) including a closing part (3), such that when the reservoir (2) is closed, a test gas-impermeable seal is developed between the closing part (3) and the reservoir (2), and the leakage rate-determining element (14) forms part of the closing part (3).

Abstract: A reference sample for testing fire detectors and a method of testing utilizing the reference samples. The reference sample comprises a fused mixture of pellets of the plastics usually found in aircraft cargo holds, with a heating element embedded in the sample. The pellets are in a plurality of layers with the composition of each layer being homogeneous but the thicknesses and porosities of the layers differing from each other. When the heating element is energized the layers of pellets, which have previously been fused into porous masses, begin to smolder, thereby generating a smoky atmosphere that as nearly as possible simulates the atmosphere in an aircraft cargo hold when there is a fire in the hold. In addition, a flammable liquid can be poured onto the sample and ignited, simultaneously with the energization of the heating element, by a separate ignition source to provide a flaming fire atmosphere.

Abstract: A combined manufacturing machine and certifying system are operable for performing a first operation of the machine, obtaining first data by quantifying the first operation of the machine using first measurement equipment of known accuracy, performing a second operation of the machine, obtaining second data by quantifying the second operation of the machine using second measurement equipment, determining the accuracy of the second measurement equipment by quantifying the difference between the first and second data, machining a first workpiece with the machine after determining the accuracy of the second accuracy measurement equipment, performing a third operation of the machine after machining the first workpiece, and obtaining third data by quantifying the third operation of the machine using the second accuracy measurement equipment.

Abstract: A portable breath test simulator including a case having a jar support arm extending to one side of the top of the case. A jar containing a known water-alcohol solution is mounted on the bottom of the arm. The case and jar support the simulator. A magnetic power drive located in the case to one side of the jar rotates a magnetic stirrer in the jar. Breath blown into the jar forms an effluent having a known concentration of alcohol and is flowed to a breath test analyzer to be tested.

Abstract: A method for compensating for baseline or span drift in gas sensing equipment includes obtaining gas concentration data over a time period and identifying a quiescent period within that time period. The method compares a component concentration corresponding to the quiescent period with one or more additional component concentrations relating to different quiescent periods and calculates an estimated background gas concentration for a predetermined number of time periods. The estimated background concentration is then compared to a preset, or expected, background concentration, and a correction value is calculated. For baseline drift, a correction value is determined to be the difference between the estimated background concentration and the present (expected) background concentration. For span drift, a correction value is determined to be the ratio of the estimated background concentration to the preset (expect) background concentration.

Abstract: A method of self-testing a semiconductor chemical gas sensor comprises the steps of: applying power to a heating element; obtaining a measurement from a temperature sensing element; adjusting the power applied to the heating element until the obtained measurement from the temperature sensing element reaches a desired measurement; obtaining a measurement from a gas sensitive element when the desired measurement is reached; and comparing the obtained measurement from the gas sensitive element to a reference measurement. An alternate method comprises the steps of: applying power to the heating element; obtaining measurements from the gas sensitive element and the temperature sensing element; adjusting the power applied to the heating element to cause a change in the obtained measurement from the temperature sensing element and obtaining a change in measurement from the gas sensitive element; and determining if the obtained change in gas measurement is consistent with the change in temperature measurement.

Abstract: A method and device for making measurements of the characteristics of a fluid, particularly the milk, which flows in pulsations in a conduit. The device has a measuring region wherein at least one characteristic of the fluid is determined. The measurement is made during an optimal measuring window which constitutes a time interval while a pulsation of the fluid is received in the measuring region which contains a sensor or sensors for measuring one or more selected characteristics of the fluid, such as color, conductivity or acoustic qualities. The measuring region may be in a bypass passageway in the conduit which may be incorporated in a teat cup. The pulsations in the teat cup may be used to define an optimal measuring window for measuring one or more characteristics of the fluid as it flows in pulsations through the conduit. The sensed entry or approach of a pulsation into the measuring region may also be used to define the optimal measuring window.

Abstract: A chromatography detection system can handle the flow from a chromatography column. The chromatography detection system has an injection valve and a detector for detecting emissions from a flowing sample. The injection valve has at least one loop and is adapted to connect to the chromatography column. The valve can (a) load the at least one loop independently of the chromatography column in a first mode, and (b) serially connect the least one loop between the chromatography column and the detector in a second mode. Thus, flow from the at least one loop to the detector is driven by eluate from the chromatography column.