Abstract: Methods and related apparatuses and mixtures are described for spectroscopic detection of hydrogen sulfide in a fluid, for example a formation fluid downhole. A reagent mixture is combined with the fluid. The reagent mixture includes metal ions for reacting with hydrogen sulfide forming a metal sulfide, and a capping agent that limits growth of the insoluble metal sulfide species by electrosteric or steric stabilization. The particle growth is one of chemical reaction or significant aggregation, and the capping agent further functionalizes the reagent mixture to exhibit properties outside the natural characteristics of the metal sulfide species to allow for spectroscopic detection of the metal sulfide species. The combined mixture and fluid is then spectroscopically interrogated to detect the presence of the metal sulfide thereby indicating the presence of hydrogen sulfide in the fluid. The mixture also includes chelating ligands for sustaining thermal endurance of the mixture under downhole conditions.

Abstract: A method of determining a kind of a sample, in a method for analyzing a substance by the steps of supplying the sample to be analyzed to a reaction system by a supplying means comprising a transparent region composed of a transparent material, reacting a reagent for detecting the substance with the sample in the reaction system, and analyzing a signal derived from a product obtained by the reaction, characterized by irradiating the transparent region with light in the supplying step, and analyzing an optical intensity of the light.

Abstract: A method of correction of particle interference to hemoglobin measurement of a blood sample on a hematology analyzer is provided. The method includes mixing an aliquot of a blood sample with a lytic reagent to lyse red blood cells and forming a sample mixture; measuring absorbance of the sample mixture at a predetermined wavelength of a hemoglobin chromogen formed in the sample mixture, and obtaining an apparent hemoglobin concentration of the blood sample using obtained absorbance; measuring concentration and size of cellular particles remaining in the sample mixture; removing contribution of the cellular particles to the apparent hemoglobin concentration using the concentration and the size of the cellular particles to obtain a corrected hemoglobin concentration of the blood sample; and reporting the corrected hemoglobin concentration of the blood sample.

Abstract: A sensor for use in detecting and analyzing predetermined chemical substances is presented.

Abstract: The present invention relates to the field of detection of components in gas phase, and in particular to detection of nitric oxide exhaled as a component of breath, using a liquid crystal assay format and a device utilizing liquid crystals as part of a reporting system.

Abstract: A microfluidic system including a chip sensor and an SPR optical detector. The chip sensor may be made a non-transparent material, such as polyimide or silicon, allowing non-visible radiation produced by the SPR optical detector to pass through and interact with a surface plasmon generating layer on the chip sensor.

Abstract: The present invention describes a system and method for accurately measuring the concentration of a substance within a filter housing. A concentration sensor and a communications device are coupled so as to be able to measure and transmit the concentration of a particular substance within the filter housing while in use. This system can comprise a single component, integrating both the communication device and the concentration sensor. Alternatively, the system can comprise separate sensor and transmitter components, in communication with one another. In yet another embodiment, a storage element can be added to the system, thereby allowing the device to store a set of concentration values. The use of this device is beneficial to many applications. For example, the ability to read concentration values in situ allows integrity tests to be performed without additional equipment.

Abstract: Systems and methods are described for measuring pH of low alkalinity samples. The present invention provides a sensor array comprising a plurality of pH indicators, each indicator having a different indicator concentration. A calibration function is generated by applying the sensor array to a sample solution having a known pH such that pH responses from each indicator are simultaneously recorded versus indicator concentration for each indicator. Once calibrated, the sensor array is applied to low alkalinity samples having unknown pH. Results from each pH indicator are then compared to the calibration function, and fitting functions are extrapolated to obtain the actual pH of the low alkalinity sample.

Abstract: An apparatus for measuring the concentration of carbon dioxide in water that can correct a reduction in measurement accuracy based on deterioration of a pH indicator is provided. A carbon dioxide concentration measurement apparatus includes a deterioration determining section that measures a change rate ?A0 of an isosbestic point absorbance A0 and determines that the pH indicator solution is deteriorated when the change rate ?A0 is reduced by a predetermined reduction rate or more. After the deterioration determining section determines deterioration of the pH indicator solution, a pH value computing section computes the pH value of the pH indicator solution using a corrected pH computation expression for correcting a deterioration of the pH value of the pH indicator solution on the basis of the change rate ?A0 of the isosbestic point absorbance A0.

Abstract: A direct rapid automated protein analyzer is disclosed. The protein analyzer includes means for reducing protein samples to small particles, a reaction vessel in material transfer communication with the homogenizer, a reservoir for binding dye composition in fluid communication with the reaction vessel, a metering pump in fluid communication with the reservoir and the reaction vessel for distributing discrete predetermined amounts of a binding dye composition to the reaction vessel, a filter in fluid communication with the reaction vessel for separating solids from filtrate after a dye binding reaction has taken place in the reaction vessel, and a calorimeter in fluid communication with the filter and the reaction vessel for measuring the absorbance of the filtrate from the reaction vessel and the filter. The rapid analyzer can be used in conjunction with a kit that includes a sample cup for mixing a protein sample with a dye-binding solution and a filter holder for being positioned in the sample cup.

Abstract: A use composition monitor determines the concentration of peracid and/or peroxide in a use composition using a kinetic assay procedure. A sample mixture containing a sample of the use composition, a diluent and at least one reagent is prepared and analyzed using, for example, an optical detector. A reduced-turbulence optical detector can be used to improve collected response data. A reduced-turbulence optical detector can include a cell body disposed about a length of transparent tubing. The cell body positions one or more emitter/receiver pairs about the transparent tubing. Thus, tube junctions are eliminated and sample flow within the tube is substantially turbulence free.

Abstract: An apparatus for analyzing an aqueous solution, as may be implemented with a hand-held portable electronic device (10) and test element (16). A test pad (32) of the test element responsive in color to a characteristic of an aqueous solution is interrogated by the device by measuring intensity values of an interrogating test light as reflected off of the test pad. The test pad may be supported on an opaque and non-reflective substrate (28) that cooperates with an opaque edge portion (14E) of a test element placement member (14B) and associated side walls (14W) of the device to minimize the impingement of ambient light onto the test pad during interrogation.

Abstract: The present invention describes a system and method for accurately measuring the concentration of a substance within a filter housing. A concentration sensor and a communications device are coupled so as to be able to measure and transmit the concentration of a particular substance within the filter housing while in use. This system can comprise a single component, integrating both the communication device and the concentration sensor. Alternatively, the system can comprise separate sensor and transmitter components, in communication with one another. In yet another embodiment, a storage element can be added to the system, thereby allowing the device to store a set of concentration values. The use of this device is beneficial to many applications. For example, the ability to read concentration values in situ allows integrity tests to be performed without additional equipment.

Abstract: A method for identifying a platelet population, preferably a population of immature, reticulated platelets, in a biological sample involves incubating the biological sample for less than 5 minutes with at least one labeled, ligand (e.g., monoclonal antibody) that binds to an epitope or antigen on platelets and with a nucleic acid dye. In one embodiment, the dye is Acridine Orange and the label on the ligand is PE-Cy7. The sample is then analyzed and one or more platelet populations is rapidly identified or quantified by passing the incubated sample through a sensing region of a flow cytometer. In one embodiment, this method occurs without a washing or physical cell separation step. The incubated sample is irradiated with a laser light source, and fluorescence of the labeled ligand and the nucleic acid dye are measured along with at least one additional parameter, e.g., light scatter, direct current, axial light loss, opacity, radio frequency, and fluorescence.

Abstract: Bodily fluid is analyzed for the presence of drugs of a selected panel of drugs in a simultaneous assay in which sample of the fluid is incubated with additional amounts of all drugs of the panel, antibodies specific to each of the drugs of the panel, and microparticles, the microparticles being divided into subsets, one subset for each drug in the panel and each subset distinguishable from the others. The incubation is performed in a liquid medium in which competitive binding occurs, the drugs in the sample competing with those added to the assay medium for binding to the antibodies. In one procedure, the added drugs are pre-coupled to the microparticles while the antibodies are not, and the incubation is followed by further incubating the microparticles with labeled ligands that have affinity for the antibodies.

Abstract: Methods of detecting a fusion analyte in a sample are provided. Aspects of the methods include preparing a reaction mixture that includes a sample and a microparticle comprising a capture ligand for the fusion analyte, as well as first and second fluorescently labeled detector molecules. One of the first and second detector molecules specifically binds to the fusion analyte and the other specifically binds to a parent molecule thereof. Also provided are systems and kits configured for use in practicing methods of the invention.

Abstract: A method for determining the hematocrit of a blood sample is provided that includes the steps of: 1) depositing the sample into an analysis chamber adapted to quiescently hold the sample for analysis, the chamber defined by the interior surfaces of first and second panels and a height extending there between, wherein both panels are transparent, and the height is such that at least some of the red blood cells within the sample contact both interior surfaces of the panels and one or more lacunae within the quiescent sample extend between the interior surfaces; 2) imaging at least a portion of the quiescent sample, which sample portion contains the red blood cells and one or more lacunae to determine an optical density of the imaged portion of the sample on a per image unit basis; 3) selecting and averaging the optical density values of the image units aligned with the red blood cells contacting the interior surfaces, and assigning an upper boundary value of 100% to the average optical density value of those im

Abstract: The enumeration of cells in fluids by flow cytometry is widely used across many disciplines such as assessment of leukocyte subsets in different bodily fluids or of bacterial contamination in environmental samples, food products and bodily fluids. For many applications the cost, size and complexity of the instruments prevents wider use, for example, CD4 analysis in HIV monitoring in resource-poor countries. The novel device, methods and algorithms disclosed herein largely overcome these limitations. Briefly, all cells in a biological sample are fluorescently labeled, but only the target cells are also magnetically labeled. The labeled sample, in a chamber or cuvet, is placed between two wedge-shaped magnets to selectively move the magnetically labeled cells to the observation surface of the cuvet. An LED illuminates the cells and a CCD camera captures the images of the fluorescent light emitted by the target cells.

Abstract: The invention relates to a microfluidic device comprising one or more fluid channels, one or more fluid ports, and a V-shaped particle retention structure. The fluid channel is generally opposite the particle retention structure, fluid ports are located between the fluid channel and the particle retention structure, and the particle retention structure has sloped side walls. Fluid, including reagents, can be delivered to the microfluidic device through the one or more fluid channels or the fluid ports. The invention also relates to methods of using the microfluidic device to monitor, observe, measure, or record a biological parameter of a particle, to separate a single particle from a group of particles, to culture a cell, to treat a particle, and to move a particle back and forth in the device.

Abstract: A fluid content monitor including a cuvette, a colorimeter adapted to generate a signal indicative of contents of a fluid sample contained in the cuvette, a container for holding a reagent, and a pump assembly for delivering reagent from the container to the cuvette. The pump assembly includes a tube extending from the container to the cuvette, check valves preventing reverse flow in the tube, and a hammer driven by a solenoid for repetitively compressing the tube to pump reagent to the cuvette. The cuvette can be removed for cleaning and replacement.

Abstract: A use composition monitor determines the concentration of peracid and/or peroxide in a use composition using a kinetic assay procedure. A sample mixture containing a sample of the use composition, a diluent and at least one reagent is prepared and analyzed using, for example, an optical detector. Response data obtained by the detector is indicative of the optical absorbance of the sample mixture as a function of time. A processor analyzes the response data to determine a corresponding best fit linear relationship. The initial absorbance of the sample mixture is indicative of the concentration of peracid in the use composition, while the slope of the best fit equation is indicative of the concentration of peroxide in the use composition.

Abstract: This disclosure relates to a dye solution monitoring device and a dye solution controlling device for a dye-sensitized solar cell, more particularly, to a dye solution monitoring device for a dye-sensitized solar cell comprising a light-absorption device for measuring absorbance of a dye solution for a dye-sensitized solar cell, and a pH measuring device for measuring pH of a dye solution for a dye-sensitized solar cell; and, a dye solution controlling device for a dye-sensitized solar cell further comprising a dye supply device supplying dye of high concentration, and an acid or base supply device for pH control, in addition to the monitoring device. According to the present invention, a dye adsorption process may be optimized in real time to manufacture a solar cell of high quality with high productivity, maximize utilization of expensive dye, and minimize the waste, thereby reducing production cost.

Abstract: The invention relates to an apparatus and method for adapting conventional spectrophotometer cuvettes for use in a vertical light beam spectrophotometer.

Abstract: It is an object of the present invention to provide an immunoassay method which is capable of simultaneous quantification of a plurality of test substances under a same analysis condition, through adjustment of the measurement sensitivity/range by simply varying the size of particles for use as labels, without changing the spectra of these particles.

Abstract: An imaging system includes a platform for placement of a sample or an animal to be imaged, and at least one excitation light source for irradiating the sample or animal to stimulate an emission at a plurality of different center wavelengths. An acousto-optic tunable filter (AOTF) is provided that includes a piezoelectric transducer crystal for emitting an acoustic wave having a ground electrode disposed on one side of the piezoelectric crystal. A patterned electrode layer is disposed on a side of the piezoelectric crystal opposite the ground electrode. The patterned electrode layer includes a continuous region proximate to its center and a discontinuous region, a pattern in the discontinuous region comprising a plurality of spaced apart features electrically connected to the continuous region, and an AO interaction crystal receiving the acoustic wave attached to the ground electrode or the patterned electrode layer.

Abstract: Chemical sensors whose active element exhibits both a visual change in color and a measurable change in electrical resistance when exposed to an analyte to which it selectively reacts are provided. These sensor have several unique features including vastly improved stability measured in years, irreversible visual changes and surprisingly reversible electrical changes. The combined unique features enable a new generation of ultra low power alerting, alarming and readout devices for hydrazines and other strongly reducing chemicals.

Abstract: Methods, compositions and articles of manufacture for assaying a sample for a target polynucleotide are provided. A sample suspected of containing the target polynucleotide is contacted with a polycationic multichromophore and a sensor PNA complementary to the target polynucleotide. A signaling chromophore absorbs energy from the excited multichromophore and emits light in the presence of the target polynucleotide. The methods can be used in multiplex form. Kits having reagents for performing such methods are also provided.

Abstract: An optical waveguiding optical format enables consistent optical analysis of small sample volumes with minimal variation in light path length among optical formats. The optical format is comprised of an input guide, an output guide, and a sample cavity adapted to allow light to pass through a sample on its way from the input guide to the output guide. A lid removed from the light pathway within the format may be provided with a reagent for assisting fluid analysis.

Abstract: It is an object of the invention to provide for an alternative for analyzing fluids. To this end a device for analyzing fluids comprising magnetic particles is provided, the device comprising magnetic means for generating a magnetic field designed for exerting a magnetic force to the magnetic particles creating a movement of the fluid comprising targets and a membrane with an array for moving the fluid through or along the array.

Abstract: Implementations of the present invention describe an apparatus for generating calibration factors for a spectral detector instrument. The calibration factors are derived from a calibration plate containing one or more spectral species in each well of the calibration plate. Each well is then exposed to an excitation source that causes the one or more spectral species in each of the wells to fluoresce. The signal response is measured and associated with each spectral species at each different well position in the calibration plate. Next, the measured signal response from each spectral species at each well position in the calibration plate is compared with a predetermined signal response for each spectral species. The results of this comparison can be used to determine a calibration factor for each well and spectral species to compensate for the difference between the measured signal response and the predetermined signal response.

Abstract: The present invention describes a system for accurately measuring the concentration of a substance within a filter housing. A concentration sensor and a communications device are coupled so as to measure and transmit the concentration of a particular substance within the filter housing while in use. This system allows the operator to certify the integrity of the filters within the filter housing at the customer site without additional equipment. In one embodiment, a tracer gas, such as helium or hydrogen, is added to a carrier and injected into the system. The concentration of tracer gas at a specific operating transmembrane pressure is indicative of bubble pointing specific pores in the filter. This test will give a more sensitive indication of the bubble point and the presence of defects than a standard diffusion test. In a second embodiment, two gasses, in a known ratio, are introduced into the filter housing.

Abstract: A light transmissive temperature control apparatus, a bio-diagnosis apparatus including the transmissive temperature control apparatus, and a method of diagnosing biochemical reaction using the bio-diagnosing apparatus are provided. The light transmissive temperature control apparatus includes at least one tube which is formed of a light transmissive material and configured to contain a sample; and a temperature control unit which accommodates at least a part of the at least one tube which is transparent, guides light to be irradiated onto the at least one tube, and controls a temperature of the at least one tube.

Abstract: The invention relates to a device for performing binding assays. In particular, the invention relates to a centrifugal device for performing such assays. The invention also relates to a method of performing binding assays involving antigen-antibody binding, nucleic acid hybridization, or receptor-ligand interaction.

Abstract: Systems and methods are described for measuring pH of low alkalinity samples. The present invention provides a sensor array comprising a plurality of pH indicators, each indicator having a different indicator concentration. A calibration function is generated by applying the sensor array to a sample solution having a known pH such that pH responses from each indicator are simultaneously recorded versus indicator concentration for each indicator. Once calibrated, the sensor array is applied to low alkalinity samples having unknown pH. Results from each pH indicator are then compared to the calibration function, and fitting functions are extrapolated to obtain the actual pH of the low alkalinity sample.

Abstract: A use composition monitor determines the concentration of peracid and/or peroxide in a use composition using a kinetic assay procedure. A sample mixture containing a sample of the use composition, a diluent and at least one reagent is prepared and analyzed using, for example, an optical detector. Response data obtained by the detector is used to determine the concentrations of peracid and/or peroxide in the use composition based upon an evaluation function determined by a calibration method. The calibration method includes determining coefficients of the evaluation function based upon known concentrations, and measured response data of calibration samples.

Abstract: A use composition monitor determines the concentration of peracid and/or peroxide in a use composition using a kinetic assay procedure. A sample mixture containing a sample of the use composition, a diluent and at least one reagent is prepared and analyzed using, for example, an optical detector. Response data obtained by the detector is indicative of the optical absorbance of the sample mixture as a function of time. A processor analyzes the response data to determine a corresponding best fit linear relationship. Depending upon an expected concentration range, the initial absorbance and/or the slope of the best fit equation are used to calculate the concentrations of the peracid and peroxide in the use composition.

Abstract: A method for the enumeration of micronucleated erythrocyte populations while distinguishing platelet and platelet-associated aggregates involves the use of a first fluorescent labeled antibody having binding specificity for a surface marker for reticulocytes, a second fluorescent labeled antibody having binding specificity for a surface marker for platelets, and a nucleic acid staining dye that stains DNA (micronuclei) in erythrocyte populations. Because the fluorescent emission spectra of the first and second fluorescent labeled antibodies do not substantially overlap with one another or with the emission spectra of the nucleic acid staining dye, upon excitation of the labels and dye it is possible to detect the fluorescent emission and light scatter produced by the erythrocyte populations and platelets, and count the number of cells from one or more erythrocyte populations in said sample.

Abstract: A method and sensor for the detection of luminescence radiation generated by at least one luminophore is disclosed.

Abstract: A use composition monitor determines the concentration of peracid and/or peroxide in a use composition using a kinetic assay procedure. A sample mixture containing a sample of the use composition, a diluent and at least one reagent is prepared and analyzed using, for example, an optical detector. A temperature stabilized optical cell is disclosed which enhance consistency of response data obtained from the optical detector, especially when the use composition monitor is utilized on site.

Abstract: This invention relates to a chemical sensing device for detecting an analyte. The device comprises a light source; at least one luminescent reagent which is capable of luminescing when irradiated by the light source wherein the luminescence of the luminescent reagent is modifiable by the analyte thereby changing the generation of heat, which change in heat generation is proportional to the concentration of the analyte, a transducer having a pyroelectric or piezoelectric element and electrodes which is capable of transducing the change in heat to an electrical signal, and a detector which is capable of converting the electrical signal into an indication of the concentration of the analyte. The invention also relates to a method for detecting an analyte.

Abstract: An improved chromatographic method for the separation, identification and quantification of contaminants associated with Eosinophelia-Myalgia Syndrome (EMS) includes a high pressure liquid chromatography (HPLC) method which utilizes a silica-based column and a gradient mobile phase. The method provides for effective, efficient, and economical quantitative and qualitative identification of 1,1?-Ethylidenebis L-tryptophan (EBT), 2,3-indolymethyl L-tryptophan (Peak 200), and 2-anilino-L-alanine (Peak 1).

Abstract: A microplate for use within an interrogation system and a method of using the microplate are disclosed. The microplate contains within the bottom of each well, an optical waveguide grating based sensor. Approximate to each sensor is a mask having an aperture of predetermined size. The aperture regulates the light that enters and exits the sensor upon successive scans and ensures repeatable readings from the sensor. In an extended embodiment, a method of detection is disclosed that utilizes a launch and receive system while employing the aforementioned microplate.

Abstract: The timing of the reaction of moisture-sensitive reagents for detecting the presence of analytes, e.g. leukocytes in urine samples, is used to detect when the reagents have been compromised by excess humidity. The ratio of light reflectance at wavelengths characteristic of the products of reaction between the reagents and the analyte and an infra-red reference dye is measured at two preset times after a urine sample has been applied to a test strip and used to determine whether the reagents have been compromised by excessive humidity. The presence of unusually dark samples is determined from the reflected light at 470 and 625 nm in order to confirm that the test strips are humidity-compromised.

Abstract: A system and method of characterizing an at least partially hydrophobic sample. The method includes providing an ethanolic solution of ethanol and sodium hydrogen cyanamide, adding a first portion of the ethanolic solution to a sample to produce a reagent-sample mixture, performing infrared spectroscopic testing of the reagent-sample mixture to generate mixture absorption data representing at least one absorption characteristic of the reagent-sample mixture, and generating acidity data for the sample based on the mixture data.

Abstract: A microfluidic circuit cartridge for a complete blood count, including analyses of red blood cells. Various parameters of the red blood cells may be attained. The cartridge may have sphering mechanism which has a channel or loop with a configuration for reducing or eliminating cell settling. The channel or loop may incorporate a combination of straight and curve paths in the context of gravity. The channel may alternatively have a hydrophilic or hydrophobic inside surface. Again alternatively, the channel may have an electro-wettable inside surface. Or, the channel may be subject to an electric or magnetic field. There may also be a mechanism for reducing or eliminating clumping of a sample.

Abstract: A channel chip includes a substrate made of a material capable of transmitting light. The substrate includes a groove to form a channel for allowing a fluid to flow. A film is made of a material capable of transmitting light. The film is bonded to the substrate with a pressure sensitive adhesive agent to seal the groove.

Abstract: The present disclosure describes an apparatus and associated method for quantifying the quality degradation of individual stored red blood cell (RBC) units, thereby yielding information to improve decisions regarding their respective allocation, patient suitability, and use. This apparatus and the methods of its use are amenable to clinical implementation as well as indicative of any given unit's relative viability and thus prospective efficacy. This would provide clinicians with actual data on RBC quality when making decisions about which and how many units to use for transfusion of a given patient. Moreover, deploying this testing throughout the supply chain will improve distribution, planning, and inventory control decisions. A vital aspect of this testing system is the accumulation of copious output and other associated data and the mathematical analyses thereof to optimize algorithms by which to characterize each subsequent test output as meaningfully as possible.

Abstract: The present invention relates to a method and an apparatus that measure the concentration of glycated hemoglobin by an optical technique. A wavelength in which the molecular extinction coefficient of oxyhemoglobin agrees or substantially agrees with the molecular extinction coefficient of deoxyhemoglobin is adopted as a measurement wavelength. Preferably, the measurement wavelength is set at from 417 to 421 nm. In the present invention, the concentration of glycated hemoglobin is measured by making use of column chromatography and of using a sample prepared from red blood cells in blood.

Abstract: There is provided a high-accuracy automatic analysis device achieving both of measurement in a wide concentration range and high sensitivity at a low concentration. The signals of a plurality of wavelengths ?1 to ?12 where the sensitivity of light absorption caused by fine particles is high from a light source 40 are converted to absorbances by a spectroscopic optical system (detector) 41. The absorbances are converted to a secondary parameter from in which a noise component is cancelled by using a previously-defined conversion table 54, so that a concentration of a measured material (predetermined component) is calculated by an operation unit (calculating means) 53 based on the secondary parameter. Thus, analysis being resistant to the noise even at the low concentration can be achieved in a range up to a high concentration.

Abstract: Disclosed herein is a reference electrode including an electrolyte containing an optically-active material, including: an electrode body provided at an end thereof with an electrolyte separation membrane and charged therein with an optically-active material and an electrolyte solution; an inner electrode disposed in the electrode body to be immersed in the electrolyte solution; and an absorbance measurement probe for transmitting light to the electrolyte solution and collecting reflected light waves, which is disposed in the electrode body to be immersed in the electrolyte solution. Since the concentration of an electrode reaction material, such as Cl?, in the electrolyte is calculated using the absorbance of the electrolyte solution containing the optically-active material, the change in potential of the reference electrode can be properly corrected even when the reference electrode is exposed to a test environment for a long period of time and thus the concentration of the electrolyte changes.