Abstract: Immunoassays featuring voltammetric measurements wherein at least one of the immunoreactants is labelled with an electroactive substance. Measurement is effectedon a pulsed-basis to maximize the signal change due to the electron transfer capabilities of the labelled immunoreactants.

Abstract: A multichamber cuvette for maintaining in independent and separate condition at least two reactants until such time that it is desired to mix them for reaction with each other and a reactant liquid sample while in the cuvette for analysis in the cuvette, and a method of use of such cuvette. There is provided a cuvette body of a suitable plastic defining at least two chambers interconnected by a passageway of relatively small cross section having at least the end portion thereof of capillary size to prevent under many circumstances, as by surface tension, accidental mixture of liquid reactants in the chambers. If there is a substantial head of liquid in one chamber and/or a risk of impact of the cuvette with an external foreign object, sufficient to break such surface tension, an air lock in the passageway when the latter is below the liquid levels in the chambers prevents such accidental mixture. A baffle in the passageway enhances separation of liquids and/or solid substances in the chambers.

Abstract: A disposable integrated miniaturized array of chemical sensors for analyzing concurrently a number of analytes in a fluid sample is described. Each sensor is a complete electrochemical cell consisting of its own individual reference and indicator electrodes and is selective with respect to a particular analyte in the sample.Where required, a sensor can be individually calibrated, such that each analysis can be read directly.

Abstract: A carbohydrate substrate such as starch for a carbohydrate hydrolyzing enzyme is immobilized on a solid inorganic porous support to form a stable substrate-support composite useful in affinity chromatography and in methods where a precise amount of substrate is needed to perform an enzyme-substrate reaction to quantify the enzyme. The substrate may be activated with an agent such as cyanogen bromide or imidazole prior to deposition on the support so that it may be effectively modified while on the support. After deposition, the substrate is modified by reaction with an epoxyhalogen, aliphatic dihalide or aliphatic diamine to aid in holding it on the support. In an alternative embodiment, the carbohydrate, prior to deposition and modification on the support, is hydrolyzed with an enzyme, preferably dextranase.

Abstract: New and improved method and apparatus for the non-invasive detection of the respective segments and segment interfaces, and the non-invasive determination of the respective segment volumes, of a continuous segmented fluid stream flowing in a transparent conduit are disclosed and comprise means to irradiate the conduit and the flowing fluid stream with radiation energy of spectral content predetermined in accordance with the radiation energy absorbance and refraction characteristics of the fluid segments and the fluid segment-conduit interface, means to detect the radiation energy which is transmitted through the segments and conduit and provide signals indicative thereof, and signal processing means operatively associated with the detecting means and operable to process said signals and perform the stated functions in accordance therewith.

Abstract: A method of producing an immobilized protein composite, i.e. enzymes such as glucose oxidase, on an alumina support, comprising modifying some of the free functional groups of the protein such as amino groups, by reaction with an acid or anhydride, depositing the modified protein on a porous inorganic support at controlled pH and temperature, and cross-linking remaining free functional groups of the protein with adjacent deposited protein functional groups to form interprotein peptide bonds. The resultant composite has long-term continuous use.

Abstract: A system for detecting live insects in a commodity sample features forming a closed-loop between a stored quantity of fluid and a sample cell and a reference cell. The closed-loop and the stored fluid ensure a controlled environment during incubation and analysis of the commodity sample. This controlled environment achieves a greater sensitivity and reproducibility than prior systems.

Abstract: An apparatus and method for increasing the throughput of a chromatographic system by passing several samples in seriatim through tandemly connected first and second chromatographic columns. The eluant from the first column is sampled, or fractionated, and fractions of each of the samples are passed through the second column for further separation. A switching of the sampling valve, disposed between the first and second columns, effects such fractioning. The pumping rate for the second column may be different from that of the first column and allows that two or more sample fractions can occupy the second column concurrently.

Abstract: A class of reagents are synthesized from an aminobenzaldehyde base compound. The reagents are stable, sensitive, and useful in quantitative and qualitative analyses for: primary aromatic and aliphatic amines, reactive compounds containing methylene and amido (e.g., urea) groups; amino acids, enzymes, and immunoreactants.

Abstract: A method for producing an immobilized protein composite, particularly using enzyme and non-enzyme proteins, comprising selecting at least a first protein which is rich in cysteine and/or cystine amino acid residues, and a second protein which is poor in cysteine and/or cystine amino acid residues. These two proteins are deposited on an inorganic support and maintained at a pH and temperature for sufficient time to facilitate the copolymerization of the two proteins.

Abstract: Apparatus and method for determining the concentration of a constituent in a sample using chromatographic and optical measuring techniques. A sample containing a constituent to be analyzed is fractionated by a chromatographic column. A light beam is passed through the constituent fraction in the column, and the light absorbance (or transmittance) is measured. The fluid carrier (or solvent) eluting through the column will generally increase the transmissivity of the light passing through the column due to a difference between the indices of refraction of the carrier fluid and the chromatographic packing material. Such increased transmissivity will generally offset any decrease in the transmittance due to trace amounts of the constituent in the sample. The optical measurement is compensated to nullify such increased transmissivity, so as to allow measurement of such trace amounts of constituents.

Abstract: A method and reagents are disclosed for minimizing interference from halide ions in ion-selective electrode analysis. A reagent consisting of a mixture of a metal and a chelating agent is introduced to the fluid sample being analyzed. This reagent forms soluble complexes with halide ions in the fluid sample, thus minimizing their effects.

Abstract: This invention relates to a method for purifying a carbohydrate containing enzyme which is a desired enzyme preferred to be separated from a mixture. The method comprises the steps of mixing a solution containing the carbohydrate containing enzyme with a carbohydrate modifying reagent. The carbohydrate modifying reagent reacts with the carbohydrate attached to the enzyme, thereby modifying its chemical structure. The modified enzyme is then separated from the other undesirable enzymes or proteins in the mixture by a suitable chemical separation method, for example, gel filtration chromatography. The method was used in the separation of glucose oxidase from catalase, a separation which by previous methods was very inefficient.

Abstract: The presence of antibodies (Ab) and antigens (Ag) in a liquid is detected by mixing the liquid with two different particulate reagents which mutually agglutinate but whose agglutination is inhibited by the particular Ab or Ag under assay. By detecting the extent of agglutination, the presence or absence of the Ab or Ag can be confirmed. By measuring the extent of agglutination or non-agglutination quantitatively, an amount of Ab or Ag can be determined. The particulate reagents preferably comprise latex.

Abstract: An electrochemical system using a flow-through electrode design employing a dual separation method to lower electrode poisoning due to large chemical species and interference current due to small electroactive species is disclosed. The system includes a fluid inlet to a reaction chamber and a fluid outlet from the chamber, with the chamber in contact with an electrode system. The electrode is protected from poisoning and interference by a membrane system comprising a semipermeable membrane having well defined pore ranges therethrough which allow diffusion of only selected size small molecules. A unique sample stream flow control coupled with the size selective membrane combine to remove large, or macromolecule poisoning species and substantially reduce small species interference at the active surfaces of the electrode means.

Abstract: This invention relates to a method and apparatus for rapid quantitative determination of .alpha.-amylase in aqueous samples such as blood serum, etc. The method comprises a flow-through of the sample through various immobilized reagents contained in sequential stages. A scavenger stage initially removes glucose originally present in the sample and comprises immobilized glucose oxidase and catalase. The glucose-free sample flows through an immobilized starch stage substrate preferably containing a high percentage of amylose to quantitatively react with the .alpha.-amylase in the sample and produce oligosaccharides. The sample with the oligosaccharides flows through a glucose-generating stage containing immobilized glucoamylase which converts the oligosaccharides to glucose. The glucose-containing sample enters a detection stage wherein the glucose is converted to H.sub.2 O.sub.2 by flowing through immobilized glucose oxidase, and the H.sub.2 O.sub.

Abstract: This invention relates to a method and apparatus for rapid quantitative determination of .alpha.-amylase in aqueous samples such as blood serum, etc. The method comprises a flow-through of the sample through various immobilized reagents contained in sequential stages. A scavenger stage initially removes glucose originally present in the sample and comprises immobilized glucose oxidase and catalase. The glucose-free sample flows through an immobilized starch stage substrate preferably containing a high percentage of amylose to quantitatively react with the .alpha.-amylase in the sample and produce oligosaccharides. The sample with the oligosaccharides flows through a glucose-generating stage containing immobilized glucoamylase which converts the oligosaccharides to glucose. The glucose-containing sample enters a detection stage wherein the glucose is converted to H.sub.2 O.sub.2 by flowing through immobilized glucose oxidase, and the H.sub.2 O.sub.

Abstract: In the analysis of liquids, particularly biological liquids such as serum or urine, mouse serum or a component of mouse serum is used as a reagent. The reagent has the ability to combine with antibody:antigen complexes (but not free antibody or antigen) and to combine with IgG and IgM. It differs markedly from human C1q in that it remains active at high pH and in the presence of certain substances known to destroy human C1q. It is a very broadly applicable reagent in immunoassays, and particularly useful in techniques involving agglutination latex particles.

Abstract: An apparatus and method for regenerating a degenerated curve, which curve has approximately degenerated exponentially. The apparatus, in part, comprises a sampler for sampling in a real time sense the points on the degenerated curve, a memory for storing the obtained samples, and an arithmetic unit for determining the points on a regenerated curve.

Abstract: Substituted hydantoin drugs (for example phenytoin) and tricyclic antidepressant drugs (for example nortriptyline) are assayed by mixing them with a fluorescent labelled compound and antibodies, and measuring the fluorescence of the mixture. The assay does not necessitate any separation step and may be effected by continuous-flow techniques.