Abstract: Methods for determining the concentration of an analyte in a sample in which an analyte gradient is established and brought into contact with one or more zones that contain binding members that interact with the analyte and thereby produce a detectable signal. Devices that may be used to practice the disclosed methods are also provided.

Abstract: A device and related method for simultaneously performing a plurality of immunoassays to detect the presence of respective analytes in a sample. The device involves the use of a unitary bibulous material providing one or more flow paths having a common origin site and a plurality of respective reagent zones providing the reagents necessary for performing a visual read-out, competitive immunoassay for the presence of the respective analyte.

Abstract: A solid phase capable of detecting the presence of nicotine and/or nicotine metabolites is described. The solid phase is impregnated with assay reagents including a color determinant, a buffer, a cyanogen releasing agent and a cyanogen halide forming agent. The solid phase provides a means whereby unprocessed urine samples over a wide range of different pH values can be tested for the presence of nicotine and/or nicotine metabolites. The assay results may be determined by direct visualization of the color of the solid phase. Also described are methods of preparing and using the solid phase, and kits containing the solid phase.

Abstract: A method of monitoring compliance of a patient that has been placed on a medication maintenance program with a prescribed medication dosage by determining a normalized urine medication concentration. An unadulterated urine sample is obtained from the patient. The urine medication concentration and urine specific gravity are measured. The normalized urine medication concentration is calculated as a function of the measured medication concentration in the urine and the urine specific gravity. The calculated normalized urine medication concentration is compared with an expected medication concentration value for the patient for the maintenance program prescribed to determine any significant differences therebetween as an indication of noncompliance. Alternatively, a urinary-parameter normalized urine medication concentration is calculated as a function of the measured medication concentration in the urine, the urine specific gravity and at least one selected pharmacokinetic parameter of the medication.

Abstract: Immunoassays of psychoactive drugs including psychotomimetic drugs, narcotic drugs, and tetrahydrocannabinols and treatment methods based on the antigenic properties of protein conjugates of these drugs. These methods are based upon treating the psychoactive substances as haptens and utilizing their protein conjugates to produce antibodies to the psychoactive materials themselves. The immunoassay methods include both agglutination and agglutination-inhibition reactions. The treatment methods include treatment or both exogenous, administered drugs (such as cannabinols, LSD, heroin and morphine) and endogenous substances (such as N,N-Dimethyltryptamine and 5-Methoxy-N,N-Dimethyltryptamine by active immunization and also passive immunization.

Abstract: Novel reagents for the detection by immunoassay of drugs in body fluids, their preparation and use are disclosed. The reagents of the present invention correspond to the formulaP--[A--D].sub.nwhere:D is a drug derivative suitably selective for the determination of the presence of the target drug or drug metabolite,A is an activating linker-spacer group having an N-hydroxysuccinimide or isothiocyanate derived linking moiety,P is a poly(amino acid) or polymer capable of covalently bonding with A, andn is less than l.

Abstract: Immunoassay methods and reagents for the specific quantification of amitriptyline or nortriptyline in a test sample are disclosed employing antibodies prepared with amitriptyline or nortriptyline derivatives of the Formula III: ##STR1## wherein for amitriptyline, R is CH.sub.3, and for nortriptyline, R is H. The present invention also describes the synthesis of unique fluorescein tracers of the structure of Formula IV and Formula V: ##STR2## wherein for a specific amitriptyline immunoassay, W.sub.1 is a heteroatom linked to the aromatic ring at the 2 or 3 position, and for a specific nortriptyline immunoassay, W.sub.2 is two heteroatoms linked together and attached to the aromatic ring at the 2 or 3 position, and wherein Q is a detectable moiety, preferably fluorescein or a fluorescein derivative.

Abstract: The present invention is directed to novel opiate derivatives which are synthesized for the covalent attachment to antigens (proteins or polypeptides) for the preparation of antibodies or receptors to the opiates and opiate metabolites. The resulting novel antigens may be used for the production of antibodies or receptors using standard methods. Once generated, the antibodies or receptors and the novel derivatives which are covalently attached to proteins, polypeptides or labels may be used in the immunoassay process.

Abstract: The invention is directed to labeled drug hapten analogues comprising:(A) a label, of the type used in immunoassays, having an amine or sulfhydryl group;(B) a drug hapten nucleus selected from barbiturates or hydantoins and(C) a linking chain linking the 3-position of the drug hapten nucleus to the label through a carbonyl bridge.

Abstract: A improved method for preparing a concentrated meconium extract containing basic and acid-neutral target analytes present in a meconium sample suspected of containing the target analytes is provided. The meconium sample is extracted with a mixed solvent of acetonitrile and a volatile organic acid and the resulting organic phase is separated. The organic phase is diluted with water to provide an organic solution which is passed through a mixed mode solid phase extraction column having strong cation exchange and hydrophobic functionality. Acid-neutral and basic target analytes are sequentially eluted from the column and the eluates are combined to form a combined extract. The combined extract is evaporated to dryness and reconstituted in buffer to provide a clean concentrated neonatal meconium extract for use in qualitative and quantitative analyses.

Abstract: A method for reducing or eliminating tyramine interference from amphetamine and methamphetamine immunoassays, comprising treating the sample with aqueous tyramine oxidase for a time and at a temperature and pH sufficient to deaminate any tyramine present in the sample, is provided.

Abstract: A labelling color for detecting cocaine of Formula (I) ##STR1## wherein X represents a halogen, and a method of detecting methamphetamine, including the steps of adding a labelling color of Formula (II) ##STR2## wherein X represents an anion to a first solution of methamphetamine antibody to form a labelling color-methamphetamine antibody complex, measuring the fluorescence of the first solution, adding a sample containing an unknown amount of methamphetamine to the first solution to form a second solution, measuring the fluorescence of the second solution, and correlating any change in the fluorescence between the first and second solutions to the concentration of methamphetamine in the sample.

Abstract: An alstonine composition is useful as a selective marker of tumor cells and/or of chromosomal aberrations, and for the detection thereof by measurement of fluorescence at about 375 nm. Thus, an alstonine preparation can be used as a diagnostic agent designed for selective detection of tumoral diseases, and in cytogenetics. The diagnostic agent has application in preoperative, peroperative and postoperative diagnoses.

Abstract: Specific binding ligands can be detected with an assay which utilizes an immobilized receptor for the ligand, a reporter enzyme, an inhibitor antibody and an anti-inhibitor antibody. Both antibodies are specific for the reporter enzyme. The inhibitor antibody effectively shuts down the activity of the reporter enzyme when it is complexed thereto. The anti-inhibitor antibody binds to the reporter enzyme, does not affect the enzymatic activity, but prevents the binding of the inhibitor enzyme. This assay provides a direct correlation of the target specific binding ligand to the signal generated without the use of separation or wash steps.

Abstract: Assay for detecting the amount or presence of target ligand in a sample. The assay includes a ligand analogue conjugate having a linkage site and a binding site, a ligand receptor, and a sample. The assay includes the steps of providing at least one crosstalk inhibitor. This inhibitor, under assay conditions, competes with the linkage site of the ligand analogue conjugate for binding to the ligand receptor, and does not compete with the binding site of the ligand analogue conjugate for binding to the ligand receptor. In the invention, the assay is performed for the target ligand in the presence of a sufficient amount of the crosstalk inhibitor to reduce the amount of binding of the linkage site of the ligand analogue conjugate to the ligand receptor. The invention also features a method for identifying crosstalk inhibitors, and the crosstalk inhibitors themselves.

Abstract: The present invention relates to immunoassay methods for detecting and measuring the amount of an analyte in a sample by means of generic anti-hapten antibodies. Also disclosed are multi-analyte immunoassay methods. Reagents, devices, and kits using the anti-hapten antibodies are also disclosed. The present invention also relates to immunoassay methods for detecting and measuring the amount of an analyte in a sample by means of a dual antibody format.The present invention also relates to dyed erythrocytes, preferably fixed, which are coated with antibodies. Also disclosed is the use of these dyed erythrocytes in agglutination assays to detect and measure the presence of an analyte in a sample. The analyte can be a hapten, an antigen, or an antibody. Also included are agglutination assays, compositions and kits using these dyed and coated erythrocytes.

Abstract: Assay reagents, devices, methods and kits used in the analysis of low molecular weight analytes which by themselves are too small or unable to bind to two specific binding members at the same time. The invention involves the use of an analyte-substitute reagent (ASR) comprising at least two components, the first of which is identical to or an analog of the analyte to be determined, while the second is an unrelated ligand for which an antibody or other specific binding member can be obtained or produced.

Abstract: The present invention provides a novel immunoassay for the detection of multiple analytes such as amphetamine and methamphetamine in a single assay of a biological fluid sample. In this assay, a single labelled binding partner is utilized capable of cross reacting at differing sensitivities to antibodies derived from conjugate derivatives of the different analytes such that the presence of the analytes at selected levels of concentration of the analytes singly or in combination can be detected.

Abstract: This invention relates to novel quaternary ammonium immunogenic conjugates and reporter reagents useful for eliciting antibodies and in immunoassays. Processes for preparing such quaternary ammonium immunogenic conjugates and their use in immunoassays and in eliciting antibodies are also disclosed.

Abstract: A system and method of determining absence or presence of an illicit substance in a flowing mixture of requisite reagents by agglutination or lack thereof. A plurality of photodetectors are positioned over an illuminated read area oblique to a path of the flowing mixture. Signal samples of each of the detectors are processed individually. Successive samples are processed over a period time to detect differences or edges between relatively clear liquid and relatively opaque clusters in the flowing mixture. The illicit substance is determined in accordance with the number of variations in signal samples for a predetermined number of detectors.

Abstract: A method for the treatment of the symptoms of fescue toxicosis in mammals comprising injecting a subject mammal with a vaccine which includes from about 5 .mu.g to about 1 mg of a protein-alkaloid conjugate per mL of a physiologically acceptable carrier. There is also provided a vaccine for the treatment of the symptoms of fescue toxicosis and a compound for preparing that vaccine.

Abstract: A phosphorescence assay system. The phosphorescent label for immunoassays is palladium (II) octaethylporphine alphaisothiocyanate. The labeling agent has a Stokes shift of not less than 150 nanometers. Method for preparing the palladium (II) phosphorescent label is also shown.

Abstract: The present invention relates to an apparatus for conducting a variety of assays that are responsive to a change in the viscosity of a sample fluid and relates to methods of conducting such assays. In particular, the present invention is related to the use of a cartridge for conducting one or more coagulation assays or, conversely, fibrinolysis assays. The disclosed device enjoys simplicity and is adaptable to the point-of-care clinical diagnostic area, including use in accident sites, emergency rooms, surgery or intensive care units.

Abstract: A surface ionization detector for detecting organic molecules such as illicit drugs and non-organo-nitrate explosives includes a heated surface and a collector electrode. A sample containing trace amounts of the organic molecules in ambient air is directed over the heated surface maintained at a temperature in the range of 500.degree. C. to 800.degree. C., thereby causing the molecules to decompose into fragments. A polarization voltage between 18 V and 24 V is applied to ionize the fragments which are then collected by the collector electrode. An electrometer connected to the collector electrode measures the current and a change in the current indicates the presence of ionized fragments, and thereby indicates the presence of the organic molecules. The temperature of the heated surface and the polarization voltage are optimized for detection of particular organic molecules.

Abstract: Non-primate or primate cells are provided comprising a functional human transporter for neurotransmitter uptake. The cells allow for dissection of the mechanism of neurotransmitter transport, as well as screening for agonists and antagonists of the neurotransmitter with respect to its uptake. Methods are provided for producing such cells. Specifically, the cells are transformed with human DNA comprising the gene encoding for the neurotransmitter transporter, whereby this protein(s) is expressed and incorporated into the plasma membrane and is capable of functioning to transfer the neurotransmitter from the extracellular space to intracellular domains. The physiological, kinetic and pharmacological characteristics of transport in these cells conform to known characteristics of high-affinity neurotransmitter transport in the CNS.

Abstract: A novel bidentate conjugate has two different chemical moieties, or bidentate members, attached through an adequate spacer moiety. Each bidentate member acts as a small molecule ligand and is capable of specifically binding to a different macromolecular substance. The bidentate members are relatively small molecules, usually less than about 7,000 Daltons in size. The spacer moiety is selected so that both bidentate members can simultaneously bind to their respective specific binding partners. Where the specific binding partners are multivalent, large complexes can be formed. The formation of these complexes can be inhibited by the presence of an unconjugated monovalent bidentate member, such as free analyte from a test sample. The bidentate is of particular use in turbidimetric or nephelometric inhibition immunoassay procedures.

Abstract: A method of tagging and detecting illicit drugs or paper currency is disclosed which comprises the steps of:(a) applying a Perfluorocarbon Tracer (PFT) to the drugs or currency such that said PFT is released over a period of time as a vapor taggant; and(b) subsequently detecting the presence of said vapor taggant, and therefore the drugs or currency.

Abstract: The present invention is directed to a fluorescence polarization assay for phencyclidine and phencyclidine derivatives, to the various components needed for preparing and carrying out such an assay, and to methods of making these components. Specifically, tracers, immunogens and antibodies are disclosed, as well as methods for making them, and a reagent kit containing them. The tracers and the immunogens are made from substituted phencyclidine compounds. A fluorescein moiety is included in the tracer, while a poly(amino acid) forms a part of the immunogen. The assay is conducted by measuring the degree of polarization retention of plane polarized light that has been passed through a sample containing antiserum and tracer.

Abstract: A labelling color which includes a pentamethine of the following formula (1): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each are a C.sub.1-6 alkyl group, and X is an anion.

Abstract: A fluorescence polarization immunoassay (FPIA) for detecting the presence of one or more amphetamine-class analytes in a test sample is provided. The immunoassay uses competition between the analyte and a fluorescently labeled tracer for the binding site on an antibody specific for phenethylamine derivatives. The concentration of amphetamine-class analyte in the sample determines the amount of tracer that binds to the antibody. The amount of tracer-antibody complex formed can be quantitatively measured and is inversely proportional to the quantity of analyte in the test sample. The invention relates to tracers, to immunogens used to elicit antibodies for use as assay reagents, and to assay kits incorporating these tracers and assay reagents.

Abstract: Assay reagents, devices, methods and kits used in the analysis of low molecular weight analytes which by themselves are too small or unable to bind to two specific binding members at the same time. The invention involves the use of an analyte-substitute reagent (ASR) comprising at least two components, the first of which is identical to or an analog of the analyte to be determined, while the second is an unrelated ligand for which an antibody or other specific binding member can be obtained or produced.

Abstract: The precision of identification of analyte composition in a sample, where the possible analytes cross-react with specific binding reagents, is enhanced by applying pattern recognition techniques. Samples to be tested are reacted with a panel of specific binding reagents reactive with the set of analytes to be tested to obtain a pattern of reactivity with respect to each analyte at a given concentration. This results in a databank of "CRIM profiles" for known concentrations of each analyte. This databank is stored in a computationally accessible form, which then can be matched against CRIM patterns obtained by testing unknown samples. In one embodiment, each CRIM pattern obtained is plotted as a single point in n-dimensional space, wherein n represents the number of specific binding reagents in the panel.

Abstract: Divalent hapten derivatives wherein two hapten moieties are connected by means of a bifunctional spacer wherein the derivative has the formulaA--X--Awhere A is a bonded hapten moiety and X is a bifunctional spacer having the formula(B).sub.m --Y--(CH.sub.2).sub.n --Z--(CH.sub.2).sub.n --Y--(B).sub.mwhere m is independently 0 or 1, B is (CH.sub.2).sub.n', wherein n' is an integer from 1 to 4, or CO(CH.sub.2).sub.n", wherein n" is an integer from 2 or 4; Y is independently --CONH--, --NHCO--, --OOC, --COO--, --O--, --S--, or --NR--, wherein R is hydrogen or alkyl; n is an integer from 1 to 10; and Z is an organic moiety containing at least one hydrophilic atom, useful for the determination of haptens by immunochemical techniques are disclosed.

Abstract: The instant invention is directed toward an immunoassay which can determine the presence of amphetamines in a sample suspected of containing amphetamine and/or methamphetamine by employing at least two conjugates, each comprised of a functionally similar label bound to an amphetamine analog and a methamphetamine analog respectively and an antibody to amphetamine and an antibody to methamphetamine wherein at least one of the antibodies is a monoclonal antibody.

Abstract: A method for the direct analysis of analyte in keratinized structures, e.g., hair, fingernails and toenails, which comprises preparing a mixture containing a low redox potential compound such as dithiothreitol or dithioerythritol, an enzyme suitable for the degradation of the keratin structure and a sample of the keratin structure; permitting the enzyme to at least substantially degrade the sample of keratin structure, and subjecting the mixture to analysis to determine the identity and amount of analyte in the keratin substance sample. To accelerate the method, cupric sulfate or sodium arsenite may be added to the mixture after degradation of the keratin sample. The enzyme may be a peptidase, endopeptidase or proteinase, with papain, chymopapain, and proteinase K being preferred for use in the invention.

Abstract: Novel derivatives of phencyclidine are provided as precursors for conjugating to antigenic proteins for the preparation of antibodies which bind to phencyclidine or conjugation to enzymes for use as reagents in immunoassays. The combination of the antibodies and enzyme conjugates provide a sensitive and rapid assay for phencyclidine.

Abstract: The present invention relates to immunoassay methods for detecting and measuring the amount of an analyte in a sample by means of generic anti-hapten antibodies. Also disclosed are multi-analyte immunoassay methods. Reagents, devices, and kits using the anti-hapten antibodies are also disclosed. The present invention also relates to dyed erythrocytes, preferably fixed, which are coated with antibodies. Also disclosed is the use of these dyed erythrocytes in agglutination assays to detect and measure the presence of an analyte in a sample. The analyte can be a hapten, an antigen, or an antibody. Also included are agglutination assays, compositions and kits using these dyed and coated erythrocytes.

Abstract: A method and apparatus for selective, high speed detection of vapors of specific gas-chromatographically-separable compounds. In the disclosed method separate analyses are performed on two portions of a gas sample formed by flash-heating trapped vapors to successively higher temperatures while flowing hydrogen carrier gas over coatings in/on which the vapors are held. Within a total time interval of about twenty seconds 1) two sample portions are formed, 2) each portion is rapidly separated in two series-connected, high speed, temperature-programmed gas chromatographs, and 3) specific compounds are identified by detection of NO gas formed during an oxidative pyrolysis of each separated portion. One application of the described method and apparatus is the rapid, selective, and sensitive detection of nitrogen-containing compounds such as the drugs methamphetamine, cocaine, and heroin.

Abstract: This disclosure relates to a method and reagents for determining amphetamine and d-methamphetamine in a biological fluid, such as urine. In particular, this disclosure relates to improvements in a fluorescence polarization immunoassay procedure for determining the presence of amphetamine and d-methamphetamine in a single assay and to a novel class of tracer compounds employed as reagents in such procedures. The procedure described includes pretreatment of the biological sample to eliminate cross reactants such as .beta.-hydroxyphenethylamine by preincubating the sample solely with an aqueous periodate solution having a pH from about 4.0 to about 7.5 without adjustment to an alkaline pH, and contacting the sample with riboflavin binding protein to reduce interference from fluorescent components in the sample. The procedure also maintains the cross reactivity of the immunoassay for tyramine at about 0.4% and for 1-methamphetamine below about 5.

Abstract: A method and device for testing for the presence of substances such as drugs in body fluids while simultaneously positively identifying the test subject. The device comprises an absorbent pad and a membrane mounted to the absorbent pad containing a plurality of separated areas provided with different immobilized ligand having a specific receptor site for capture or rejection of specific antigens produced by different predetermined drugs.

Abstract: An immunofluorescent assay method, characterized in using an immunodetective reagent, which is an antigen-like substance comprising a fluorescent substance and an antigen chemically bonded thereto with or without intervention of an additional chemical bond, said fluorescent substance being changed in the wavelength or intensity of the fluorescence when an antibody comes close thereto, and said antigen being specific to said antibody.

Abstract: A method for determining the presence of a predetermined minimum detectible amount of one or more analytes in a sample suspected of containing the analyte is disclosed. Each analyte is a member of a specific binding pair ("sbp member") consisting of ligand and its complementary receptor. The method comprises contacting with a test solution containing said sample and predetermined amounts of two or more of a plurality of first sbp members, each respectively analogous to one of said analytes, a contact portion of a piece of bibulous material capable of being traversed in at least one direction by the test solution by capillary migration. The bibulous material contains predetermined amounts of two or more of a plurality of second sbp members, each respectively capable of binding one of the analytes and corresponding first sbp member.

Abstract: Methods for determining the presence of a first ligand, preferably a hapten, in a sample suspected to contain the first ligand are provided, along with reagent systems and apparatus suitable for performing the methods. The methods depend upon a color visualization indicating the presence or absence of the first ligand in the sample. Preferred methods comprise contacting the sample with a reagent system which comprises: (1) colored particles which bear on their surface a second ligand which may be the same as or different than the first ligand; and (2) an amount of a receptor which is specific for the first ligand and the second ligand, wherein the amount is sufficient to stabilize the particles. The methods further comprise passing the contacted sample and reagent system through a filter, and then analyzing the color of the filtrate. The presence of ligand in the sample is established where the color of the filtrate is substantially different from the color of the ligand-bearing particles.

Abstract: A fluorescence immunoassay method is described in which the presence or absence of antigen is measured within one minute by measuring a variation in fluorescence emitted from an antibody. The method comprises reaction between a pseudo-antigen obtained by chemical combination of an antigen and a fluorescent quencher and an antibody by which fluorescence to be emitted from the antibody is quenched by the action of the quencher combined. When an analyte is added to a solution of the combination, the pseudo-antigen is replaced by an antigen if the analyte contains the antigen, so that the fluorescence increases in intensity. This intensity is measured and compared with the initially measured intensity to detect the presence of the antigen. The method does not make use of the action of antigen on antibody with respect to the fluorescence of the antibody and is applicable to all antigens.

Abstract: The present invention is directed to a fluorescence polarization assay for phencyclidine and phencyclidine derivatives, to the various components needed for preparing and carrying out such an assay, and to methods of making these components. Specifically, tracers, immunogens and antibodies are disclosed, as well as methods for making them. The tracers and the immunogens are made from substituted phencyclidine compounds. A fluorescein moiety is included in the tracer, while a poly(amino acid) forms a part of the immunogen. The assay is conducted by measuring the degree of polarization retention of plane polarized light that has been passed through a sample containing antiserum and tracer.

Abstract: A methodology is presented which relates in general to fluorescence polarization immunoassays (FPIA) and modifications of current processes wherein detection and quantification of several commonly abused or therapeutic drugs in a single biological fluid sample are determined utilizing manual or current software or related equipment to allow the sequential and simultaneous performance of more than one FPIA assay. The methodology involves combining the reagents either separately or pre-mixed, for multiple assays in a single reagent package, these reagents being used to assay quantitative amounts of each of the assay analytes in a sequential step manner. The assay being performed by mixing the sample with a combination reagent and then initiating a specific reaction for each of the separate analytes by sequentially adding a specific reagent, i.e.

Abstract: The present invention is directed to a fluorescence polarization assay for benzoyl ecgonine and substituted benzoyl ecgonine compounds in biological fluids, and to a method of making reagents therefor. Specifically, tracers, immunogens and antibodies are disclosed. The tracers and the immunogens are made from substituted benzoyl ecgonine compounds. A fluorescein moiety is included in the tracer, while a poly(amino acid) forms a part of the immunogen. The assay is conducted by measuring the degree of polarization retention of plane polarized light that has been passed through a sample containing antiserum and tracer.

Abstract: A novel bidentate conjugate has two different chemical moieties, or bidentate members, attached through an adequate spacer moiety. Each bidentate member acts as a small molecule ligand and is capable of specifically binding to a different macromolecular substance. The bidentate members are relatively small molecules, usually less than about 7,000 Daltons in size. The spacer moiety is selected so that both bidentate members can simultaneously bind to their respective specific binding partners. Where the specific binding partners are multivalent, large complexes can be formed. The formation of these complexes can be inhibited by the presence of an unconjugated monovalent bidentate member, such as free analyte from a test sample. The bidentate is of particular use in turbidimetric or nephelometric inhibition immunoassay procedures.

Abstract: An improved method for detecting the presence of durg metabolites in the meconium of newborn infants is described. The method involves a single step extraction of the drug metabolites from meconium using a buffered aqueous solution containing methanol in an amount between about 10 and 30% by volume and buffered to a pH between 6 and 7 and then assaying the extract individually for the presence of the drug metabolites. The method is particularly useful for detection of cocaine, morphine, cannabinoid and amphetamine metabolites; however, any drug metabolite in the infant meconium can be tested if it is extracted by the solution from the meconium. Various assay methods are used for the drug metabolites in the solutions derived from the meconium, including immunoassays, fluorescent assays and mass spectroscopy. The method provides for early detection of drug presence in newborn infants which contribute to infant illness.

Abstract: A method for determining the presence of a predetermined minimum detectible amount of one or more analytes in a sample suspected of containing the analyte is disclosed. Each analyte is a member of a specific binding pair ("sbp member") consisting of ligand and its complementary receptor. The method comprises contacting with a test solution containing said sample and predetermined amounts of two or more of a plurality of first sbp members, each respectively analogous to one of said analytes, a contact portion of a piece of bibulous material capable of being traversed in a least one direction by the test solution by capillary migration. The bibulous material contains predetermined amounts of two or more of a plurality of second sbp members, each respectively capable of binding one of the analytes and corresponding first sbp member.