Enzyme immunochromatography--a quantitative immunoassay requiring no instrumentation.

1985 ◽  
Vol 31 (7) ◽  
pp. 1144-1150 ◽  
Author(s):  
R F Zuk ◽  
V K Ginsberg ◽  
T Houts ◽  
J Rabbie ◽  
H Merrick ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Matrix Effects ◽  
Biological Fluids ◽  
Test Strip ◽  
Paper Strip ◽  
Assay Result ◽  
Quantitative Immunoassay ◽  
Colored Zone ◽  
Enzyme Conjugate ◽  
Instrumental Methods

Abstract We describe a novel test-strip immunoassay for quantifying drugs in biological fluids. This enzyme immunochromatographic ("immunograph") method combines many features of the enzyme-channeling homogeneous immunoassay with immunochromatography and capillary migration to provide a non-separation, non-instrumental assay for theophylline in which quantification is based on the spatial distribution of enzyme label rather than on the modulation of enzyme activity. Sample antigen and hapten-enzyme conjugate are combined and moved by capillary action up a paper strip on which specific antibody has been immobilized. After color development, the assay result is evaluated by measuring the height of the colored zone on the test strip. Quantification is not a function of enzyme activity, so the method is relatively insensitive to sample matrix effects, enzyme instability, temperature, and incubation timing. Either whole blood or plasma can be used as sample. Results correlate well with those by established instrumental methods. The simple, rapid (15 min), two-incubation protocol is well suited for on-site testing in non-laboratory environments.

scholarly journals Enhanced Surveillance of Foodborne Mycotoxins by Immunochemical Assay

1988 ◽  
Vol 71 (6) ◽  
pp. 1075-1081 ◽  
Author(s):  
James J Pestka
Keyword(s):  
Quality Control ◽  
Solid Phase ◽  
Protein Conjugates ◽  
Sample Extract ◽  
Large Numbers ◽  
Wide Range ◽  
Enzyme Conjugate ◽  
Aflatoxin B ◽  
Sampling Procedures ◽  
Instrumental Methods

Abstract Mycotoxins are a chemically diverse group of fungal secondary metabolites with a wide range of toxic effects. Conventional thin-layer and instrumental methods of mycotoxin analysis are time-consuming and make routine safety and quality control screening of these compounds in agricultural commodities difficult. As an alternative, specific polyclonal and monoclonal antibodies have been raised against mycotoxin-protein conjugates and used in sensitive radioimmunoassays (RIAs) and enzyme-linked immunosorbent assays (ELISAs). One of the simplest ELISA approaches involves competition for a solid-phase antibody between a mycotoxin-enzyme conjugate and an unconjugated mycotoxin in the sample extract. ELISAs have been developed for aflatoxins B, and M„ zearalenone, T-2 toxin, and deoxynivalenol, which are highly specific, rapid (10 min), easily adaptable for analyzing large numbers of samples, and directly applicable to assaying methanol-water extracts of a wide range of foods. Several commercial mycotoxin ELISAs using this approach (most typically for aflatoxin B,) are currently being marketed. Since ELISAs will be used in large part by personnel with limited technical expertise, individual kits must be critically evaluated by analytical chemists for suggested sampling procedures, efficiency of extraction, crossreactivity, mycotoxin recovery, assay reproducibility, and product shelf-life prior to routine use in food safety and quality control screening

Determination of enzyme activity in biological fluids by means of electrochemical oxidation of NADH at a modified glassy carbon electrode.

1984 ◽  
Vol 30 (11) ◽  
pp. 1780-1783 ◽  
Author(s):  
L Bartalits ◽  
G Nagy ◽  
E Pungor
Keyword(s):  
Enzyme Activity ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Biological Fluids ◽  
Enzyme Reaction ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Significant Difference ◽  
Anodic Peak Current

Abstract This amperometric technique for the determination of enzyme activity is based on detecting a decrease in the concentration of the NADH co-factor of the enzyme reaction. A glassy carbon electrode, modified by adsorption of Mg2+ and NADH, is used to measure the anodic peak current that corresponds to the oxidation of NADH. We found no significant difference between the enzyme activity of lactate dehydrogenase (E.C.1.1.1.27) preparations as measured by the above amperometric technique and by a spectrophotometric method.

Personal Observations

1986 ◽  
Vol 30 ◽  
pp. 29-33
Author(s):  
Ron Jenkins
Keyword(s):  
Transition Period ◽  
Matrix Effects ◽  
Analytical Tool ◽  
X Ray Diffraction ◽  
X Ray ◽  
General Acceptance ◽  
Methods Of Analysis ◽  
The Matrix ◽  
Instrumental Methods

Like most instrumental methods of analysis, X-Ray Fluoresence (XRF) has progressed through the various stages of Innovation, Frustration, Application and Consolidation. My own association with the method dates back to the late 1950's which would correspond to the transition period between the innovation and frustration stages alluded to above. At that time, there were probably less than 500 XRF spectrometers in the whole world and to myself, as a young analyst with a limited background in x-ray diffraction methods, the potential power which the XRF method seemed to offer far outweighed any problems from the ‘matrix effects' that people were starting to talk about. This talk covers my own impressions of the highlights of the 20 year period of frustration and application which were to culminate with the general acceptance of the XRF method, in the mid-1970's, as a versatile and reliable analytical tool.

Centrifugal analyzer used for enzyme immunoassay of progesterone and choriomammotropin.

1983 ◽  
Vol 29 (2) ◽  
pp. 302-304 ◽  
Author(s):  
B Terouanne ◽  
J Marchand ◽  
C Calzolari ◽  
J Monnier ◽  
J C Nicolas ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Affinity Chromatography ◽  
Enzyme Immunoassay ◽  
Gel Filtration ◽  
Placental Lactogen ◽  
Human Placental Lactogen ◽  
Rapid Separation ◽  
Enzyme Conjugate ◽  
Enzyme Label ◽  
Free Antigen

Abstract Recently we developed an enzyme immunoassay involving the use of steroid delta-isomerase (EC 5.3.3.1) as enzyme label and exclusion-affinity chromatography for rapid separation of free antigen-enzyme conjugate that bound to antibodies (J. Immunol. Methods 35: 267-284, 1980). Here we describe an automated version of this procedure, for immunoassay of progesterone and choriomammotropin (human placental lactogen) in serum with the use of a centrifugal analyzer. After incubation, suitable dilutions of sera or extract plus antiserum, conjugate, and double antibody were filtered on an estradiol affinity gel-filtration column; the enzyme activity of the filtrates was determined with the centrifugal analyzer. Results correlate well with those obtained by radioimmunoassay: r (progesterone) = 0.980, r (choriomammotropin) = 0.940. The within-run and between-run precision, specificity, sensitivity, accuracy, and speed of this system make it a useful tool for immunoassay.

scholarly journals Enhanced plasma persistence of therapeutic enzymes by coupling to soluble dextran

1977 ◽  
Vol 164 (2) ◽  
pp. 461-464 ◽  
Author(s):  
R F Sherwood ◽  
J K Baird ◽  
T Atkinson ◽  
C N Wiblin ◽  
D A Rutter ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Gel Filtration ◽  
Single Peak ◽  
Tumour Bearing ◽  
Enzyme Conjugate ◽  
Covalently Linked ◽  
Therapeutic Enzymes

Conjugation of carboxypeptidase G and arginase, two enzymes of therapeutic interest, to a soluble dextran significantly enhanced plasma persistence in normal and tumour-bearing mice. A prolonged decrease in arginine concentrations in plasma of tumour-bearing mice was demonstrated by using the dextran-linked arginase. Gel filtration of dextran-enzyme conjugate showed that enzyme activity co-chromatographed as a single peak with carbohydrate, and enzyme was shown to be covalently linked to the dextran.

A noninstrumented quantitative test system and its application for determining cholesterol concentration in whole blood

1990 ◽  
Vol 36 (9) ◽  
pp. 1591-1597 ◽  
Author(s):  
M P Allen ◽  
A DeLizza ◽  
U Ramel ◽  
H Jeong ◽  
P Singh
Keyword(s):  
Hydrogen Peroxide ◽  
Whole Blood ◽  
Biological Fluids ◽  
Test Strip ◽  
Indicator System ◽  
Test System ◽  
Cholesterol Concentration ◽  
Blood Specimens ◽  
Finger Stick ◽  
Sample Measurement

Abstract A novel noninstrumented technology has been developed for quantifying analytes of clinical interest in biological fluids. Application of this technology is exemplified by the development of a quantitative cholesterol test with performance equivalent to state-of-the-art instrumented methods. The assay chemistry combines two separate processes located in different areas of a test strip: enzymatic action on serum cholesterol to produce hydrogen peroxide (5 x 10 mm enzyme reagent pad) and quantification of the hydrogen peroxide (5 x 70 mm measurement region). Color bands are formed in the measurement area through the use of a redox-coupled indicator system. The height of the color band on the strip is directly proportional to the sample cholesterol concentration. A one-step cassette contains all components necessary to run the test and includes blood filtration and automatic sample measurement, so that unmeasured finger-stick whole-blood specimens can be analyzed by the non-technically trained user. The test is complete in less than 15 min, is read visually like a thermometer, and gives results that are in excellent correlation with established instrumented methods.

scholarly journals Minimizing interferences in the quantitative multielement analysis of trace elements in biological fluids by inductively coupled plasma mass spectrometry

1997 ◽  
Vol 43 (12) ◽  
pp. 2303-2311 ◽  
Author(s):  
Chiung-Sheng Hsiung ◽  
Joseph D Andrade ◽  
Robert Costa ◽  
K Owen Ash
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Matrix Effects ◽  
Biological Fluids ◽  
External Calibration ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Target Values ◽  
Plasma Mass Spectrometry ◽  
Urine And Serum

Abstract The determination of trace and ultratrace elements in biological fluids, including urine and serum, by inductively coupled plasma mass spectrometry (ICP-MS) is discussed. Nonspectral interferences and their corrections by external calibration and calibrator addition are discussed in detail. External calibration with internal calibration and dilution is mostly sufficient to correct for encountered biological matrix effects. For some elements, such as Cs and Zn, the use of calibrator addition provides more accurate results. The importance of spectral interferences and their elimination by isotope selection was also studied. Two examples, Cu and Zn, demonstrate the prime importance of selecting an isotope with minimal polyatomic interferences for analysis. By using 65Cu and 68Zn, accurate results for urine and serum can be obtained without excessive pretreatment of samples. Two reference materials, Bio-Rad Lyphochek urine and Kaulson Contox sera, were analyzed. Accuracy was evaluated by comparison with target values, and precision was estimated by the CV within 95% confidence.

scholarly journals Overcoming the Effects of Matrix Interference in the Measurement of Urine Protein Analytes

2012 ◽  
Vol 7 ◽  
pp. BMI.S8703 ◽  
Author(s):  
Timothy P. Taylor ◽  
Michael G. Janech ◽  
Elizabeth H. Slate ◽  
Evelyn C. Lewis ◽  
John M. Arthur ◽  
...  
Keyword(s):  
Biomarker Discovery ◽  
Matrix Effects ◽  
Biological Fluids ◽  
Urine Protein ◽  
Effective Technique ◽  
Assay Performance ◽  
The Matrix ◽  
Urine Proteins ◽  
Urine Matrix ◽  
Multiplex Bead

Using multiplex bead assays to measure urine proteins has a great potential for biomarker discovery, but substances in urine (the matrix) can interfere with assay measurements. By comparing the recovery of urine spiked with known quantities of several common analytes, this study demonstrated that the urine matrix variably interfered with the accurate measurement of low abundance proteins. Dilution of the urine permitted a more accurate measure of these proteins, equivalent to the standard dilution technique when the diluted analytes were above the limits of detection of the assay. Therefore, dilution can be used as an effective technique for overcoming urine matrix effects in urine immunoassays. These results may be applicable to other biological fluids in which matrix components interfere with assay performance.

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