Enzyme immunoassay with flow-amperometric detection of NADH.

1982 ◽  
Vol 28 (9) ◽  
pp. 1848-1851 ◽  
Author(s):  
H M Eggers ◽  
H B Halsall ◽  
W R Heineman
Keyword(s):  
Clinical Laboratory ◽  
Amperometric Detection ◽  
Electrochemical Technique ◽  
Serum Samples ◽  
Laboratory Procedure ◽  
Detection Range ◽  
Optimum Detection ◽  
Routine Clinical Laboratory ◽  
Good Agreement

Abstract Using phenytoin as a model analyte, we demonstrate that an enzyme-coupled immunoassay based on flow-injection analysis and amperometric detection of NADH is both feasible and practical. Good agreement with a routine clinical laboratory procedure for phenytoin was obtained for patients' serum samples. The electrode must be protected to prevent fouling by proteins in the analytical sample. The optimum detection range for NADH was at 0.01 of the concentrations of NADH generated during the several minutes required for each analysis. This suggests that the electrochemical technique should be extendable to the determination of species at concentrations in the microgram per liter range.

Determination of plasma and erythrocyte lithium concentrations by atomic absorption spectrophotometry.

1977 ◽  
Vol 23 (1) ◽  
pp. 41-45 ◽  
Author(s):  
G H Hisayasu ◽  
J L Cohen ◽  
R W Nelson
Keyword(s):  
Atomic Absorption ◽  
Whole Blood ◽  
Room Temperature ◽  
Clinical Laboratory ◽  
Lithium Concentration ◽  
Atomic Absorption Spectrophotometry ◽  
Laboratory Procedure ◽  
Absorption Spectrophotometry ◽  
Routine Clinical Laboratory

Abstract We describe a method for determining plasma and erythrocyte lithium concentrations by atomic absorption spectrophotometry. Plasma and hemolyzed whole-blood are diluted and analyzed, with use of a lithium hollow-cathode lamp, at 670.8 nm. Erythrocyte lithium concentrations are calculated indirectly from the hematocrit. The standard deviation for a 0.43 mmol/liter pool of whole blood, run daily over 11 months, was +/-20 mumol/liter (CV=5.1). The lithium concentration of a lyophilized pool assayed periodically over the same period (n=127) was 1.84+/-0.05 mmol/liter (CV=2.7%). The relatively low erythrocyte/plasma lithium ratio and the microhematocrit centrifugation force (9600 to 13 600 X g) make corrections for trapped plasma insignificant. Problems with matrix matching and viscosity are overcome by using a plasma pool standard for calculations. Values for erythrocyte lithium concentrations were unchanged in samples stored at room temperature up to 24 h. Hemolysis appears to be of possible clinical significance. This method is useful as a routine clinical laboratory procedure for monitoring patients with affective disorders, who are undergoing therapy with lithium.

Determination of Thyroxine-Binding Globulin

1969 ◽  
Vol 15 (12) ◽  
pp. 1132-1140 ◽  
Author(s):  
R C Roberts ◽  
T F Nikolai
Keyword(s):  
Standard Deviation ◽  
Clinical Laboratory ◽  
Binding Capacity ◽  
Serum Samples ◽  
Thyroxine Binding Globulin ◽  
Total Thyroxine ◽  
The Mean ◽  
Routine Clinical Laboratory ◽  
Supernatant Solution

Abstract A method for determining thyroxine-binding globulin (TBG) concentration as the total thyroxine-binding capacity, has been developed. Prior electrophoretic separation of the three serum thyroxine-binding proteins is not required. Serum samples are diluted with a barbital-salicylate buffer pH 8.6, which inhibits thyroxine-binding by prealbumin. After incubation with 100 µg/100 ml thyroxine containing 131l-thyroxine, dextran-coated charcoal is added to the sample, which binds all the thyroxine not bound to TBG. The radioactivity in the supernatant solution is directly related to the concentration of TBG present. The Pearson’s correlation coefficient between the TBG results for this new assay and the polyacrylamide electrophoretic assay is 0.964. The mean TBG concentration and standard deviation for 80 normals was 19.2 ± 2.6 µg/100 ml. Pregnant women and women taking estrogens had a mean and standard deviation of 35.8 ± 4.8 µg/100 ml. Males from TBG-deficient families had TBG values of 5 µg/100 ml or less, and females from these families had values ranging from 8 to 12 µg/100 ml. The new assay is considerably simpler in equipment requirements and technic than the assays currently being used, and should be more practical for routine clinical laboratory use.

Electrochemical enzyme immunoassay for phenytoin by flow-injection analysis incorporating a redox coupling agent

1991 ◽  
Vol 37 (2) ◽  
pp. 245-248 ◽  
Author(s):  
Hua T Tang ◽  
H BrIan Halsall ◽  
William R Heineman
Keyword(s):  
Enzyme Immunoassay ◽  
Flow Injection ◽  
Flow Injection Analysis ◽  
Coupling Agent ◽  
Clinical Laboratory ◽  
Reduced Form ◽  
Clinical Samples ◽  
Laboratory Procedure ◽  
Routine Clinical Laboratory ◽  
Good Agreement

Abstract Using phenytoin as a model analyte, we demonstrate an electrochemical enzyme immunoassay based on flow-injection analysis and incorporating 2,6-dichloroindophenol (DCIP) as a redox coupling agent. DCIP reacts with NADH to form NAD+ and DCIPH2, the reduced form of the coupling agent. The production of DCIPH2 is monitored at +250 mV vs Ag/AgCl. This low applied potential improves selectivity in the biological matrix, differentiating against components that are oxidizable at the more-positive potentials required for direct electrochemical detection of NADH. The kinetics-based assay also eliminates other common interferences, mainly from ascorbic acid and glutathione. This system does not require precolumns or analytical columns for isolation of the NADH response. Good agreement with a routine clinical laboratory procedure for phenytoin is obtained for clinical samples (r = 0.95), illustrating the feasibility of such an approach.

scholarly journals Quantification of Serum Proteins Using Capillary Electrophoresis

1995 ◽  
Vol 32 (5) ◽  
pp. 493-497 ◽  
Author(s):  
M A Jenkins ◽  
M D Guerin
Keyword(s):  
Capillary Electrophoresis ◽  
Gel Electrophoresis ◽  
Serum Proteins ◽  
Clinical Laboratory ◽  
Charged Particles ◽  
Protein Electrophoresis ◽  
Agarose Gel Electrophoresis ◽  
Serum Samples ◽  
Routine Clinical Laboratory ◽  
Sample Dilution

Capillary electrophoresis is a technique that can be automated for the separation of charged particles. By investigating suitable sample dilution and injection time and adhering to a strict washing procedure we have been able to quantify paraproteins in serum samples. This has enabled us to use the technique of capillary electrophoresis for the provision of serum protein electrophoresis in a routine clinical laboratory. We present our findings of 260 serum samples, which included 76 samples with paraproteins analysed by both capillary electrophoresis (EC) and high resolution agarose gel electrophoresis (HRAGE). CE was able to detect all the monoclonal bands detected by HRAGE, and, in particular, better able to detect IgA monoclonal bands occurring in the beta region. The major advantages of CE over HRAGE relate to the automated nature of CE with the elimination of the need for a densitometer.

Adaptation of Babson's Method for the Determination of Serum Glutamic Oxalacetic Transaminase in the Clinical Laboratory

1965 ◽  
Vol 11 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Masaki Furuno ◽  
Albert Sheena
Keyword(s):  
Clinical Laboratory ◽  
Glutamic Oxalacetic Transaminase ◽  
Laboratory Workers ◽  
Routine Clinical Laboratory ◽  
Serum Glutamic Oxalacetic Transaminase ◽  
Final Color

Abstract Babson's method for the assay of serum glutamic oxalacetic transaminase (SGO-T) is modified to increase its accuracy and reliability. The final color produced is made stable with the addition of bisulfite ion, thereby making the procedure more suitable for the routine clinical laboratory. The 95% limits for values on 20 healthy laboratory workers was 4 to 26 units with a mean of 13 units.

scholarly journals Reagent-free, Simultaneous Determination of Serum Cholesterol in HDL and LDL by Infrared Spectroscopy

2002 ◽  
Vol 48 (3) ◽  
pp. 499-506 ◽  
Author(s):  
Kan-Zhi Liu ◽  
R Anthony Shaw ◽  
Angela Man ◽  
Thomas C Dembinski ◽  
Henry H Mantsch
Keyword(s):  
Ir Spectroscopy ◽  
Ldl Cholesterol ◽  
Clinical Laboratory ◽  
Hdl Cholesterol ◽  
Serum Samples ◽  
Clinical Method ◽  
Predicted Values ◽  
Friedewald Formula ◽  
Spectral Ranges

Abstract Background: The purpose of this study was to assess the feasibility of infrared (IR) spectroscopy for the simultaneous quantification of serum LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) concentrations. Methods: Serum samples (n = 90) were obtained. Duplicate aliquots (5 μL) of the serum specimens were dried onto IR-transparent barium fluoride substrates, and transmission IR spectra were measured for the dry films. In parallel, the HDL-C and LDL-C concentrations were determined separately for each specimen by standard methods (the Friedewald formula for LDL-C and an automated homogeneous HDL-C assay). The proposed IR method was then developed with a partial least-squares (PLS) regression analysis to quantitatively correlate IR spectral features with the clinical analytical results for 60 randomly chosen specimens. The resulting quantification methods were then validated with the remaining 30 specimens. The PLS model for LDL-C used two spectral ranges (1700–1800 and 2800–3000 cm−1) and eight PLS factors, whereas the PLS model for HDL-C used three spectral ranges (800–1500, 1700–1800, and 2800–3500 cm−1) with six factors. Results: For the 60 specimens used to train the IR-based method, the SE between IR-predicted values and the clinical laboratory assays was 0.22 mmol/L for LDL-C and 0.15 mmol/L for HDL-C (r = 0.98 for LDL-C; r = 0.91 for HDL-C). The corresponding SEs for the test spectra were 0.34 mmol/L (r = 0.96) and 0.26 mmol/L (r = 0.82) for LDL-C and HDL-C, respectively. The precision for the IR-based assays was estimated by the SD of duplicate measurements to be 0.11 mmol/L (LDL-C) and 0.09 mmol/L (HDL-C). Conclusions: IR spectroscopy has the potential to become the clinical method of choice for quick and simultaneous determinations of LDL-C and HDL-C.

Biological Conjugate between Antibody and ZnS Nanoparticles as Probe for Atomic Absorption Spectrophotometry Determination of Estriol

2014 ◽  
Vol 556-562 ◽  
pp. 64-66
Author(s):  
Chun Yan Zhang ◽  
Chuan Tao Wang ◽  
Shu Hao Wang ◽  
Ling Yun Du
Keyword(s):  
Atomic Absorption ◽  
Limit Of Detection ◽  
Water Solution ◽  
Semiconductor Nanocrystals ◽  
Atomic Absorption Spectrophotometry ◽  
Serum Samples ◽  
Absorption Spectrophotometry ◽  
Primary Materials ◽  
Good Agreement

ZnS semiconductor nanocrystals (NCs) were prepared by ways from primary materials of ZnCl2 and Na2S in water solution. Using the synthesized ZnS NCs, a polyclonal antibody-based ZnS-labelled immunosorbent assay for the determination of estriol (E3) was developed with atomic absorption spectrophotometry (AAS) as a detector. An immunoaffinity column was applied to testify conjugation between antibody and ZnS NCs. The linear range for determination of estriol is 40.0~600.0 ng.mL-1, and the limit of detection (LOD) is 10.0 ng.mL-1. Some serum samples have been analyzed with satisfactory results which are in good agreement with those obtained using ELISA. This work suggests the potential application of NCs as biological probes and AAS as detector in nonisotopic immunoassay.

Improvements in and clinical utility of a continuous-flow method for routine measurement of dialyzable (ultrafiltrable) calcium.

1979 ◽  
Vol 25 (11) ◽  
pp. 1939-1943 ◽  
Author(s):  
J Toffaletti ◽  
G N Bowers
Keyword(s):  
Continuous Flow ◽  
Clinical Utility ◽  
Clinical Laboratory ◽  
Serum Samples ◽  
The Past ◽  
Baseline Noise ◽  
Routine Service ◽  
Routine Measurement ◽  
Routine Clinical Laboratory ◽  
Continuous Flow Method

Abstract We describe modifications to the original continuous-flow procedure for dialyzable calcium (Clin. Chem. 23: 1258, 1977) needed to make the method more suitable for routine clinical laboratory use. The modifications simplify the continuous-flow (AutoAnalyzer) manifold, decrease baseline noise, increase the sensitivity, and permit use of a less-expensive fluorometer. Bias due to variation in serum processing is minimized by use of serum samples minimally exposed to air and a pH 7.40 buffer in place of the routinely processed sera and pH 7.30 buffer used formerly. Day-to-day precision (CV) during the past year for samples that included three different lots of quality-control sera was 2 to 3%. The analysis requires 200 micro L of serum, collected with minor additional precautions. We find that dialyzable calcium can be dependably measured in the routine service laboratory and show how this information is clinically more useful than is information on total calcium in serum.

scholarly journals Comparison of Three Skin Sampling Methods and Two Media for Culturing Malassezia Yeast

2020 ◽  
Vol 6 (4) ◽  
pp. 350
Author(s):  
Abdourahim Abdillah ◽  
Saber Khelaifia ◽  
Didier Raoult ◽  
Fadi Bittar ◽  
Stéphane Ranque
Keyword(s):  
Human Skin ◽  
Sampling Methods ◽  
Clinical Laboratory ◽  
Culture Media ◽  
Positive Culture ◽  
Laboratory Procedure ◽  
Study Results ◽  
Malassezia Spp ◽  
Routine Clinical Laboratory ◽  
Sterile Gauze

Malassezia is a lipid-dependent commensal yeast of the human skin. The different culture media and skin sampling methods used to grow these fastidious yeasts are a source of heterogeneity in culture-based epidemiological study results. This study aimed to compare the performances of three methods of skin sampling, and two culture media for the detection of Malassezia yeasts by culture from the human skin. Three skin sampling methods, namely sterile gauze, dry swab, and TranswabTM with transport medium, were applied on 10 healthy volunteers at 5 distinct body sites. Each sample was further inoculated onto either the novel FastFung medium or the reference Dixon agar for the detection of Malassezia spp. by culture. At least one colony of Malassezia spp. grew on 93/300 (31%) of the cultures, corresponding to 150 samplings. The positive culture rate was 67%, 18%, and 15% (P < 10−3), for samples collected with sterile gauze, TranswabTM, and dry swab, respectively. The positive culture rate was 62% and 38% (P < 0.003) by using the FastFung and the Dixon media, respectively. Our results showed that sterile gauze rubbing skin sampling followed by inoculation on FastFung medium should be implemented in the routine clinical laboratory procedure for Malassezia spp. cultivation.

Do we measure bilirubin correctly anno 2005?

2005 ◽  
Vol 43 (5) ◽  
Author(s):  
Joke J. Apperloo ◽  
Fedde van der Graaf ◽  
Volkher Scharnhorst ◽  
Huib L. Vader
Keyword(s):  
Reference Material ◽  
Human Serum ◽  
Reference Materials ◽  
Standard Reference Material ◽  
Total Bilirubin ◽  
Reference Method ◽  
Serum Samples ◽  
Suitable Material ◽  
Good Agreement

AbstractWe observed 30% discrepancy between liquid chemistry and dry chemistry analysers for the determination of total bilirubin in human adult serum samples, which were consistent with a 20% overestimation and 10% underestimation relative to a Jendrassik-Grof reference method, respectively. In contrast, standard reference material SRM916, which was recently recommended as being the most suitable material for attaining interlaboratory agreement, shows very good agreement on both types of analysers, as well as close to 100% recovery with respect to the reference method. We show that the liquid vs. dry bilirubin discrepancies seem to originate in the presence of either conjugated or δ-bilirubin. Our observations make it clear that good interlaboratory (or inter-analyser) agreement between bilirubin reference materials does not guarantee the same for bilirubin concentrations in human serum samples.

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