Kinetic Enzymatic Method for Determining Serum Creatinine

1975 ◽  
Vol 21 (10) ◽  
pp. 1422-1426 ◽  
Author(s):  
Gerald A Moss ◽  
Richard J L Bondar ◽  
Diane M Buzzelli
Keyword(s):  
Serum Creatinine ◽  
Accurate Determination ◽  
Test Subject ◽  
Rate Of Change ◽  
Enzymatic Method ◽  
Inhibitory Effects ◽  
Standard Curve ◽  
Analytical Recovery ◽  
Enzymatic Procedure

Abstract Creatinine amidohydrolase is used to measure serum creatinine in a totally enzymatic procedure. Creatine, produced by hydrolysis, is acted upon by creatine kinase, and then by pyruvate kinase and lactate dehydrogenase, to result in a change in absorbance at 340 nm. The amount of creatinine present is related to the rate of change in A340 and is determined from a standard curve. Absorbance and concentration are linearly related to 100 mg/liter and only 250 µl of serum is required. At 1.0 g/liter, heparin, oxalate, citrate, ethylenediaminetetraacetate, ascorbate, or glucose had no significant effect on the accurate determination of creatinine; higher concentrations (30 g/liter) had inhibitory effects on the test. Analytical recovery of creatinine added to either normal or abnormal sera averaged 102%. When results of this procedure and of the standard direct Jaffé test were compared, the latter were significantly higher. Unlike the Jaffé method, the present method of determining creatinine is rapid (about 10 min per test), subject to few or no interfering substances, and requires no serum deproteinization.

Evaluation of a modified alcohol dehydrogenase assay for the determination of ethanol in blood.

1982 ◽  
Vol 28 (10) ◽  
pp. 2125-2127 ◽  
Author(s):  
A Poklis ◽  
M A Mackell
Keyword(s):  
Gas Chromatography ◽  
Reaction Time ◽  
Alcohol Dehydrogenase ◽  
Correlation Coefficients ◽  
Least Square ◽  
Standard Curve ◽  
Analytical Recovery ◽  
Sigma Chemical ◽  
Enzymic Assay

Abstract We evaluated a new alcohol dehydrogenase (EC 1.1.1.1) enzymic assay (ADH-glycine, Sigma Chemical Co.) for the determination of ethanol in blood. This assay differs from the manufacturer's previous assay (ADH-pyrophosphate) in that glycine replaces pyrophosphate as the buffer and hydrazine replaces semicarbazide as the trapping agent. The standard curve for the assay was linear over blood ethanol concentrations of 0.50-5.00 g/L. The reaction time of the assay was 10 min. At 1.00 g/L within-run and between-run CVs were 3.96% (n = 20) and 4.01% (n = 20), respectively. Mean analytical recovery of ethanol added to whole blood at 0.50-5.00 g/L was 99.7% (SD 2.6%). We performed 100 consecutive clinical and forensic determinations by the ADH-glycine assay, the ADH-pyrophosphate assay, and gas chromatography. Correlation coefficients of the results by least-square linear regression were 0.995 for ADH-pyrophosphate vs ADH-glycine, and 0.990 for gas chromatography vs ADH-glycine. The major advantage of the ADH-glycine assay over the ADH-pyrophosphate assay is the shorter reaction time, 10 min vs 30 min.

Use of a competitive inhibitor in a kinetic enzymatic method for measuring ethanol in serum.

1987 ◽  
Vol 33 (12) ◽  
pp. 2296-2298 ◽  
Author(s):  
E Young ◽  
B Rafter-Tadgell
Keyword(s):  
Regression Analysis ◽  
Reaction Time ◽  
Alcohol Dehydrogenase ◽  
Linear Regression Analysis ◽  
Competitive Inhibitor ◽  
Enzymatic Method ◽  
Standard Curve ◽  
Analytical Recovery ◽  
Liquid Chromatographic ◽  
Total Reaction Time

Abstract We describe a kinetic enzymatic method for ethanol in serum, based on the use of pyrazole, a competitive inhibitor for alcohol dehydrogenase (EC 1.1.1.1). The method is rapid and is easily automated for the Cobas Bio centrifugal analyzer. No specimen pretreatment is necessary and the total reaction time is 120 s. The standard curve is linear up to 140 mmol/L. The within-run CV was between 1.9% and 3.5%; the between-run CV ranged from 2.6% to 4.1%. Mean analytical recovery of ethanol added to serum was 100.2%. We compared results of the kinetic enzymatic method with those from a gas-liquid chromatographic (GLC) method and another commercial alcohol dehydrogenase method (TDx REA Ethanol; Abbott Diagnostics). Linear regression analysis gave the following equations: kinetic = 0.991GLC - 0.354 mmol/L (r = 0.992, n = 110) and kinetic = 0.998TDx - 1.741 mmol/L (r = 0.993, n = 70). No interference from methanol or isopropanol was seen.

Liquid-chromatographic determination of acetaminophen in serum.

1979 ◽  
Vol 25 (3) ◽  
pp. 409-412 ◽  
Author(s):  
C G Fletterick ◽  
T H Grove ◽  
D C Hohnadel
Keyword(s):  
Chromatographic Determination ◽  
Pharmacokinetic Studies ◽  
Structural Isomers ◽  
Internal Standards ◽  
Standard Curve ◽  
Liquid Chromatographic Method ◽  
Analytical Recovery ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a sensitive and precise "high-pressure" liquid-chromatographic method for determining acetaminophen in serum. The 2-acetaminophenol and 3-acetaminophenol structural isomers of acetaminophen are used as internal standards. The method, which involves solvent extraction and adsorption chromatography on silica, provides excellent sensitivity, accuracy, and selectivity. The standard curve is linear over the range of acetaminophen concentrations of 0.5 to 300 mg/L, which makes the method useful for both pharmacokinetic studies and overdose monitoring. Analytical recovery is 97% for acetaminophen concentrations ranging from 5 to 300 mg/L. Many commonly used drugs were tested and found not to interfere. The procedure has been successfully adapted as a microscale method requiring only 50 microL of sample. The microscale method is particularly useful for pediatric and neonatal patients for whom sample size is a major concern.

Optimal Conditions for the Enzymatic Determination of L-Lactic Acid

1962 ◽  
Vol 8 (1) ◽  
pp. 1-10 ◽  
Author(s):  
G F Olson
Keyword(s):  
Lactic Acid ◽  
Heart Muscle ◽  
Lactic Dehydrogenase ◽  
Test System ◽  
Optimal Conditions ◽  
Enzymatic Method ◽  
Chemical Methods ◽  
Enzymatic Determination ◽  
Enzymatic Procedure

Abstract A simple enzymatic method for the determination of lactic acid with muscle lactic dehydrogenase is described. L(+) Lactate in amounts from 0.04 µM to 0.4 µM can be directly measured by following the formation of reduced diphosphopyridine nucleotide at 340 mµ. The effect of varying the concentrations of reactants in the test system was studied, and the optimal concentrations for stoichiometric conversion of lactate to pyruvate were determined. When lactic acid concentrations in plasma, liver, and heart muscle were determined by both enzymatic and chemical methods, identical results were obtained. The advantages of the present enzymatic procedure over chemical methods are discussed.

Microencapsulated antibodies in radioimmunoassay--I. Determination of digoxin.

1979 ◽  
Vol 25 (6) ◽  
pp. 860-862 ◽  
Author(s):  
E P Halpern ◽  
R W Bordens
Keyword(s):  
Interfacial Polymerization ◽  
Clinical Laboratory ◽  
Rabbit Antibody ◽  
Nylon Membrane ◽  
Antibody Technique ◽  
Standard Curve ◽  
Analytical Recovery ◽  
Routine Clinical Laboratory ◽  
Toxic Concentrations

Abstract We describe the application of the microencapsulated-antibody technique to the radioimmunoassay of digoxin in serum. Droplets of emulsified rabbit antibody are microencapsulated in a semipermeable nylon membrane by an interfacial polymerization technique. The antibody microcapsules are incubated with 125I-labeled digoxin and unlabeled digoxin for 15 min at 37 degrees C, then free and bound digoxin are separated by centrifugation. Subtherapeutic, therapeutic, and toxic concentrations of digoxin in sera can be determined, with use of a standard curve prepared by use of known amounts of digoxin. With this technique we obtained an intra-laboratory correlation coefficient of 0.945 for 100 patients' sera and one of 0.940 for interlaboratory results for 21 sera (10 laboratories) when compared to a routine clinical laboratory radioimmunoassay for digoxin. Icterus, lipemia, hemoglobin, or disproteinemia had no effect on the analytical recovery of digoxin. The standard curve was linear to 6 microgram/L; the sensitivity was 0.25 microgram/L.

Evaluation of an Enzymatic Procedure for Determination of Serum Cholesterol with the Abbott ABA-100

1974 ◽  
Vol 20 (10) ◽  
pp. 1282-1286 ◽  
Author(s):  
David L Witte ◽  
David A Barrett II ◽  
Delane A Wycoff
Keyword(s):  
Clinical Laboratory ◽  
Normal Subjects ◽  
Lipid Research Clinic ◽  
Negative Bias ◽  
Enzymatic Method ◽  
Regression Slope ◽  
Steroid Drugs ◽  
Enzymatic Procedure ◽  
Positive Interference

Abstract A previously reported direct enzymatic method for cholesterol [ Clin. Chem. 20, 470 (1974)] was critically evaluated in the clinical laboratory. Other methods compared to this enzymatic procedure were: (a) the manual Abell—Kendall procedure, giving a regression slope (proportional sensitivity) of 0.998 and a negative bias of 9.7 mg/dl in the enzymatic procedure; (b) Lipid Research Clinic procedure, giving a regression slope of 1.005 and a negative bias of 8.8 mg/dl in the enzymatic procedure; and (c) the SMA 12/60 (Technicon) method, giving a regression slope of 0.881 and a negative bias of 20.8 in the enzymatic procedure. Replicate analyses of pooled serum by the enzymatic procedure demonstrated the following inter-run precision: mean = 178 mg/dl, SD = 4 mg/dl, CV = 2.2%. Bilirubin caused a slight positive interference (1 mg of bilirubin per deciliter appears as 1-2 mg of cholesterol). Hemolysis, lipemia, and a series of steroid drugs caused no interference. A group of 465 normal subjects was tested by the enzymatic procedure. This population had a mean cholesterol of 203 mg/dl. The 2.5 percentile was 130 mg/dl, and the 97.5 percentile was 316 mg/dl.

Determination of urinary oxalate with commercially available oxalate oxidase.

1983 ◽  
Vol 29 (4) ◽  
pp. 700-702 ◽  
Author(s):  
J E Buttery ◽  
N Ludvigsen ◽  
E A Braiotta ◽  
P R Pannall
Keyword(s):  
Chemical Method ◽  
Oxalate Oxidase ◽  
Regression Equation ◽  
Urinary Oxalate ◽  
Enzymatic Method ◽  
Analytical Recovery ◽  
Wide Range ◽  
Better Than

Abstract For this direct colorimetry of urinary oxalate, commercially available oxalate oxidase (EC 1.2.3.4) is used. The urine is first diluted, to diminish the effect of interfering substances. Analytical recovery of oxalate from urines with five different oxalate concentrations (0.4 to 2.0 mmol/L) ranged from 92 to 109% (mean 99%). The within-day and between-day precision (CV) of the method for a wide range of oxalate concentrations averaged better than 10%. There is good correlation (r = 0.977) between this enzymatic method (y) and the chemical method of Hodgkinson and Williams (x) [Clin Chim Acta 36: 127-132, 1972], the regression equation being y = 1.014x + 0.061. Urines with added ascorbate give falsely increased results. The proposed method is inexpensive and simple to perform.

Microencapsulated antibodies in radioimmunoassay. III. Determination of cortisol.

1980 ◽  
Vol 26 (5) ◽  
pp. 633-634 ◽  
Author(s):  
R W Bordens ◽  
E P Halpern
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Plasma Cortisol ◽  
Total Plasma ◽  
Competitive Reaction ◽  
Large Molecules ◽  
Standard Curve ◽  
Analytical Recovery

Abstract We describe a method for directly measuring total plasma cortisol by use of a microencapsulated antibody. The antibody microcapsules were incubated with plasma and 125I-labeled cortisol in a competitive reaction at 37 degrees C for 15 min, then separated by centrifugation; the radioactivity of the pellet was counted for 1 min. Analytical recovery of cortisol from three plasma pools was 97.6% (SD 8.5%) and was unaffected by triglyceridemia, hemolysis, or icterus. The standard curve was linear to 500 microgram/L and the sensitivity was 10 microgram/l. Recovery of cortisol added as the hemisuccinate was 102% (SD 10.6%), whereas that of the conjugate cortisol hemisuccinate/bovine serum albumin was 4.3% (SD 3.5%). This confirmed that the microcapsule excludes large molecules. The within-day CV for two control pools was 9.8 and 12.8%, the day-to-day variation 13.4 and 13.8%.

Improved determination of aluminum in serum and urine with use of a stabilized temperature platform furnace.

1982 ◽  
Vol 28 (10) ◽  
pp. 2139-2143 ◽  
Author(s):  
F Y Leung ◽  
A R Henderson
Keyword(s):  
Reference Interval ◽  
Matrix Interference ◽  
Linear Calibration ◽  
Standard Curve ◽  
Steady State Temperature ◽  
Analytical Recovery ◽  
Standard Additions ◽  
Assay Precision ◽  
Serum And Urine

Abstract This method for determining aluminum in serum and urine is essentially free from matrix interference and gives a linear response with concentration to at least 500 micrograms/l. Use of a stabilized temperature platform (L'vov platform, Perkin-Elmer Corp.) to approach a "steady-state" temperature, addition of matrix modifiers [especially Mg(NO3)2], and the use of peak area integration all helped substantially diminish spectral interference. With the platform furnace, serum protein concentrations as great as 260 g/L did not interfere with the determination of Al. The within- and between-assay precision (CV) was less than or equal to 3.5% and less than or equal to 7.4%, respectively. Analytical recovery of Al added to serum ranged between 95 and 101% throughout the linear calibration range (to 500 micrograms/L), either when measured directly from the standard curve or by the method of standard additions. The reference interval for Al in 28 healthy subjects was 2-14 micrograms/L (mean 6.5, SD 4.1 micrograms/L), and for 130 patients on hemodialysis, 20-550 micrograms/L (mean 87.5, SD 62.5 micrograms/L).

Electrothermal atomic absorption determination of aluminum in tissues dissolved in tetramethyl ammonium hydroxide.

1984 ◽  
Vol 30 (5) ◽  
pp. 745-747 ◽  
Author(s):  
B J Stevens
Keyword(s):  
Atomic Absorption ◽  
Matrix Effects ◽  
Graphite Furnace ◽  
Accurate Determination ◽  
Ammonium Hydroxide ◽  
Laboratory Rats ◽  
Tetramethyl Ammonium ◽  
Tetramethyl Ammonium Hydroxide ◽  
Analytical Recovery

Abstract In this rapid, precise method for the accurate determination of aluminum in biological tissue, the only preparative step required is the dissolution of the sample in hot aqueous tetramethyl ammonium hydroxide, followed by dilution with ethanol. Aluminum is measured by electrothermal (graphite furnace) atomic absorption spectroscopy, with direct reference to aqueous standards. The CVs for the method within-day and day-to-day are 3.0% and 6.8%, respectively. Analytical recovery of added aluminum is 86 to 108%, and matrix effects are minimal. Measurement of aluminum in tissue from normal laboratory rats and rats injected with aluminum gave values close to those found by an acid digestion method, but higher than those obtained by extraction with a saturated solution of ethylenediaminetetraacetate.

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