Improvement of reaction rate measurement precision using the temporally optimized fixed-time ratemeter

1988 ◽  
Vol 60 (6) ◽  
pp. 545-548 ◽  
Author(s):  
Steven A. Engh ◽  
F. James. Holler
Keyword(s):  
Reaction Rate ◽  
Fixed Time ◽  
Measurement Precision ◽  
Rate Measurement

Unimolecular Reaction Rate Measurement of syn-CH3CHOO

2019 ◽  
Vol 10 (17) ◽  
pp. 4817-4821 ◽  
Author(s):  
Xiaohu Zhou ◽  
Yiqiang Liu ◽  
Wenrui Dong ◽  
Xueming Yang
Keyword(s):  
Reaction Rate ◽  
Unimolecular Reaction ◽  
Rate Measurement

Making Enzymatic Methods Optimum for Measuring Compounds with a Kinetic Analyzer

1975 ◽  
Vol 21 (9) ◽  
pp. 1263-1269 ◽  
Author(s):  
John G Atwood ◽  
Joseph L DiCesare
Keyword(s):  
Lactate Dehydrogenase ◽  
Time Constant ◽  
Substrate Concentration ◽  
Reaction Rate ◽  
Molar Absorptivity ◽  
Rate Measurement ◽  
Exponential Time ◽  
Sample Concentration ◽  
Measured Activity ◽  
Enzymatic Methods

Abstract Kinetic enzymatic methods for analysis of substrates can be made optimum for a sensitive photometric analyzer by adjusting the activity of the triggering (catalyzing) enzyme so that the reaction rate is maximum at the time of measurement. At this optimum activity, the exponential time constant for exhaustion of substrate equals the time between triggering and rate measurement. The scale factor (defined as measured activity divided by sample concentration in the reaction mixture) is the same for all tests. Sensitivity to substrate concentration is predictable from instrumental absorbance uncertainty and molar absorptivity of the absorbing species. These predictions from Michaelis theory were verified experimentally for pyruvate and lactate triggered with lactate dehydrogenase, for glucose triggered with hexokinase, and for triglycerides triggered with glycerol kinase, the reaction rate being measured 30 s after triggering. Sensitivities of 1.5 x 10-7 mol/ liter were achieved. Serum diluted 1000-fold and analyzed for glucose gave a repeatability of 25 mg/liter with linearity to 4.0 g/liter. Samples diluted 300-fold and analyzed for triglycerides gave 30 mg/liter repeatability, with linearity to concentrations exceeding 3.0 g/liter.

Minimization of errors in fixed-time reaction rate methods by optimization of measurement time

1982 ◽  
Vol 54 (4) ◽  
pp. 755-761 ◽  
Author(s):  
F. J. Holler ◽  
R. K. Calhoun ◽  
S. F. McClanahan
Keyword(s):  
Reaction Rate ◽  
Fixed Time ◽  
Measurement Time ◽  
Minimization Of Errors

Fixed-time kinetic assay of plasma ammonia, with NADPH as cofactor, with a centrifugal analyzer.

1979 ◽  
Vol 25 (4) ◽  
pp. 611-613 ◽  
Author(s):  
P K Li ◽  
B C Shull
Keyword(s):  
Reaction Rate ◽  
Enzymatic Reaction ◽  
Fixed Time ◽  
Kinetic Assay ◽  
Plasma Ammonia ◽  
Standard Curve ◽  
Analytical Recovery ◽  
Silver Spring ◽  
Catalytic Amination ◽  
Preincubation Time

Abstract We describe a fixed-time, enzymatic, reaction-rate procedure for determining plasma ammonia with a centrifugal analyzer (Rotochem IIA/36; American Instrument Co., silver Spring, MD 20910), with NADPH as cofactor. The reaction is based on that of da Fonseca-Wollheim's modification [J. Clin. Chem. Clin. Biochem. 11, 421 (1973)] of the Kirstein reaction, which depends on the catalytic amination of alpha-ketoglutarate by the action of glutamate dehydrogenase with NADPH as the cofactor instead of NADH. Use of NADPH minimizes interference from endogenous reactions such as that between lactate dehydrogenase and pyruvate. This method permits shortened preincubation time and thus improves both specificity and precision. This assay requires 100 microliter of freshly collected heparinized plasma, gives quantitative analytical recovery, and the standard curve is linear to 430 mumol/L. Data are presented comparing results with those by two other enzymatic ammonia procedures.

Reaction Rate Measurement of Multiple Enzyme Samples by Continuous Flow Analysis

1967 ◽  
Vol 13 (10) ◽  
pp. 847-854 ◽  
Author(s):  
Harold H Brown ◽  
Mary R Ebner
Keyword(s):  
Alkaline Phosphatase ◽  
Light Absorption ◽  
Continuous Flow ◽  
Reaction Rate ◽  
Single Point ◽  
Flow Analysis ◽  
Enzyme Assays ◽  
Rate Measurement ◽  
Kinetic Assay ◽  
Continuous Flow Analysis

Abstract A simple technic to adapt the advantages of continuous flow analysis to the kinetic assay of multiple enzyme samples is described. It will permit adequate standardization by primary or secondary standards run through the entire analysis of those procedures that do not exhibit spontaneous changes in light absorption or fluorescence with time. The adaptation of the Kind-King method for alkaline phosphatase (1) to this technic is given to demonstrate the superiority of such a system over single-point enzyme assays.

Kinetic approach for the enzymic determination of creatinine.

1984 ◽  
Vol 30 (11) ◽  
pp. 1792-1796 ◽  
Author(s):  
N Perakis ◽  
C M Wolff
Keyword(s):  
Creatine Kinase ◽  
Limit Of Detection ◽  
Enzyme System ◽  
Fixed Time ◽  
Rate Measurement ◽  
Single Measurement ◽  
Serum Samples ◽  
Reaction Method ◽  
Kinetics Of

Abstract By exploiting the kinetics of NADH consumption in the enzyme system creatinine amidohydrolase + creatine kinase + pyruvate kinase + lactate dehydrogenase, one can determine creatinine in serum in the range of 1 to 90 mg/L. By using the conditions defined here, this determination can be made with a single measurement of the rate of disappearance of NADH. The analytical rate measurement is made at a fixed time (2 min) after the sample is introduced into the enzyme solution. For this fixed time, the interferences of creatine and pyruvate are eliminated. Results so obtained for creatinine in human blood serum samples correlated well (r = 0.98) with those obtained by the classical Jaffé-reaction method. Run-to-run reproducibility (CV) was 3%, and the limit of detection was 1 mg/L.

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