A stopped-flow clinical analyzer in which immobilized-enzyme reaction loops are used.

1977 ◽  
Vol 23 (6) ◽  
pp. 1033-1036 ◽  
Author(s):  
M D Joseph ◽  
D J Kasprzak ◽  
S R Crouch
Keyword(s):  
Immobilized Enzyme ◽  
Enzymatic Reaction ◽  
Enzyme Reaction ◽  
Fixed Time ◽  
Stopped Flow ◽  
Good Precision ◽  
Indicator Reaction ◽  
Flow Mixing ◽  
Kinetic Mode

Abstract A stopped-flow clinical analyzer is described that makes use of a reaction loop containing immobilized enzyme(s) for the determination of the analyte/substrate. The analyzer has been evaluated by determining glucose with immobilized glucose oxidase. The stopped-flow mixing system was constructed at a current cost of less than $500. The analyzer separates the enzymatic reaction from a followup, spectrophotometric indicator reaction. This separation allows the enzymatic reaction to be used in either a fixed-time, kinetic mode or in an equilibrium mode. Likewise, the indicator reaction can be used in either mode. Results for glucose in blood serum indicate that good precision and accuracy can be obtained.

Chemiluminescence Determination of Glucose, Fructose and their Mixture by the Stopped-Flow Mixing Technique

2003 ◽  
Vol 141 (1-2) ◽  
pp. 73-78 ◽  
Author(s):  
Tomás Pérez-Ruiz ◽  
Carmen Martínez-Lozano ◽  
Virginia Tomás ◽  
José Fenoll
Keyword(s):  
Stopped Flow ◽  
Flow Mixing

Simultaneous kinetic-photometric determination of imipramine and desipramine by stopped-flow mixing technique

1993 ◽  
Vol 283 (1) ◽  
pp. 471-475 ◽  
Author(s):  
Lourdes de la Peña ◽  
Agustina Gómez-Hens ◽  
Dolores Pérez-Bendito
Keyword(s):  
Photometric Determination ◽  
Stopped Flow ◽  
Flow Mixing

Kinetic study of the Jaffé reaction for quantifying creatinine in serum: 2. Evaluation of buffered reagent and comparison of different data-processing options.

1989 ◽  
Vol 35 (3) ◽  
pp. 360-363 ◽  
Author(s):  
B L Bacon ◽  
H L Pardue
Keyword(s):  
Data Processing ◽  
Curve Fitting ◽  
Fixed Time ◽  
Good Precision ◽  
Creatinine Concentration ◽  
Kinetic Determination ◽  
Predictive Method ◽  
Target Values ◽  
Standard Additions

Abstract Here we describe the evaluation of several data-processing options for the kinetic determination of creatinine by use of the Jaffé reaction. Data-processing options evaluated include initial-rate, two-point fixed-time, rate at t = k-1, and multipoint curve-fitting predictive methods. We evaluated these options for a buffered formulation of the Jaffé reagent and studied the effects of potential interferents, including glucose, acetoacetate, bilirubin, and albumin, on each option. To reduce effects of bilirubin, we evaluated the inclusion of a preoxidation step with ferricyanide. All the data-processing options gave good precision and linearity between the measurement objective and creatinine concentration. However, differences between slopes of calibration plots in aqueous and serum matrices ranged from a high of +60% for the two-point, fixed-time method to a low of -11% for the curve-fitting, predictive method. Standard additions of creatinine to sera were quantified reliably (yielding 96% to 102% of target values) by the predictive method and less reliably (62% to 102%) by the other methods. We conclude that the predictive method has the potential to yield the most reliable results for creatinine.

Optimized Determination of γ-Glutamyltransferase by Reaction-Rate Analysis

1974 ◽  
Vol 20 (9) ◽  
pp. 1121-1124 ◽  
Author(s):  
Sidney B Rosalki ◽  
David Tarlow
Keyword(s):  
Dilute Hydrochloric Acid ◽  
Reaction Rate ◽  
Enzymatic Reaction ◽  
Enzyme Reaction ◽  
Enzyme Reactions ◽  
Rate Analysis ◽  
Acid Substrate ◽  
Incubation Buffer ◽  
Optimal Ph

Abstract We describe a method for measuring γ-glutamyltransferase (EC 2.3.2.2) activity in serum, which can be used with automated enzyme analyzers (such as the LKB 8600 Reaction Rate Analyzer) that require enzyme reactions to be initiated with substrate. The method also permits optimal determination conditions to be obtained at 37 °C. The enzymatic reaction is commenced by adding γ-glutamyl-p-nitroanilide dissolved in dilute hydrochloric acid to samples pre-incubated with tris(hydroxymethyl)aminomethane—glycylglycine buffer. The p-nitroaniline liberated is continously monitored at 37 °C at 405 nm. The pH of the pre-incubation buffer is such that the optimal pH for the enzyme reaction results from addition of the acid substrate solution.

Combined enzymic-Jaffé method for determination of creatinine in serum.

1981 ◽  
Vol 27 (1) ◽  
pp. 18-21 ◽  
Author(s):  
P Masson ◽  
P Ohlsson ◽  
I Björkhem
Keyword(s):  
Reference Method ◽  
Enzyme Reaction ◽  
Creatine Phosphate ◽  
Mass Fragmentography ◽  
Good Precision ◽  
Serum Samples ◽  
Modified Method ◽  
Combined Use ◽  
High Concentrations

Abstract Concentrations of creatinine, as determined in serum by a method involving the combined use of creatinine amidohydrolase (EC 3.5.2.10) and alkaline sodium picrate were found to be factitiously low, owing to a reversal of the enzyme reaction. This effect could be eliminated by converting creatine, the product of the enzymic reaction, to creatine phosphate. The combined enzymic-Jaffé method was therefore modified to include creatine amidohydrolase, creatine kinase, ATP, and Mg2+ in the reaction mixture. The modified method has good precision. We saw no significant interferences by relatively high concentrations of acetone, acetylacetone, ADP, creatine, creatine phosphate, glucose, glycocyamine, or pyruvate. Likewise, no interferences were evident with icteric, lipemic, or hemolytic serum samples. There was an excellent agreement between creatinine values obtained with our method and by a reference method based on isotope dilution-mass fragmentography. Our method is considerably simpler than the fully enzymic method for determination of creatinine and might be a method of choice if a high accuracy is desired.

Fluorimetric determination of total ascorbic acid by a stopped-flow mixing technique

The Analyst ◽  
2001 ◽  
Vol 126 (8) ◽  
pp. 1436-1439 ◽  
Author(s):  
Tomás Pérez-Ruiz ◽  
Carmen Martínez-Lozano ◽  
Virginia Tomás ◽  
José Fenol
Keyword(s):  
Ascorbic Acid ◽  
Stopped Flow ◽  
Fluorimetric Determination ◽  
Flow Mixing
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