Automated enzymatic determination of L-lactate in serum, with use of a miniature centrifugal analyzer.

1976 ◽  
Vol 22 (12) ◽  
pp. 2042-2045 ◽  
Author(s):  
T P Hadjiioannou ◽  
S I Hadjiioannou ◽  
S D Brunk ◽  
H V Malmstadt
Keyword(s):  
Lactate Dehydrogenase ◽  
Reaction Rate ◽  
Enzymatic Reaction ◽  
Reaction Rates ◽  
Enzymatic Determination ◽  
Analytical Recovery ◽  
Rate Method ◽  
Relative Errors ◽  
Lithium Lactate

Abstract We describe an automated enzymatic reaction-rate method for spectrophotometric determination of lactate in serum with a miniature centrifugal analyzer. The L(+) -lactate is selectively oxidized in the presence of lactate dehydrogenase (EC 1.1.1.27) and NAD+ to form NADH, which is measured from its absorption. Reaction rates are determined automatically, and unknown concentrations are calculated from a computer-generated calibration curve with aqueous lithium lactate standards. Lactate concentrations in the range 0.32-1.6 mug/4 mul (80-400 mg/liter) of sample were determined with relative errors and coefficient of variation of 4.8%. Analytical recovery of lactate added to pooled serum was 89-112% (average, 101%). Comparison with a kit ("Rapid Lactate") method gave a correlation coefficient squared of 0.979 over a concentration range of 39-779 mg/liter.

Automated Enzymatic Determination of L-Lactate in Serum, with Use of a Miniature Centrifugal Anlyzer

1976 ◽  
Vol 22 (12) ◽  
pp. 2038-2041 ◽  
Author(s):  
T P Hadjiioannou ◽  
S I Hadjiioannou ◽  
S D Brunk ◽  
H V Malmstadt
Keyword(s):  
Lactate Dehydrogenase ◽  
Reaction Rate ◽  
Enzymatic Reaction ◽  
Reaction Rates ◽  
Enzymatic Determination ◽  
Analytical Recovery ◽  
Rate Method ◽  
Relative Errors ◽  
Lithium Lactate

Abstract We describe an automated enzymatic reaction-rate method for spectrophotometric determination of lactate in serum with a miniature centrifugal analyzer. The L(+)-lactate is selectively oxidized in the presence of lactate dehydrogenase (EC 1.1.1.27) and NAD+ to from NADH, whitch is measured from its absorption. Reaction rates are determined automatically, and unknown concentrations are calculated from a computer0generated calibration curve with aqueous lithium lactate standards. Lactte concentrations in the range 0.32-1.6 µg/4 µl (80-400 mg/liter) of sample were determined with relative errors and coefficient of variation of 4.8%. Analytical recovery of lactate added to pooled serum was 89-112% (average, 101%). Comparison with a kit ("Rapid Lactate") method gave a correlation coefficient squared of 0.979 over a concentration range of 39-779 mg/liter.

Specific Enzymatic Determination of Glucose in Blood Serum or Plasma by an Automatic Potentiometric Reaction-Rate Method

1962 ◽  
Vol 8 (6) ◽  
pp. 606-615 ◽  
Author(s):  
H V Malmstadt ◽  
H L Pardue
Keyword(s):  
Blood Serum ◽  
Blood Plasma ◽  
Reaction Rate ◽  
Measurement Time ◽  
Sample Handling ◽  
Enzymatic Determination ◽  
Speed Up ◽  
Rate Method ◽  
Relative Errors

Abstract A new automatic potentiometric reaction-rate method has been applied to the specific enzymatic measurement of glucose in blood plasma or serum. A new filtering technic is described for removal of precipitated protein. The use of injection pipets to simplify and speed up the reagent-and sample-handling step is described. Glucose is determined in 0.02 ml. of serum or plasma with relative errors within 2%. The average measurement time is about 30 sec.

Automated enzymic determination of ethanol in blood, serum, and urine with a miniature centrifugal analyzer.

1976 ◽  
Vol 22 (6) ◽  
pp. 802-805 ◽  
Author(s):  
T P Hadjiioannou ◽  
S I Hadjiioannou ◽  
J Avery ◽  
H V Malmstadt
Keyword(s):  
Blood Serum ◽  
Reaction Rates ◽  
Rate Of Change ◽  
Coefficients Of Variation ◽  
Analytical Recovery ◽  
Rate Method ◽  
Relative Errors ◽  
Urine Specimens ◽  
Serum And Urine

Abstract We describe an automated spectrophotometric reaction-rate method for determination of ethanol in serum and urine with a miniature centrifugal analyzer. The theanol is selectively oxidized in the presence of alcochol dehydrogenase and NAD+ to form NADH, which is measured by the rate of change of its absorbance. Reaction rates are determined automatically, and unknown concentrations are calculated from a computer-generated working curve based on aqueous ethanol standards. Blood, serum, or urine specimens need not be deproteinized. The method permits duplicate analysis of at least 30 samples per hour. Coefficients of variation and relative errors are about 2-3% for ethanol concentrations of 0.3-3.0 mug per 2 mul of sample. Analytical recovery of ethanol added to serum is 92-103% (average, 98.5%). Comparisons with distillation-oxidation, gas-chromatographic, and conventional enzymic procedures give satisfactory agreement.

Automatic Determination of Lactic Acid in Blood

1969 ◽  
Vol 15 (10) ◽  
pp. 940-948 ◽  
Author(s):  
T P Hadjiioannou ◽  
P A Siskos ◽  
C G Valkana
Keyword(s):  
Lactic Acid ◽  
Reaction Rate ◽  
Lactic Dehydrogenase ◽  
Lactic Acid Concentration ◽  
Automatic Determination ◽  
Fixed Amount ◽  
Rate Method ◽  
Relative Errors ◽  
Time Required

Abstract An automatic reaction rate method is described for the determination of lactic acid in blood. The L(+)-lactic acid is selectively oxidized in the presence of lactic dehydrogenase and diphosphopyridine nucleotide to form an absorbing species. The time required for the formation of a fixed amount of DANH is measured automatically and related directly to the lactic acid concentration. The method is sensitive, more rapid than purely chemical procedures, and relative errors are only about 1-3% for the range 6-200 µg of lactic acid. The coefficient of variation for the determination of lactic acid in 0.2 ml of blood is 3%. Measurement times vary from a few seconds to about 2 min.

Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.

1983 ◽  
Vol 29 (8) ◽  
pp. 1513-1517 ◽  
Author(s):  
M W McGowan ◽  
J D Artiss ◽  
B Zak
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Amniotic Fluid ◽  
Enzymatic Reaction ◽  
Detergent Solution ◽  
Enzymatic Determination ◽  
Red Color ◽  
Hydrolysis Of ◽  
Zwitterionic Detergent

Abstract A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.

Rapid enzymatic determination of urinary oxalate.

1989 ◽  
Vol 35 (12) ◽  
pp. 2330-2333 ◽  
Author(s):  
M G Li ◽  
M M Madappally
Keyword(s):  
Enzyme Assay ◽  
Divalent Cations ◽  
Urinary Oxalate ◽  
Assay Sensitivity ◽  
Color Development ◽  
Assay Procedure ◽  
Enzymatic Determination ◽  
Analytical Recovery ◽  
Urine Specimens

Abstract This new reagent kit for the quantitative measurement of oxalate in urine is a modification of an earlier Sigma oxalate assay procedure (procedure no. 590), a coupled enzyme assay involving oxalate oxidase and horseradish peroxidase. The new analytical procedure includes methods for processing urine specimens to eliminate interference with oxalate color development at 590 nm by ascorbic acid, divalent cations, and other urinary constituents. The reaction is complete in less than 5 min, and results are linearly related to oxalate concentration up to at least 1 mmol/L. Assay sensitivity and within-run and between-run precision were within the limits acceptable for other urinary oxalate procedures. Analytical recovery of added oxalate was close to 100%. This specific, simple, rapid procedure is suitable for routine clinical use.

Reaction-rate method for the determination of phosphorus in agricultural products

Talanta ◽  
1979 ◽  
Vol 26 (6) ◽  
pp. 467-471 ◽  
Author(s):  
M.S. McCracken ◽  
H.V. Malmstadt®
Keyword(s):  
Reaction Rate ◽  
Agricultural Products ◽  
Rate Method
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