Manual and continuous-flow colorimetry of triacylglycerols by a fully enzymic method.

1979 ◽  
Vol 25 (2) ◽  
pp. 273-278 ◽  
Author(s):  
R E Megraw ◽  
D E Dunn ◽  
H G Biggs
Keyword(s):  
Continuous Flow ◽  
Colorimetric Assay ◽  
Tetrazolium Salt ◽  
Good Precision ◽  
Free Glycerol ◽  
Serum Triglycerides ◽  
Precision And Accuracy ◽  
Glycerol 3 Phosphate Dehydrogenase ◽  
Microbial Esterase ◽  
Continuous Flow Method

Abstract We describe a fully enzymic method for manual and continuous-flow colorimetric assay of triacylglycerols (triglycerides) in serum. Triglycerides are enzymically hydrolyzed in 10 min by lipase and microbial esterase. The resulting free glycerol is measured enzymically by glycerol kinase and glycerol-3-phosphate dehydrogenase. The NADH so formed is oxidized by coupling with a tetrazolium salt/diaphorase system. The test follows Beer's law to 8 g/L, and the final color is stable for at least 1 h for serum, 15 min for aqueous triolein standards. The manual assay requires only 25 microliter of serum and few manipulations. A specific triolein standard was developed for calibrating the manual method. For the continuous-flow method, calibration is made with four concentrations of glycerol standard. The procedure is sensitive, has good precision and accuracy, and gives results that compare well with chemical and enzymic commercial kit methods.

Continuous-flow enzymic method evaluated for measurement of serum triglycerides with use of an improved lipase reagent.

1978 ◽  
Vol 24 (11) ◽  
pp. 2018-2019 ◽  
Author(s):  
K Whitlow ◽  
N Gochman
Keyword(s):  
Continuous Flow ◽  
Flow System ◽  
Free Glycerol ◽  
Fluorometric Method ◽  
Serum Triglycerides ◽  
Microbial Lipase ◽  
Flow Method ◽  
Dual Channel ◽  
Continuous Flow Method ◽  
Total Triglyceride

Abstract We compared a modified enzymic continuous-flow method for serum triglycerides, in which a microbial lipase is used without protease, to an extraction-fluorometric method. Results (for total--blank) correlated well with those by the comparison procedure: enzymic = 1.002 fluorometric--14 mg/liter; r = 0.9968. Serum blanks were measured for each sample in both methods, and the concentration of free glycerol measured by the enzymic method was shown to be as much as 15 to 71% of the total triglyceride result in 7% of the samples analyzed. The dual-channel continuous-flow system provides automatic free-glycerol blank subtraction for the enzymic method.

A continuous-flow (AutoAnalyzer II) procedure for measuring erythrocyte transketolase activity.

1982 ◽  
Vol 28 (11) ◽  
pp. 2206-2213 ◽  
Author(s):  
P P Waring ◽  
D Fisher ◽  
J McDonnell ◽  
E L McGown ◽  
H E Sauberlich
Keyword(s):  
Reaction Kinetics ◽  
Continuous Flow ◽  
Good Precision ◽  
Internal Standards ◽  
Transketolase Activity ◽  
Chart Recorder ◽  
Precision And Accuracy ◽  
Semiautomated Method ◽  
Assay Conditions

Abstract In this semiautomated method, an AutoAnalyzer II is used to measure the enzymic production of glyceraldehyde 3-phosphate in hemolysates, to assay erythrocyte transketolase (EC 2.2.1.1) activity. Hemolysate and indicator reactions are separated by dialysis to eliminate hemoglobin interference and increase sensitivity. Internal standards of glyceraldehyde 3-phosphate in hemolysate carriers were quantitatively measured with good precision and accuracy in the presence or absence of the transketolase substrate, ribose 5-phosphate. Chart-recorder values for these standards were used to calibrate the AutoAnalyzer output in IUB units (U) of transketolase activity. Substrate-product relationships were examined to characterize reaction kinetics and optimize assay conditions. AutoAnalyzer transketolase results correlated well with those from two manual procedures.

Mice with deletion of the mitochondrial glycerol-3-phosphate dehydrogenase gene exhibit a thrifty phenotype: effect of gender

2004 ◽  
Vol 287 (1) ◽  
pp. R147-R156 ◽  
Author(s):  
Assim Alfadda ◽  
Rosangela A. DosSantos ◽  
Zaruhi Stepanyan ◽  
Husnia Marrif ◽  
J. Enrique Silva
Keyword(s):  
Energy Intake ◽  
High Fat Diet ◽  
Female Gender ◽  
Intermediary Metabolism ◽  
High Fat ◽  
Serum Triglycerides ◽  
Female Mice ◽  
Thrifty Phenotype ◽  
Glycerol 3 Phosphate Dehydrogenase ◽  
Ad Libitum Intake

To define the role of mitochondrial glycerol-3-phosphate dehydrogenase (mGPD; EC 1.1.99.5 ) in energy balance and intermediary metabolism, we studied transgenic mice not expressing mGPD (mGPD−/−). These mice had ≈14% lower blood glucose; ≈50% higher serum glycerol; ≈80% higher serum triglycerides; and at thermoneutrality, their energy expenditure (Qo2) was 15% lower than in wild-type (WT) mice. Glycerol-3-phosphate levels and lactate-to-pyruvate ratios were threefold elevated in muscle, but not in liver, of mGPD−/− mice. WT and mGPD−/− mice were then challenged with a high-fat diet, fasting, or food restriction. The high-fat diet caused more weight gain and adiposity in mGPD−/− than in WT female mice, without the genotype differentially affecting Qo2 or energy intake. After a 30-h fast, WT female lost 60% more weight than mGPD−/− mice but these latter became more hypothermic. When energy intake was restricted to 50–70% of the ad libitum intake for 10 days, mGPD−/− female mice lost less weight than WT controls, but they had lower Qo2 and body temperature. WT and mGPD−/− male mice did not differ significantly in their responses to these challenges. These results show that the lack of mGPD causes significant alterations of intermediary metabolism, which are more pronounced in muscle than liver and lead to a thrifty phenotype that is more marked in females than males. Lower T4-to-T3 conversion in mGPD−/− females and a greater reliance of normal females on mGPD to respond to high-fat diets make the lack of the enzyme more consequential in the female gender.

A stopped-flow/continuous-flow method for kinetic determinations

1995 ◽  
Vol 309 (1-3) ◽  
pp. 277-282 ◽  
Author(s):  
Yun-Sheng Hsieh ◽  
S.R. Crouch
Keyword(s):  
Continuous Flow ◽  
Stopped Flow ◽  
Flow Method ◽  
Continuous Flow Method

Comparison of Infra-Dry and AOAC Methods for Moisture in Food Products

1984 ◽  
Vol 47 (8) ◽  
pp. 611-614
Author(s):  
B. A. MINOR ◽  
K. A. SIMS ◽  
R. BASSETTE ◽  
D. Y. C. FUNG
Keyword(s):  
Wheat Flour ◽  
Food Products ◽  
Practical Significance ◽  
Good Precision ◽  
Average Percentage ◽  
Fresh Milk ◽  
Cooling Chamber ◽  
Precision And Accuracy ◽  
Potato Flakes ◽  
The Times

The Infra-Dry (IR) method was accurate, precise and faster than conventional (AOAC) procedures for moisture determinations in ten selected food products. The average percentage moisture by the IR method for 10 common food products and those by AOAC in parentheses are as follows: oatmeal 9.88 (9.87), cornmeal 10.86 (10.91), wheat flour 10.80 (10.80), grape nuts 4.73 (4.78), rice 12.39 (12.41), potato flakes 8.40 (8.36), bread crumbs 9.93 (9.99), noodles 9.58 (9.54), NFD milk 4.23 (4.24), and fresh milk 88.60 (88.71). The temperatures used for the IR method (135 to 155°C) were higher than those for the AOAC procedures (130°C for all products except NFD and fresh milk [100°C]); however, the times were considerably less (10 to 30 min) than for AOAC procedures (1 to 5 h). Standard deviations were generally <0.06%, except for cornmeal and noodles which were approximately 0.1%. Precisions were generally >97%. Upon removing the samples from the IR oven, results of good precision and accuracy were obtained by cooling the samples in a desiccator for 5 min or the built-in IR cooling chamber for 45 s. The recommended IR method uses a cooling chamber, is faster, and does not require a desiccator. Slightly lower precision and accuracy resulted when the entire IR oven was used. The best results were obtained using the back third of the oven. However, the slight difference in precision and accuracy is of little practical significance.

scholarly journals Elucidation of the photoreactivity of nanocrystalline 2-hydroxychalcones using continuous flow method

2019 ◽  
Vol 75 (a1) ◽  
pp. a442-a442
Author(s):  
Sobiya George ◽  
Jeanette A. Krause ◽  
Anna D. Gudmundsdottir
Keyword(s):  
Continuous Flow ◽  
Flow Method ◽  
Continuous Flow Method

Collaborative Study of the Gas-Liquid Chromatographic Method for Determination of Stereochemical Composition of Amphetamine

1972 ◽  
Vol 55 (1) ◽  
pp. 146-148
Author(s):  
Clyde E Wells
Keyword(s):  
Column Chromatography ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Good Precision ◽  
Liquid Chromatographic Method ◽  
Precision And Accuracy ◽  
Standard Deviations ◽  
Liquid Chromatographic ◽  
Amphetamine Sulfate

Abstract Eight laboratories collaboratively studied a method for the quantitative GLC determination of d- and l-amphetamine in tablets. The drugs are separated from tablet excipients by column chromatography and reacted with Ntrifluoroacetyl-( 0-prolyl chloride, and the resulting derivatives are analyzed by GLC. The samples consisted of commercial d-amphetamine sulfate tablets (with and without butabarbital), dl-amphetamine sulfate tablets, and a mixed d- and l-amphetamine sulfate standard. Recoveries were acceptable, and the standard deviations never exceeded 0.64%. The results demonstrate that the method gives good precision and accuracy, and the method is recommended for adoption as official first action.

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