3 ml. of sample containing a trace of the fluorescent indicator was charged to the column. After the chromatographic zones were measured on the column, the nonfluorescent saturates zone up to the beginning of the yellow fluorescence was collected in a small vial for subsequent analysis by gas chromatography.The best procedure for hydrogenating the olefins employed an apparatus similar to that described by Mitchell et al. (10). A condenser, which was cooled by circulating water at a temperature of 1°C ., was placed between the reaction vessel and the gas buret.

No abstract

We have prepared a dry film for the enzymic determination of total serum cholesterol. It consists of a transparent support bearing a buffered gelatin layer, and a white reflective spreading layer that contains all of the necessary components for the detection of cholesterol. The method is based on (a) hydrolysis of cholesterol esters to cholesterol by cholesterol ester hydrolase (EC 3.1.1.13), (b) oxidation of cholesterol to cholest-4-en-4-one and hydrogen peroxide by cholesterol oxidase (EC 1.1.3.6), and (c) oxidation of a triarylimidazole leuco dye with hydrogen peroxide in the presence of peroxidase (EC 1.11.1.7) to produce a dye with maximum absorption at about 650 nm. For use over a wider range of concentration, the dye density is read at 540 nm. With reflection densitometry and appropriate mathematical transformation, readings and cholesterol concentrations are linearly related to 5500 mg/L. Results correlate well with those by the Abell-Kendall comparison method (slope 0.97, intercept 92.5, correlation coefficient 0.974, Sy.x = 250.7), and the method is precise (CV of 1.2-2.3% for a control fluid and patients' samples) and relatively free of interferences.