Plasma catecholamines were fluorometrically determined by a modification of the standard alumina-trihydroxyindole method in which radioactive tracer catecholamines are used to follow the chromatographic behavior of the endogenous catecholamines on alumina. This modification permits appropriate fluorometry of that portion of the eluate with the highest concentration of catecholamines, because in...

We describe a method for determining lipase (triacylglycerol acyl-hydrolase, EC 3.1.1.3) activity in serum. Emulsified olive oil in tris(hydroxymethyl)aminomethane buffer is used as substrate. The course of the enzymatic reaction is followed by measuring the decrease in fluorescence with time of a fluorescent indicator, 4-methylumbelliferone, added to the substrate, caused by the change in the ...

In this study, we compared three methods for extraction and quantification of RNA and DNA from marine sediments: (i) a spectrophotometric method using the diphenylamine assay; (ii) a fluorometric method utilizing selective fluorochromes (thiazole orange for total nucleic acids and Hoechst 33258 for DNA); and (iii) a high-pressure liquid chromatography (HPLC) method which uses a specific column ...

A Porter and Silber procedure, a fluorometric procedure, a double-isotope derivative procedure, and a competitive protein-binding assay procedure were used to determine 17-hydroxycorticosteroids in plasma from normal individuals and from patients with endocrinopathies. Results from each of these procedures were intercompared. Results of the fluorometric procedure and the competitive proteinbind...

Both fluorometric and microbiological measurements of urinary riboflavin excretion have served as a basis for evaluation of nutritional status, detection of deficiency states, measurement of physiological availability, and determination of daily requirements. Fluorometric assay methods have commonly followed three basic procedures; namely, (a) that of Najjar (l), based on the extraction of ribo...