A fluorometric assay in microtitre plates for the screening of phenylketonuria was evaluated and adapted to a neonatal screening programme. Using this assay, it is possible to determine quantitatively the phenylalanine concentration in dried blood spots on filter paper. The test exhibited a linear calibration curve with a good slope as well as sufficient precision and accuracy in the statistica...

were coated with Clq and then incubated with solutions containing the 16 g/L gelatin-buffer for a fluorometric immune complex assay. This gelatinbuffer is now being used in the development of the assay and does not appear to excessively inhibit the binding of immune complexes to Clq adsorbed on StiQs. This use of concentrated gelatin appears to solve a sticky problem in the development of fluor...

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...

As in all fluorometric procedures, glassware, reagents, and specimens must be kept free of fluorescent contamination. Glassware must be cleaned with an inorganic detergent and rinsed with distilled water. Paraflim should be used to seal tubes for mixing procedures. Ten milliliters of venous blood was collected into tubes containing 0.1 ml. sodium citrate (38 gm./100 ml. water), or 20 mg. ethyle...

The determination of myo-inositol trisphosphate by an enzymatic fluorometric assay is presented. The method involves the acid extraction of water-soluble inositol polyphosphates followed by separation by anion-exchange chromatography. Samples are subsequently neutralized by passage over a Dowex Cl- resin and elution with lithium chloride. Samples are then desalted with ethanol. Following dephos...