Aliquots (0.1 mL) of whole-blood pools prepared to contain various concentrations of phenylalanine were applied to filter-paper collection cards, dried, and stored in sealed bags. We measured the phenylalanine content of the dried blood spots by bioassay, fluorometry, and "high-performance" liquid chromatography, and found that the concentrations remained constant for two years when samples wer...

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...

Measurement of DPNH’ or TPNH by absorption at 344 rnp has been a standard procedure for many years and has been used to study innumerable enzyme reactions. In spite of the proved value of this calorimetric method, there may be advantages in fluorometric methods for the pyridine nucleotides. First, it has been found practicable with a fluorometer to determine separately oxidized and reduced pyri...