Determination of p-aminobenzoic acid in urine by room-temperature phosphorimetry, with application to the bentiromide test for pancreatic function.

Analytical recovery of urinary p-aminobenzoic acid liberated from bentiromide(N-benzoyl-L-tyrosyl-p-aminobenzoicacid) was determinedby roomtemperaturephosphorimetryas an index to exocrine pancreatic function. Metabolites were hydrolyzed to the parent compound in 4 mol/L NaOH, then quantified, after pH adjustment, by spothng 3 L of this solution onto filter paper treated with potassium iodide and measuring the resulting phosphorescence relative to a standard curve. The method is sufficiently precise, and results compare well with those by the Bratton-Marshall colorimetric method (r = 0.993) for determining p-aminobenzoic acid in urine from patients undergoing the bentiromide test. The present procedure is rapid and is more selective than are colorimetric procedures.