Factors affecting determination of delta-aminolevulinate by use of Ehrlich's reagent.

We investigated the formation of delta-aminolevulinic acid (ALA)-pyrrole and subsequent color development used in determining ALA in urine. Of three condensation reagents examined--acetylacetone, ethyl acetoacetate, and methyl acetoacetate--the last was the best. When the ALA-pyrrole is reacted with Ehrlich's reagent in ethyl acetate according to one procedure, the optimum concentration of perchloric acid in the reagent is 0.5 to 1.0 mol/L. Its optimum concentration is 1.0 to 2.3 mol/L when the reaction takes place in water.