Comparison between the fluorometric HPLC method and the conventional method for determining urinary ?-aminolevulinic acid and coproporphyrin as indices of lead exposure

Abstract

Fluorometric methods for determining δ-aminolevulinic acid (ALA) and coproporphyrin (CP) in urine have been recently developed by using high-performance liquid chromatography (HPLC). In the present study, urinary ALA and CP in lead-exposed workers were determined with these fluorometric HPLC methods and the conventional methods, and the results obtained were compared. In lead workers with a urinary ALA ≥ 5 mg/l, the values obtained with the fluorometric HPLC method corresponded well with those measured with the conventional colorimetric method. In contrast, in lead workers with ALA < 5 mg/l, ALA values obtained with the fluorometric HPLC method were lower than those measured with the conventional method, suggesting the possibility of matrix interference in urine. The urinary CP values obtained with the conventional method of Rimington (1971) were higher than those measured with the fluorometric HPLC method, though the correlation was good.