Quantification of urinary 5-aminolevulinic acid by gas chromatography–mass spectrometry

In this report, we describe a method for the specific quantification of urinary 5-aminolevulinic acid. It is based on gas chromatographic mass spectrometric measurement of the trimethylsilyl ester of the ethylacetoacetate pyrrole derivative of 5-aminolevulinic acid. Selected ion monitoring (SIM) was used for quantification using 3-hydroxymyristic acid as an internal standard. The detection limit of this method was 0.1 nmol/ml. This method was applied to the determination of urinary 5-aminolevulinic acid from a tyrosinemia type I patient and normal subjects, and 21.4 mmol/mol creatinine and 0.54±0.49 mmol/mol creatinine (n=7), respectively, were detected. Less than 0.2 ml urine was sufficient for the determination of 5-aminolevulinic acid in healthy subjects.