Electrochemical determination of arylsulfatase activity using high-performance liquid chromatography

A highly sensitive assay for arylsulfatase A was developed using high-performance liquid chromatography with electrochemical detection. The retention time of the enzymatic product, p-nitrocatechol, on a reverse phase column was approximately 2.0 min. The assay was able to detect 0.43 pmol p-nitrocatechol in a 20-microliter ethanol extract of the reaction mixture. The coefficients of variation for seven determinations of the intra- and interassays were 9 and 8%, respectively. The levels of arylsulfatase A activity in human saliva samples and leukocyte and platelet lysates determined by this assay were within 6 and 11%, respectively, of the levels determined by a spectrophotometric assay. The high-performance liquid chromatography assay may have utility in measuring arylsulfatase A activity in biological samples with low activity or specific activity or in samples with compounds which interfere with the spectrophotometric assay.