Activity measurement of arylsulfatase and β-glucuronidase in activated sludge: HPLC-based versus classical spectrophotometric method.

Arylsulfatase and β-glucuronidase are two important enzymes in wastewater and surface water, which play important roles on cleavage of sulfate/glucuronide estrogens. In this work, a high-performance liquid chromatography (HPLC)-based new method was firstly established for arylsulfatase/β-glucuronidase with determination of p-nitrophenyl sulfate (pNPS)/p-nitrophenyl-β-D-glucuronide (pNPG). The limits of detections (LODs) of the developed method for pNPS and pNPG were 0.164 and 0.098 μM, respectively. Intraday and interday reproducibility expressed as relative standard deviation (RSD) values of retention times and peak areas was 0.39%-3.68% and 0.23%-4.74%, respectively. The respective recovery efficiencies of this HPLC-based method spiking at three different concentrations for p-nitrophenol (pNP), pNPS, and pNPG in activated sludge were 76.5%-88.1%, 79.2%-93.1%, and 84.2%-96.1%, with RSD below 3.9%. The HPLC-based method was finally applied to estimate the enzyme activity of arylsulfatase/β-glucuronidase in one activated sludge system and along which the classical spectrophotometric method was also evaluated. Compared with the classic spectrophotometric analytical method, the HPLC-based new method could simultaneously measure arylsulfatase/β-glucuronidase one time, which was convenient and time-saving. Moreover, the developed method could effectively avoid possible underestimation that the spectrophotometric method might encounter. PRACTITIONER POINTS: A new HPLC-based method for activity estimation of arylsulfatase and β-glucuronidase was developed. The HPLC-based method can simultaneously estimate enzyme activity of both arylsulfatase and β-glucuronidase. The HPLC-based method can avoid possible underestimation that spectrophotometric method may encounter.