Objective: To develop a method for determination of mandelic acid (MA) and phenylglyoxylic acid (PGA) in urine by reagent-free ion chromatography.
Methods: Ion chromatography was performed on an AS19 column with a gradient elution solution containing 10-35 mmoL/L KOH at a flow rate of 1.00 ml/min, and MA and PGA were detected at ultraviolet wavelengths of 225 nm and 254 nm, respectively. The samples were diluted 10 times with purified water, then purified on a silver column to remove high concentrations of chloride ion, and injected after being filtered through a 0.2-µm m filter membrane.
Results: The recoveries of standard addition of MA and PGA were 96.5% and 99.3%, respectively, with both relative standard deviations less than 5.0%. Good linear relationships were noted in the range of 1.0-100.0 mg/L for both MA and PGA (r >0.9995). The detection limits of MA and PGA were 0.02 mg/L and 0.05 mg/L, respectively; the minimum detectable concentrations of MA and PGA were 0.2 mg/L and 0.5 mg/L (when the sampling amount was 5.0 ml and diluted to 50.0 ml with water, and the injection volume was 300 µL).
Conclusions: This method is fast, convenient, and highly sensitive and selective. It can be used for the analysis of MA and PGA in the urine of styrene-exposed workers.