Determination of hydroxymethanesulfonic acid in environmental samples by capillary electrophoresis

Capillary electrophoresis (CE) with indirect UV detection was applied to the quantitative direct determination of hydroxymethanesulfonate ion (HMSA) present in atmospheric aerosols and other environmental samples. The proposed method used 2,6-naphthalenedicarboxylic acid (NDC)-based background electrolyte that allowed indirect detection at 214 nm. Separation was achieved by applying constant current (6.6 ± 0.6 μA which corresponds to –15 kV). According to the HMSA levels, samples were injected either by hydrodynamic (a pressure of 70 mbar, 10 s) or electrokinetic injection (–10 kV, 15 s). Method performance was determined for both injection modes. With pressure injection, the limit of detection (LOD) for HMSA was 39 μg/L and the external calibration was linear from 0.5 to 10 mg/L. With electrokinetic injection, the LOD was 2 μg/L and the internal calibration was linear from 20 to 400 μg/L. Good intra- and inter-day precision, and inter-person reproducibility and recovery were obtained for both hydrodynamic and electrokinetic injection modes. The long-term reliability of the proposed CE method was checked over a one-year period during which over 1 000 samples were analyzed.