Determination of Trace Level Microcystins in Water by Fully Automated Online Solid Phase Extraction Coupled with High Performance Liquid Chromatography
A fully automated online solid phase extraction(online SPE)-HPLC method was developed for the determination of three trace level microcystins(MCs) in water samples.The sample was first injected by autosampler to the online SPE column continuously followed by clean-up using loading pump with gradient program.Then the online SPE column was introduced to the analytical flow path by valve switching and the analytes were back-flushed to the analytical column using analytical pump for further determination.The Acclaim PA cartridge(10 mm×4.3 mm×5 μm) was employed as online SPE column and the Acclaim PA2(150 mm×4.6 mm×3 μm) as analytical column,the flow of loading pump was set at 2.0 mL/min while the analytical pump was 1.0 mL/min.Gradient programs were used for the sample clean-up and determination in both pumps.The detection wavelength was set at 238 nm,the injection volume was 10 mL and the total analysis time was 20 min.Good linearity from 0.5 to 10 μg/L(R20.9996) for each microcystin were obtained with a limit of detection(LOD) of 0.1 μg/L(S/N3).The repeatability was got from 6 injections of standard solution with peak area RSD1.6%.The results showed that the proposed method could be used for the determination of trace level microcystins in water samples.