Microcolumn Solid-phase Extraction Coupled Online to Capillary Liquid Chromatography Using a Valve Switching Technique

Abstract

A packed microcolumn solid-phase extraction coupled online to a capillary liquid chromatography (CapLC) was described and evaluated. A short packed capillary column (65 mm×0.45 mm i.d., 5 μm C 18) was used as the extraction cartridge and was mounted on a 10-port switching valve. A given volume of sample in a sample loop mounted on an injection valve passed through the cartridge, which retained the target compounds of the sample. The compounds were then desorbed by mobile phase, and were separated on an analytical column. Anisaldehyde water sample was used as the standard sample to evaluate the system. The calibration curve was linear (r > 0.998) over the concentration range of 0.01–0.5 mg l −1. The relative standard deviations of the retention time, the peak height, and the peak area of anisaldehyde in the linear ranges were 1.4%–2.2%, 4.2%–5.7%, and 6.0%–10.1%, respectively. The detection limit of anisaldehyde using this device was 6.0×10 −3 μg/L (S/N=3). In addition, the sensitivity of some apolar aromatic hydrocarbon compounds could be improved by 30–100 folds. The method was applied for the determination of traces of naphthalene in seawater, with a detection limit of 0.13 μg l −1 (S/N=3).