Enhancing the sensitivity of capillary electrophoresis using a microcolumn solid phase extraction setup

In this paper, a setup called micro-column solid phase extraction (MicroSPE) was developed to enhance the sensitivity of capillary electrophoresis. The setup consists of a manual pump, several insulin syringes, and a Teflon extraction cartridge. The cartridge was made of 2-4 mm irregular C-18 solid phase materials in a Teflon tube (375 mum ID) with glass fiber frits. Two pieces of capillary tubing were connected to both the ends of the cartridge. Using sulinclac-spiked urine as the test sample, the extraction and analytical conditions were investigated in detail. When 1 muL 70/30 methanol/water was applied as the elution solvent, satisfactory results could be obtained. The internal standard method was used to quantitatively determine the compound in urine. The detection limit for sulindac was 2.9 ng/mL and the enrichment factor reaches more than 260. The result illustrates that the MicroSPE setup has a significant concentrating effect and is suitable for preconcentrating and cleaning-up samples with complex matrices.