Abstract:

This paper describes a novel method in which solvent microextraction(SME) is followed by on\|line back-extraction-field amplified sample injection(OLBE-FASI) in capillary zone electrophoresis(CZE). The water-immiscible solution sample, sealed with water plug in the sample vial, was used for direct electroinjection. The water plug with moderate content of organic solvent, low-conductivity, and the presence of a small amount of H+ provided the highest sensitivity for analyzing positively chargeable compounds, such as cocaine and thebaine. The linear range was 0.040—4, 0.040—2 μg/mL, with the square of the correlation coefficient(r2)>0.997, respectively. Detection limits were in the range of 5—10 ng/mL.

Key words: Solvent microextraction; On-line back-extraction; Field amplified sample injection