Development of a fiber-in-tube microextraction protocol for gas chromatography-electron capture detection of hexachlorocyclohexanes in water samples

A fiber-in-tube microextraction protocol was developed and coupled with gas chromatography-electron capture detector (GC-ECD) for determination of trace hexachlorocyclohexanes (HCHs) in water samples. The developed technique was performed by immersing a PTFE fiber-packed and organic solvent-filled PTFE tube in the stirred aqueous solution. Extraction took place between the solvent permeated fibers and sample solution. The extract was then analyzed by GC-ECD. The effects of fiber quantity, extraction time, agitation, addition of salt and pH of sample solution were investigated in detail. Extraction of the analytes in 8 ml aqueous solution for 20 min yielded enrichment factors of 221-538. The limits of detection (S/N = 3) and the limits of quantitation (S/N = 8) were 2-12 ng l−1 and 6-32 ng l−1, respectively. The precision (R.S.D.s, n = 5) was 0.1% for retention time and 1.8-4.8% for peak height. The developed methodology was applied to the determination of trace HCHs in local river water samples.