Automated on-line in-tube solid-phase microextraction coupled with high performance liquid chromatography for the analysis of bisphenol A, alkylphenols, and phthalate esters in foods contacted with plastics

An automated on-line method for the analysis of endocrine disruptors related to plastics was developed using in-tube solid-phase microextraction coupled with high performance liquid chromatography (in-tube SPME/HPLC). In-tube SPME is an extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. Suspected endocrine disrupting compounds, bisphenol A, two alkylphenols, and nine phthalate esters, tested in this study were well separated with a Hypersil ODS column with diode array detection using acetonitrile/water as a mobile phase. In order to optimize the extraction of these compounds, several in-tube SPME parameters were examined. The optimum extraction conditions were 20 draw/eject cycles of 40 μL of sample using a Supel-Q PLOT capillary column. The extracted compounds were easily desorbed from the capillary by mobile phase flow, and carryover was not observed. Using in-tube SPME/HPLC method, the calibration curves of these compounds were linear in the range from 1 to 500 ng/mL, with correlation coefficient above 0.991 (n = 18), and the detection limits (S/N = 3) were 0.1-4.0 ng/mL. This method was successfully applied to the migration test from plastics and the analysis of food samples.