Multiple solid phase microextraction combined with ambient mass spectrometry for rapid and sensitive detection of trace chemical compounds in aqueous solution.

Multiple solid phase microextraction (mSPME) combined with thermal desorption-electrospray ionization/mass spectrometry (TD-ESI/MS) was developed to rapidly characterize trace analytes in aqueous solution. A number of commercial available SPME fibers (from 2 to 10 fibers) were simultaneously used for extracting the analytes in solution. The fibers were then bundled together on a holder and subjected for the ambient mass spectrometric analysis. Good linearity for calibration (R = 0.9995) and low limit of quantification (<1 ppb) were achieved by using 10 SPME fibers coated with polyacrylate (PA) to extract bisphenol A. It was also found that the analyte signals increased with the number of SPME fibers for extraction. Uncontroversial, a shorter extraction time was required by using mSPME to reach the same level of analyte signal as that by using single SPME fiber for a longer extraction time. Trace bisphenol A (4-20 ppb) in the polycarbonate (PC) baby milk bottles was rapidly detected using mSPME-TD-ESI/MS and the analysis was completed within 1 min. The use of multiple SPME fibers coated with different materials enable the concentration of different type of analytes in the solution. Ibuprofen, bisphenol A (BPA), and 4-n-nonylphenol (4-n-NP) were simultaneously detected by using PA and polydimethylsiloxane (PDMS) coated fibers for extraction.