Determination of carbofuran by online immunoaffinity chromatography with coupled-column liquid chromatography/mass spectrometry

Abstract

Development of a new technology for combined on-line sample preparation and analyte confirmation is presented. This technology involves the use of antibodies for trace analyte extraction and enrichment directly from a complex matrix. The antibodies are used in columns designed for use with ordinary high-pressure liquid chromatographic equipment. The immunoaffinity columns are combined with conventional reversed-phase LC columns by use of column-switching techniques and coupled directly to an atmospheric pressure ionization quadrupole ion trap mass spectrometer equipped with a pneumatically assisted electrospray (ion spray) interface. A column of aldehyde-activated silica was used to prepare a column specific to carbofuran. This column demonstrated excellent specificity toward carbofuran and showed no binding of another, unrelated compound, fluometuron. Direct extraction and detection of carbofuran was demonstrated at low levels (40 pg/mL) in spiked water, but the real utility of immunoaffinity chromatography (IAC) is demonstrated by the on-line extraction and detection of carbofuran from a chemically complex, crude potato extract. Samples extracted using an IAC column indicate that superior purification is obtained with IAC in comparison with samples pumped directly onto a reversed-phase trapping column. A detection limit for carbofuran of approximately 2.5 ng/g of potato was obtained using an atmospheric pressure ionization quadrupole ion trap mass spectrometer.