Mass spectral confirmation of aflatoxins
Haddon, W.F.; Masri, M.S.; Randall, V.G.; Elsken, R.H.; Meneghelli, B.J.
Journal - Association of Official Analytical Chemists 60(1): 107-113
1977
ISSN/ISBN: 0004-5756 PMID: 576222 Document Number: 123115
Two methods for mass spectral (MS) confirmation of aflatoxins in agricultural products and in physiological fluids are described. In the 1st method, electron ionization (EI) mass spectra are obtained following isolation by TLC and compared with available reference mass spectra to provide structural confirmation. Extensive sample clean-up is required for confirmation at the 10-1000 ppb level and minimum sample size is 10-50 ng aflatoxin isolated by TLC. The 2nd method restricts the MS scanning to particular ions which are characteristic of the suspected aflatoxins and requires spectrometer resolution above 5000. The latter method, called high resolution selected ion monitoring (HRSIM), has a sensitivity below 0.0001 .mu.g for aflatoxin B1 and makes possible direct analysis of complex mixtures. Employing HRSIM analysis on complex mixtures lowers the detection limit for aflatoxins M1 and B1 by 100-fold or more below the limit for highly purified samples. This dramatic sensitivity enhancement is attributed to a reduction in surface bonding between the afatoxins and the glass sample containers used to introduce the samples. The HRSIM is generally applicable to compounds that cannot be separated by gas chromatography prior to MS analysis.