A "QUEST" for productivity.
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Efficiency↗
Biomedical subjects
T Thorsteinson
Publications and source records attributed to T Thorsteinson.
Chromatography of mycotoxins on precoated reverse-phase thin-layer plates.
Reverse-phase thin-layer chromatography of 18 common mycotoxins was carried out on Merck C18 and Whatman C18 and diphenyl bonded phases. The mobile phases included neutral and acidified binary mixtures of water and methanol, acetonitrile or tetrahydrofuran. Mycotoxins studied included aflatoxins B1, B2, G1, G2, sterigmatocystin, ochratoxin A, citrinin, penicillic acid, patulin, zearalenone, and the trichothecenes diacetoxyscirpenol, HT-2 toxin, nivalenol, neosolaniol, fusarenone-X, T-2 toxin, deoxynivalenol and 3-acetyl-deoxynivalenol. Both C18-bonded phases performed well, and could serve as a convenient confirmation for mycotoxins appearing in normal-phase (silica) thin-layer chromatographic screening procedures.
Chromatography, Thin Layer↗
Determination of sterigmatocystin in barley by acetylation and liquid chromatography.
The estimation of sterigmatocystin by fluorescence liquid chromatographic analysis of the acetate derivative has eliminated the background interference normally encountered in analysis of underivatized sterigmatocystin in barley. Barley samples are extracted with acetonitrile-water; the extract is then washed with hexane, transferred to chloroform, and eluted from a silica gel column with cyclohexane-ethyl acetate. The extract is heated with pyridine and acetic anhydride for 3 h to give a stable derivative. Reverse-phase liquid chromatography, using a methanol-water mobile phase gradient and fluorescence detection, is the method of determination. Recoveries from barley samples spiked with 20, 110, 190, and 765 micrograms sterigmatocystin/kg were 31, 69, 75, and 96%, with coefficients of variation between 2.8 and 5.4%. Sterigmatocystin is confirmed by comparing retention times in underivatized extracts of samples and standards, using methanol-water (3 + 2) mobile phase and ultraviolet detection.
Acetylation↗