Laser Fluorimetry: Detection of Aflatoxin B 1 in Contaminated Corn
1978; American Chemical Society; Linguagem: Inglês
10.1021/bk-1978-0085.ch005
ISSN1947-5918
AutoresGerald J. Diebold, Richard N. Zare,
Tópico(s)Analytical Chemistry and Chromatography
ResumoA high sensitivity laser fluorimeter designed specifically for use with high pressure liquid chromatography (HPLC) is described. An amplitude modulated He-Cd ion laser at 325 nm irradiates a flowing droplet of eluent from an HPLC column, and fluorescence is detected in phase with the modulation by a lockin amplifier. The fluorimeter is capable of detecting 750 fg of each of the four commonly occurring aflatoxins, and has a linear range of over three orders of magnitude. Using a two-step chromatography procedure, this device is capable of quantitating aflatoxin B1 to 100 ppt in corn. Following extraction of the aflatoxin from corn, the extract is given a preliminary cleanup on a normal phase thin layer chromatography (TLC) plate. The aflatoxin B1 is recovered, and injected onto a reverse phase HPLC column. Experiments with aflatoxin B1 standards show a constant ratio for conversion of aflatoxin B1 to aflatoxin B2A over roughly three orders of magnitude. The recovery of aflatoxin B1 from the TLC plates, although slightly nonlinear above 10 ppb permits linear quantitation of aflatoxin B1 in white and yellow corn in the range from 0.1 to 10 ppb with an average root mean square (rms) error of 26%.
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