Capillary Electrophoresis with Laser-Induced Fluorescence:  Method for the Mycotoxin Ochratoxin A

Ochratoxin A (OA) is a natural contaminant of a large variety of foods of plant and animal origin. Herein is reported the development of a capillary electrophoresis (CE) method for the quantification of OA in three very different commodities: roasted coffee, corn, and sorghum. The extraction and isolation procedures combine a silica column and an immunoaffinity cleanup column analogous to other chromatographic methods. After separation from interferences by CE, OA was exposed to light from an ultraviolet He/Cd laser, and the fluorescence of OA was measured [CE-laser-induced fluorescence (CE-LIF)]. When OA was added to several foods over the range 0.2−10 ng/g (ppb), the average recoveries were 86% for roasted coffee (SD = 12.2; n = 8), 99% for corn (SD = 10.1; n = 8), and 91% for sorghum (SD = 14.8; n = 4). Each instrumental analysis, after extraction and purification, required 13 min, equivalent to HPLC analysis. CE-LIF can be applied to the quantitation of OA in roasted coffee, corn, and sorghum, reducing organic solvent usage relative to HPLC. Keywords: Ochratoxin A; coffee; corn; sorghum; capillary electrophoresis