Liquid Chromatographic Determination of Alternaria Toxins in Carrots

A liquid chromatographic (LC) method was developed for the determination of Alternaria radicina and A. alternata toxins in carrots. Toxins were extracted from carrot with an acidified mixture of water¿methanol¿acetonitrile. The filtered extract was divided in 2 parts that were purified by solid-phase extraction on a C18 column for the analysis of radicinin (RAD), altertoxin-I (ATX-I), alternariol (AOH), and alternariol methyl ether (AME), and on a polymeric Oasis® HLB column for tenuazonic acid (TeA). Toxins were quantified by reversed-phase LC with UV diode array detection by using 2 consecutive isocratic mixtures of acetonitrile¿sodium dihydrogen phosphate solution. Mean recoveries of TeA, ATX-I, AME, RAD, and AOH from carrots spiked at levels between 0.5 and 3.0 ¿g/g were 69, 71, 90, 36, and 78%, with mean within-laboratory repeatability of 14, 5, 4, 6, and 18%, respectively. The mean between-laboratory reproducibilities for the determination of TeA, ATX-I, AME, and RAD in spiked samples were 25, 22, 6, and 12%, respectively. Limits of detection (signal-to-noise ratio of 3) for RAD, TeA, ATX-I, AME, and AOH were 0.006, 0.02, 0.02, 0.01, and 0.005 ¿g/g, respectively. RAD was detected (0.16¿13.9 ¿g/g) in 3 out of 266 carrot samples produced under organic conditions in 3 European locations, whereas A. alternata mycotoxins were not found in any tested samples