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Survey for co-occurrence of ochratoxin A and aflatoxin B, in dried figs in Turkey by using a single laboratory-validated alkaline extraction method for ochratoxin A

2005-07-01
Senyuva, HZ
Gilbert, J
Özcan Kabasakal, Süreyya
Ulken, U
A survey was carried out to determine the co-occurrence of ochratoxin A and allatoxin B-1 in dried figs from Turkey. Samples from two seasons of crops (2003 and 2004) intended for export to the European Union and the 2004 crop obtained from the domestic Turkish market were analyzed. Affinity column cleanup methods were employed for determining separately ochratoxin A and aflatoxin 131, but for ochratoxin A an alkaline extraction procedure was employed (in contrast to the conventionally employed acidic extraction), which gave consistently higher toxin recovery. In-house validation of the ochratoxin A method gave a limit of detection of 0.15 ng/g and a limit of quantification of 0.5 ng/g with a repeatability of 5.8% in the range 5 to 10 ng/g (with a mean recovery of 94% for spiked samples). Positive results for ochratoxin A were confirmed by liquid chromatography-mass spectrometry. For the 2003 export figs (58 samples), 7 samples contained only aflatoxin B-1, 2 samples contained only ochratoxin A, and 2 samples contained both toxins (with maximum concentrations of 35.1 ng/g for aflatoxin B-1 and 13.0 ng/g for ochratoxin A). Similarly for the 2004 export figs (41 samples), 16 samples contained only aflatoxin B-1, 4 samples contained only ochratoxin A, and 2 samples contained both toxins (with maximum concentrations of 20.6 ng/g for aflatoxin B-1 and 26.3 ng/g for ochratoxin A). Of 20 retail samples of dried figs from Turkey, only one sample contained ochratoxin A (2.0 ng/g) and none were contaminated with aflatoxin B-1. This survey revealed a 14 to 15% incidence of occurrence of ochratoxin A for 2 years, which is higher than previously reported.