Mycotoxins in ingredients of animal feeding stuffs: I. Determination of Alternaria mycotoxins in oilseed rape meal and sunflower seed meal.

A multi-toxin method was developed for the detection of some of the known Alternaria mycotoxins, altenuene, iso-altenuene, alternariol, alternariol monomethyl ether, tenuazonic acid and altertoxin I in oilseed rape meal and sunflower seed meal. The method involves extraction of the toxins with an acidified mixture of acetonitrile: aqueous potassium chloride solution, followed by liquid-liquid extraction and further purification using gel permeation chromatography. The final extract is then examined on a reverse phase high performance liquid chromatographic gradient system with both fluorescence and UV detection. The average recoveries found were 94, 84, 109, 85, 66 and 93% for spiked oilseed rape meal samples and 91, 89, 96, 75, 61 and 102% for spiked sunflower meal samples with limits of determination of about 40, 50, 50, 40, 350 and 200 micrograms/kg for the above toxins, respectively. Detection limits were about 30% of these values. Thirty samples of oilseed rape meal and 22 samples of sunflower meal were examined using the methods developed. Twenty of the oilseed rape products which had been grown in the UK were free from contamination while 10 contained one or more of tenuazonic acid, alternariol and alternariol monomethyl ether. In contrast, all of the sunflower meal samples, of Argentinean, Indian or EC origin, were contaminated with one or more of alternariol, alternariol monomethyl ether and tenuazonic acid. Average levels of alternariol, alternariol monomethyl ether and tenuazonic acid were 68, 55 and 730 micrograms/kg, respectively for the contaminated samples of oilseed rape meal and 180, 100 and 1900 micrograms/kg, respectively for the contaminated samples of sunflower seed meal.