Determination of mycotoxins in pet foods sold for domestic pets and wild birds using linked‐column immunoassay clean‐up and HPLC

Abstract

A technique referred to as ‘linked‐column immunoassay clean‐up’, was developed for the simultaneous determination of aflatoxins and ochratoxin A in a range of dry cereal‐based pet foods and wild bird food. In addition a method also based on clean‐up using immunoaffinity columns was used for the determination of fumonisin mycotoxins in samples known or suspected to contain maize. One hundred samples of pet foods consisting of 35 samples each of cereal‐based dog and cat foods, 15 samples of domestic bird seeds and 15 samples of wild bird food were examined for aflatoxins B₁ B₂, G₁ and G₂ and ochratoxin A. Twenty samples of these samples were also examined for fumonisins B₁ and B₂. Limits of detection were about 0.5 μg/kg for each aflatoxin and ochratoxin A and 3 and 8 μg/kg for fumonisins B₁ and B₂ respectively. Eighty‐four percent of the samples contained no measurable concentrations of mycotoxins. A low level of aflatoxin B₁ was found in a sample of cat food and a concentration of 370 μg/kg aflatoxin B₁ in one sample of peanuts marketed for wild birds. Ochratoxin A was detected in 10% of samples but in low concentrations, the highest of 7 μg/kg occurring in a sample of bird food. Fumonisins were found in 30% of the 20 samples tested with a maximum of 750 μg/kg total fumonisins being found in a sample of cat food. Five samples each of dog and cat foods were examined for mould count and fungal species as received and after storage under controlled simulated damp conditions. Mould counts in all 10 samples examined were very low when received. The samples in which moisture content had been increased contained visible mould after storage. Penicillium, Eurotium and Aspergillus were the predominant species. However, no ochratoxin A or aflatoxins were detected in these spoiled samples.