AN INTERCOMPARISON OF METHODS FOR THE DETERMINATION OF OCHRATOXIN-A IN PIG-KIDNEY

The preparation of two pig kidney materials is described, together wit h a report on the results of an intercomparison study of methods to de termine ochratoxin A levels in these materials. The materials were pre pared, and the intercomparison study carried out within the European C ommission, Measurements and Testing Programme, which is the successor of the Community Bureau of Reference (BCR). The materials were prepare d from blank and naturally-contaminated pig kidneys and were freeze-dr ied. Details are given on the freeze-drying and packaging procedure, a nd the checks to ensure homogeneity and stability of the freeze-dried materials. The intercomparison study involved 20 European laboratories , which analysed the naturally-contaminated (freeze-dried) sample (och ratoxin A content approximately 10 mu g/kg based on fresh weight) and the 'blank' sample (ochratoxin A content <0.6 mu g/kg based on fresh w eight) using a variety of procedures for extraction and clean-up. All laboratories used HPLC as the determinative step. Recoveries were foun d to range from 43 to 128%. The study highlighted problems with recove ry of spiked ochratoxin A from freeze-dried pig kidney material. There is a clear need to improve analytical performance, particularly with respect to the extraction efficiency from this type of matrix.