Reference material in residue control: assessment of matrix effects

The production of certified reference materials (CRM) requires a comprehensive consideration of which analytes and materials to select. The present study describes the pre-tests for the production of CRM for nitroimidazoles in plasma or muscle. By means of a commutability study, four factors, namely matrix (plasma - muscle), species (turkey - pig), matrix condition (fresh - lyophilized) and measurement technique (GC-NCI/MS-LC-MSMS) were checked for their usability. The results showed that the matrices, matrix conditions, as well as the species analyzed did not produce any relevantly different measurement results. Varying significantly and subject to a systematic error were those results which were determined by means of different measurement techniques.