The German Metabolite Project - A Review.

New complex residue definitions for plant protection products are constantly being defined by the European Commission. In terms of consumer protection, the maximum residue levels of these definitions must be monitored. However, many complex residue definitions have not been fully covered during monitoring. The main challenges for the official control laboratories are the identification of "relevant" metabolites, the availability of analytical reference standards with defined purity for specific metabolites, and the lack of method information. Therefore, the German government control laboratories decided to work together on a project to improve the situation. This marked the beginning of the German metabolite project. The results are presented in this paper. They include method implementation, data from screening and quantitation methods, information on the reprocessing of full-scan data sets, information on validation (initial and ongoing), as well as findings. The project has been well received and has created positive effects on the analysis of metabolites over the years. Nowadays, more laboratories are capable of monitoring complex residue definitions, and they are reporting data on findings to relevant authorities. Thanks to the project, the availability of analytical standards has improved significantly, due to the enhanced communication between laboratories and manufacturers of analytical standards. Also, the use of screening methods has been proven to be a significant factor in extending the scope of the official control laboratories.