Validation of a method for the determination of triphenylmethane dyes in trout and shrimp with superior extraction efficiency

The described methods are able to analyse the triphenylmethane dyes malachite green (MG), crystal violet (CV) and brilliant green (BG) as well as their leuco metabolites leuco malachite green (LMG), leuco crystal violet (LCV) and leuco brilliant green (LBG) on the basis of a simple and fast extraction. The validation of the methods in two studies without and with a heated ultrasonic treatment during the extraction of fortified trout and shrimp samples was successfully performed applying an in-house validation concept. The evaluation of the relevant validation parameters, e.g. the decision limit CCα, the detection capability CCβ, the repeatability, the within-laboratory reproducibility and the recovery for both extraction versions, showed results which fulfil the requirements of Commission Decision 2002/657/EC. The investigation of incurred material of trout containing the above compounds with an additional heated ultrasonic treatment during extraction leads to higher findings of MG and BG. This effect was also confirmed by other laboratories in the framework of a proficiency test. For CV and all three leuco metabolites no increase in the detected amounts could be observed after a heated ultrasonic treatment of the incurred trout material.