Method validation with associated measurement of uncertainty for determination of pyrethroid in lanolin using gas chromatography–mass spectrometry

Abstract

Method of analysis with non-chiral chromatographic separation of isomeric forms of pyrethroids was developed for determination of five group of pyrethroid in lanolin, which is a natural product with wide applications in food, drug and cosmetic industry. Pyrethroid are used extensively for ectoparasitic treatments of sheep and find their way into sebaceous secretion of sheep as lanolin. The present study describes validation for developed method, including measurement of uncertainty (MU) at quantification limit of 0.05 μg/g. The method is based on modified matrix solid phase dispersion (MSPD) sample extraction steps and GC-MS/MS with multiple reaction monitoring (MRM) acquisition mode. The method was found to be linear over the analytical range of 0.05–1.0 μg/g, with acceptable coefficient of determination, (r2 ≥ 0.99) for group calibration of 5 pyrethroids with LOD & LOQ of the method as 0.025 μg/g and 0.05 μg/g, for all the 12 isomeric forms of pyrethroid. Validation data showed method to be accurate with precision within the acceptable limits i.e. recoveries in the range of 73.5%–109% with less than 20% RSD for all the 5 group of pyrethroid. MU associated with results at LOQ shows that calculated expanded uncertainty at 95% confidence level for pyrethroids lies between 1.8 and 3.3 ng/g.