Validation of a Modified QuEChERS Method for the Determination of 167 Pesticides in Milk and Milk Products by LC-MS/MS Ozgur Golge 1 & Ahmet Koluman 1 & Bulent Kabak 2 Received: 27 April 2017 /Accepted: 12 October 2017 # Springer Science+Business Media, LLC 2017 Abstract A liquid chromatography tandem mass spectrome- try (LC-MS/MS) method with modified QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction cleaning process was comprehensively validated for determination of 167 pesticide residues in three matrices: milk, cheese and cream. Optimisation of the mass spectrometry parameters was performed by injecting pesticide standard solutions into the electrospray ion (ESI) source. The mass spectrometer was operated in the positive ESI mode. The validation data ful- filled the requirements of the European SANTE/11945/2015 Guideline. The specificity of the developed method is consid- ered satisfactory. Good linearity (R 2 > 0.99) was obtained for all pesticide matrix calibration curves within the range of 0.1– 100 μg kg -1 . Mean recoveries of all target analytes ranged from 80.4 to 117.3%, and limits of quantification (LOQ) ranged from 1.1 to 13.1 μg kg -1 , depending on pesticide res- idues. The repeatability and within-laboratory reproducibility ranged from 0.2 to 15.1% and from 1.3 to 19.4%, respectively. The uncertainty was not higher than 48% for target analytes in the three matrices. The validated method was successfully applied to screening of milk and milk products, and none of the 167 pesticides investigated was detected in 92 real samples. Keywords Pesticides . LC-MS/MS . Method validation . Milk and milk products Introduction Pesticides are a very large and diverse group of substances, which are widely used in most sectors of the agricultural produc- tion to control and inhibit pests, such as insects, rodents, other plants (weeds), fungi or nematodes that can threaten human health and economy (Fenik et al. 2011). While there are many different registered formulations in liquid, solid or gaseous forms, the most commonly used pesticides on food crops are insecti- cides, fungicides and herbicides (Hotchkiss 1992; De et al. 2014). Although pesticides play a key role in crop protection, preservation of food and feed materials and prevention of vector- borne diseases caused by pathogens and parasites such as malar- ia, dengue, leishmaniasis and Japanese encephalitis, their exces- sive use has a deleterious effect on human health and the envi- ronment (Fenik et al. 2011). Pesticide residues are potentially toxic to aquatic and terrestrial organisms and have been associ- ated with several human health problems, ranging from short- term impacts such as headaches and nausea to chronic diseases like cancer, reproductive harm and endocrine disruption, depend- ing on the intrinsic characteristics of their active substances and use patterns (Berrada et al. 2010; Park et al. 2011). While avail- able data are inadequate to measure accurately the global health impacts of highly hazardous pesticides, the global impact of self- poisoning from preventable pesticide ingestion was estimated to amount to 186,000 deaths and 4,420,000 disability-adjusted life years in 2002 (WHO 2010). The development and validation of sensitive and selective multiresidue analytical methods are of great importance to satisfy the demand for monitoring pesticide residues at low concentration levels (e.g. at the μg kg -1 level) in various ag- ricultural and animal products (Chen et al. 2013). The key procedure of determination of pesticides is clean-up of sample extracts to avoid interferences from high complexity of the matrices such as fatty food matrices (Zhao et al. 2014). The * Bulent Kabak bulentkabak@hitit.edu.tr 1 Ministry of Food, Agriculture and Livestock, General Directorate of Food and Control, Food Control Laboratory, Adana, Turkey 2 Faculty of Engineering, Department of Food Engineering, Hitit University, 19030 Corum, Turkey Food Anal. Methods https://doi.org/10.1007/s12161-017-1066-0