Determination of pesticide residues in milk using a QuEChERS-based method developed by response surface methodology

Response surface methodology (RSM) was employed to optimise a rapid and easy sample preparation method for the determination of 14 different pesticide residues in milk. The recovery of each pesticide was investigated by a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe)-based method with respect to 3 variables, the amounts of sodium acetate (Na Acetate), primary secondary amine (PSA), and octadecylsilane (C18). After optimisation, the maximum predicted recovery was the 99.73% rate for myclobutanil under the optimised conditions of 1.70 g Na Acetate, 600.00 mg PSA, and 489.96 mg C18. The recovery rates of the other 9 hydrophilic pesticides were ranged from 82.01% to 98.84%. However, the recovery rates for the 4 lipophilic pesticides (2,4'-DDE, 4,4'-DDE, 2,4'-DDT, and 4,4'-DDT) were <80% because they were removed by C18 along with the other fatty compounds. This method could be implemented in many laboratories to reduce inspection time and cost.