Low density miniaturized homogeneous liquid-liquid extraction: a new high throughput sample preparation technique for the determination of polar pesticides in cow milk

The application of miniaturized homogeneous liquid-liquid extraction (MHLLE) technique as a simple, inexpensive, quick and efficiency clean up method has been evaluated for determination of diazinon, alachlor, chlorpyrifos and butachlor in cow milk samples. Methanol was used as extraction solvent for the extraction of analytes from cow milk samples and then, methanol phase was extracted and cleaned up by MHLLE method. In this method, butyl acetate was added to methanol phase and after addition of water, butyl acetate was separated from methanol phase and injected to the GC/TSD instrument. The concentration ranges were from 1.0–1000.0 ng/mL for diazinon and chlorpyrifos and from 5.0–1000.0 ng/mL for alachlor and butachlor. The limits of detection were 0.4, 1.6, 0.3 and 1.4 ng/mL for diazinon, alachlor, chlorpyrifos and butachlor, respectively. Finally, the extraction method was successfully applied to the analysis of raw cow milk samples.