Determining pyroxasulfone herbicide in honey samples using liquid-liquid extraction with low temperature purification (LLE-LTP).

Pyroxasulfone is a selective, systemic, pre-emergence herbicide which acts to inhibit weeds in potato, coffee, sugar cane, eucalyptus, and soybean plantations, among others. This active ingredient was classified by Brazilian legislation as a very dangerous product for the environment, and to date there are no studies involving the development of extraction methods for monitoring this compound in environmental matrices. Therefore, the objective of this study was to optimize and validate liquid-liquid extraction with low temperature purification followed by a gas chromatography coupled to mass spectrometry analysis to determine this herbicide in honey samples. The results showed that the best extractor phase was acetonitrile and ethyl acetate (6.5 mL:1.5 mL), with recovery rates close to 100% and relative standard deviations below 11%. The validation proved that the extraction method was selective, precise, accurate and linear in the range of 3-225 μg kg, reaching a limit of quantification of 3 μg kg, with a -25.95% matrix effect. Monitoring on real samples did not reveal episodes of environmental contamination with pyroxasulfone residue.