Customized dispersive micro-solid-phase extraction device combined with micro-desorption for the simultaneous determination of 39 multiclass pesticides in environmental water samples

A dispersive micro-solid phase extraction (d-mu-SPE) procedure was developed for the simultaneous extraction of 39 multiclass pesticides, containing a variety of chemical groups (organophosphate, organochlorine, pyrethroid, strobilurin, thiocarbamate, triazole, imidazole, and triazine), from water samples. A customized d-mu-SPE glass device was combined with a multi-tube platform vortex and a micro-desorption unit (Whatman Mini-UniPrep G2 syringeless filter), which allowed the unique simultaneous desorption, extract filtration, and injection. A simplex-centroid mixture design and Doehlert design were employed to optimize the extraction conditions. The optimized extraction conditions consisted of an extraction time of 30 min, an addition of 6.74 % of NaCl into 100 mL of water sample, and a desorption time of 24 min with 500 mu L of EtAc. The procedure provided a low limit of detection (LOD), ranging from 0.51 ng L-1 (4,4-DDE) to 22.4 ng L-1 (dimethoate), and an enrichment factor ranging from 72.5 (dimethoate) to 200 (tebuconazole). The relative recoveries of the pesticides from spiked freshwater and seawater ranged from 74.2 % (endrin) to 123 % (molinate). The proposed procedure was applied to detect the presence of multiclass pesticides in environmental water samples. Three pesticides commonly applied in Brazil, namely, malathion, dimethoate, and lambda-cyhalothrin, were detected in concentrations ranging from

Automated summary

A new dispersive micro-solid phase extraction method was developed for the simultaneous extraction of multiple classes of pesticides from water samples, with low detection limits and high enrichment factors, suitable for pesticide detection in environmental water samples.