No abstract

A simple and rapid micellar electrokinetic capillary chromatography method of trifloxystrobin, tebufenozide, and halofenozide has been developed. The separation was performed in a 10 mM borate-18 mM SDS buffer solution (pH ¼ 9.0), containing 22.5% v/v of acetonitrile, 25 kV and detection at 202 nm. The linear concentration range of application was 0.5-10.0 mg L À1 , with a detection limit of 0.094 mg kg À1 for trifloxystrobin and 0.088 mg kg À1 for tebufenozide and halofenozide. Analysis yielded good reproducibility (RSD between 1.7-8.7%). The applicability of the method was tested by analyzing several fortified samples of tomato, celery, and apple juices. Recovery levels were between 70.0 and 110.8%.

An analytical method for the determination of diflufenican, mepanipyrim, pretilachlor, and fipronil in water samples was developed using single drop microextraction in the direct immersion mode and gas chromatography-mass spectrometry. A factorial fractionated design of type 2(6-1) at two levels was performed, to study the influence of experimental variables such as ionic strength, pH, agitation speed, extraction time, drop volume, and sample volume. To establish the optimal conditions for the variables that were significant, a Doehlert design was performed. The optimum conditions of extraction were 1 μL of heptane immersed in 4.0 mL of sample with continuous agitation at 500 rpm for 30 min at room temperature. The developed method proved to have good linearity for the range studied. The detection limits were 0.07 μg L(-1) for diflufenican, 0.03 μg L(-1) for mepanipyrim, 0.08 μg L(-1) for pretilachlor, and 1.39 μg L(-1) for fipronil. The method was validated on river water samples, showing the absence of matrix effect and recoveries ranged from 90.1 to 107.8 %. The results show that the method developed is accurate, sensitive, rapid, simple, and low cost, so it is recommended for application in the analysis of these different classes of pesticides in water samples.