Magnetic silicon carbide nanocomposite as a sorbent in magnetic dispersive solid phase extraction followed by dispersive liquid-liquid microextraction in the gas chromatographic determination of pesticides

A magnetic silicon carbide nanocomposite based-magnetic dispersive solid phase extraction approach using aspiration/dispersion cycles was proposed. Several pesticides including diazinon, ametryn, chlorpyrifos, hexaconazole, diniconazole, tebuconazole, and triticonazole were extracted by this method from different samples. The analytes were extracted by a few mg of the prepared nanocomposite from the sample solution. The sample solution and adsorbent contact area was increased by performing aspiration/dispersion cycles. The nanocomposite particles were separated from sample solution using a neodymium magnet. Then an appropriate volume of an organic solvent was added onto the nanocomposite particles to desorb the analytes. Then, the obtained eluate was utilized in the next microextraction method to achieve high sensitivity and enrichment factor. Gas chromatography equipped with mass spectrometry was used for determination of the extracted analytes. Validation values considering ICH protocol illustrated that limits of detection and quantification were within the ranges of 0.06-0.33 and 0.19-1.0 ng mL(-1). Good precision (relative standard deviations <= 7.0 %), acceptable linearity (r(2) >= 0.992), high enrichment factors (600-850), extensive linear ranges, and acceptable extraction recoveries (60-85 %) were obtained. This approach was done on different real samples and chlorpyrifos and diazinon were determined in some of them.