Determination of diflufenican and azaconazole pesticides in wastewater samples by GC-MS after preconcentration with stearic acid functionalized magnetic nanoparticles-based dispersive solid-phase extraction.

This study presents the preconcentration of diflufenican and azaconazole from domestic wastewater samples by using dispersive solid-phase extraction (dSPE) for determination by gas chromatography-mass spectrometry (GC-MS). Stearic acid-coated magnetic nanoparticles were used as adsorbents for dSPE method. In order to maximize the efficiency of the extraction process, parameters such as magnetic nanoparticle (MNP) type and amount, eluent type and volume, mixing type, and mixing period were all optimized. The linear range obtained for azaconazole and diflufenican was 7.50-500 ng/mL and 7.50-750 ng/mL, and their limits of detection/quantification (LOD/LOQ) were calculated as 1.3/4.3 ng/mL and 1.4/4.7 ng/mL, respectively. By comparing the LOD values of direct GC-MS and the developed dSPE method, azaconazole and diflufenican recorded approximately 35 and 38 folds enhancement in detection power. Recovery experiments with domestic wastewater were carried out to certify the proposed method's accuracy and applicability. By using the matrix matching calibration strategy, the good percent recovery results between 98 and 105% were obtained.

Development and validation of dispersive liquid-liquid microextraction method for the determination of 15 polycyclic aromatic hydrocarbons in 200 Antarctica samples by gas chromatography mass spectrometry.

Antarctica has seen an increase in scientific research and tourism, and anthropogenic activities such as incineration of waste products and fuel combustion for energy and transportation are potential contamination sources to the ecosystem. Polycyclic aromatic hydrocarbons are common products of incomplete combustion of organic compounds and could be among accumulating contaminants in Antarctica. Thus, this study sought to develop a sensitive dispersive liquid-liquid microextraction method for the determination of 15 polycyclic aromatic hydrocarbons by gas chromatography mass spectrometry. Parameters that were relevant to the extraction method were carefully optimized and validated using aqueous standard solutions. The optimum method recorded detection limits in the range of 0.20-6.1 µg/L for the analytes. Spike recovery experiments were carried out on artificial seawater, rock-soil, and moss samples, using matrix matching calibration to mitigate effects of the sample matrices. The samples analyzed included seawater, lake, rock-soil, moss, seaweed, and feces samples all collected from the Horseshoe and Faure Islands in Antarctica. The percent recovery results obtained for the samples spiked at different concentrations ranged between 86 and 115%.

A novel and rapid extraction protocol for sensitive and accurate determination of prochloraz in orange juice samples: Vortex-assisted spraying-based fine droplet formation liquid-phase microextraction before gas chromatography-mass spectrometry.

A novel, ecofriendly, and easy extraction and preconcentration method named as vortex-assisted spraying-based fine droplet formation liquid-phase microextraction was proposed for the determination of prochloraz at trace levels in orange juice samples by gas chromatography-mass spectrometry (GC-MS). In this novel system, extraction solvent is dispersed by the help of spraying apparatus instead of dispersive solvent. Various parameters of the method were carefully optimized to increase signal-to-noise ratio of the analyte. Under the optimum chromatographic and extraction conditions, limit of detection and limit of quantification were calculated as 3.2 and 10.8 µg/kg, respectively. Moreover, enhancement in quantification power for the GC-MS system was determined as 372 folds based on LOQ comparison. Relative recovery results for orange juice samples were found to be between 95.0-107.7% by utilizing matrix matching calibration. Furthermore, the developed method may be used to efficiently and simply extract other organic compounds for their determinations in several matrices.