Dispersive solid-phase extraction for the determination of trace organochlorine pesticides in apple juices using reduced graphene oxide coated with ZnO nanocomposites as sorbent

Graphene-based nanomaterials as potential candidates for environmental mitigation of pesticides

Over the years, bioaccumulation of hazardous chemicals in the food chain has become a critical issue, resulting in numerous health risks. Environmental mitigation aims to clean up contaminated sites and eliminate hazardous materials from the air, water, or soil to restore the site to its original and safe condition. Pesticides constitute one of the most dangerous environmental pollutants which are generally used to increase crop production. Addressing the removal or treatment of pesticides has become pivotal in mitigating environmental threats. Diverse remediation methods are employed to protect the environment and public health. Graphene-based materials have emerged as promising candidates with exceptional properties, including excellent adsorption capacity due to their high surface area, strong hydrophilicity, and tunable properties. Owing to these properties, they have been attracting major research attention in the field of design and fabrication of materials for the mitigation of pesticides from the environment such as from contaminated food, water and other samples. Various physical, chemical and biological extraction techniques are adopted to remove pesticides. This review article provides an insight into the potential role of graphene-based materials in the environmental remediation of pesticides. We have focused on the removal of Organophosphates, Organochlorines, Carbamates and Pyrethroids present in water, fruit, vegetable and other samples, highlighting the urgent need for environmental remediation. While graphene-based materials hold potential for pesticide remediation, addressing challenges in scalable production, assessing long-term sustainability, and mitigating potential environmental impacts are critical steps for successful large-scale applications.

Vortex-assisted dispersive micro-solid-phase extraction using silica-supported Fe2O3-modified khat (Catha edulis) biochar nanocomposite followed by GC-MS for the determination of organochlorine pesticides in juice samples

In this paper, dispersive micro-solid phase extraction technique was developed for the purpose of extracting and preconcentrating organochlorine pesticide residues in juice samples before their separation and quantitative analysis by gas chromatography-mass spectrometry. A sorbent composed of a silica-supported Fe2O3-modified khat leftover biochar nanocomposite (SiO2-Fe2O3-KLBNC) was implemented in the process. To improve the dispersion of the sorbent in the solution, vortex mixer was employed. Experimental parameters influencing the performance of the method were optimized, and the optimal conditions were established. With these conditions, linear dynamic ranges ranged from 0.003 to 100.0 ng/mL were achieved, with a correlation coefficient (r2) ≥ 0.9981. The limits of detection and quantification, determined by signal-to-noise ratios of 3 and 10, respectively, were found to be in the ranges of 0.001-0.006 ng/mL and 0.003-0.020 ng/mL. Intra- and inter-day precision, values ranging from 0.3-4.8% and 1.7-5.2% were obtained, respectively. The matrix-matched extraction recoveries demonstrated favorable outcomes, falling within the range of 83.4-108.3%. The utilization of khat leftover as an adsorbent in contemporary sample preparation methodologies offers a cost-effective alternative to the currently available, yet expensive, adsorbents. This renders it economically viable, particularly in resource-constrained regions, and is anticipated to witness widespread adoption in the coming future.

A convenient and effective method for determining organophosphorus pesticides in citrus fruits based on a novel dispersive solid phase extraction using UiO-66/Alg bead as the sorbent

This work presents a novel, convenient and effective method for assaying organophosphorus pesticides (OPPs) in the pulp and peel of citrus fruits. In this method, shaped UiO-66/alginate (UiO-66/Alg) beads were employed to replace the powder sorbents used in traditional dispersive solid phase extraction (d-SPE) methods. The UiO-66/Alg beads can be easily separated by only using a tweezer within 1 min, which effectively simplifies the sample pretreatment and overcomes the shortages brought by the incomplete separation of powder sorbents. Moreover, the matrix compounds can be effectively excluded by UiO-66/Alg beads, and the UiO-66/Alg beads can be reused at least 8 times. The d-SPE conditions were optimized by a single factor test. The method shows satisfactory sensitivity, accuracy and precision. Furthermore, ATR-FTIR and UV-Vis-DRS were employed to investigate the adsorption mechanism. Finally, the developed method was applied to monitor the OPPs in ten different citrus fruits.

Polycarbonate-coated magnetic nanoparticles for the extraction of imipramine and its primary metabolite from urine

This study introduces a reliable and inexpensive magnetic dispersive solid phase extraction to extract imipramine and its primary metabolite (desipramine) from urine samples. To accomplish this aim, Fe3 O4 magnetic nanoparticles were synthesized by sonication, subsequently, polycarbonate was precipitated gradually onto the surface of them to form the adsorbent. Extraction recoveries of 85% and 76%, enrichment factors of 57 and 51, limits of detection of 2.5 and 2.8 μg/L, and limits of quantification of 8.3 and 9.3 μg/L were obtained for imipramine and desipramine under the optimal conditions, respectively. In addition, relative standard deviations for intra- (n = 6) and inter-day (n = 5) precisions at two concentrations (50 and 100 μg/L of each analyte) were less than or equal to 4%. Short extraction time, good repeatability, high enrichment factors, and simplicity are the main advantages of the proposed method.

Solid-phase microextraction of eleven organochlorine pesticides from fruit and vegetable samples by a coated fiber with boron nitride modified multiwalled carbon nanotubes

A boron nitride modified multiwalled carbon nanotube material (BN@MWCNTs) was synthesized, and the synthesis conditions were optimized. The BN@MWCNTs was then used as the SPME fiber coating adsorbent for the extraction of eleven organochlorine pesticides (OCPs) from fruit and vegetable samples. Under the optimal conditions, the SPME coupled with the detection by GC-ECD had a linear response for the determination of the target analytes in the range of 0.03 to 200 ng g^-1 with the coefficients of determination (r²) ≥ 0.9977. Based on the signal-to-noise ratios of 3 and 10, the limits of detection and the limits of quantification were measured to be 0.01-0.20 ng g^-1 and 0.03-0.67 ng g^-1, respectively. The relative recoveries of the analytes for spiked samples under three concentration levels (1.0, 10.0 and 100 ng g^-1) were between 83.7% and 124% with the relative standard deviations ≤ 10.9%. The established method was successfully applied to the determination of OCPs in real fruit and vegetable samples.

Reduced graphene oxide-zinc oxide nanocomposite as dispersive solid-phase extraction sorbent for simultaneous enrichment and purification of multiple mycotoxins in Coptidis rhizoma (Huanglian) and analysis by liquid chromatography tandem mass spectrometry

In the current study, a robust dispersive solid-phase extraction (dSPE) strategy using reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposite as the sorbent was proposed for separation, purification and enrichment of 12 mycotoxins in Coptidis rhizoma (Huanglian). The targeted mycotoxins included aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, aflatoxin M1, alternariol-methylether, mycophenolic acid, ochratoxin A, penitrem A, nivalenol, zearalenone and zearalanone. The rGO-ZnO nanocomposite was successfully synthesized through hydrothermal process by a modified Hummers method, and further characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR spectroscopy, ultraviolet-visible spectroscopy and X-ray diffraction (XRD). Several key parameters affecting the performance of the dSPE approach were extensively investigated, and after optimization, acetonitrile/water/formic acid (80/19/1, v/v/v) as the extraction solution, 2% acetonitrile as the adsorption solution, 15 mg rGO-ZnO as the sorbent, n-hexane as the washing solution, and methanol/formic acid (99/1, v/v) as the desorption solution presented an excellent purification and enrichment efficiency. Under the optimal dSPE procedure followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), adequate linearity (R2 ≥ 0.991), high sensitivity (limit of quantification in the range of 0.09-0.41 µg kg-1), acceptable recovery (70.3-105.7%) and satisfactory precision (RSD 1.4-15.0%) were obtained. The analysis of 12 selected mycotoxins was also carried out in real Coptidis rhizoma (Huanglian) samples for applicability evaluation of the established method.