Homogeneous Liquid–Liquid Microextraction for Determination of Organochlorine Pesticides in Water and Fruit Samples

Ternary solvent based homogeneous liquid-liquid microextraction for the preconcentration of organochlorine pesticides from water and apple juice samples

In the present study, the optimal experimental conditions were determined by optimizing the effect of extraction solvent types and volume, salt types and concentration, centrifugation speed and time using one variable at a time. Under optimal experimental conditions, calibration curves were constructed separately using water and apple juice samples as representative matrices, and good linearities were achieved over a wide concentration range of 0.2-1600 ng L-1 with a coefficient of determination (r2) ≥ 0.998. The limits of detection (LOD) and limits of quantification (LOQ), determined to be 3 and 10 times the signal-to-noise ratios (S/N), were between 0.07-3.9 and 0.2-12.0 ng L-1 for water samples and 2.6-10.0 and 8.0-30.0 ng L-1 for the apple juice sample respectively. The precisions study showed %RSD values of ≤6% for both matrices, indicating satisfactory precisions. The enrichment factors and recoveries of the proposed method ranged from 41.4-74.5 and 86-109% respectively. The proposed method could be used as a simple and environmentally friendly alternative for the analysis of OCPs from environmental and food matrices. This method potentially offers a more sustainable and effective approach to monitoring OCPs in environmental and food products. Its use in the analysis of apple juice samples is particularly novel and can provide valuable insights into pesticide contamination in fruit juices.

Effervescent powder-assisted floating organic solvent-based dispersive liquid-liquid microextraction for determination of organochlorine pesticides in water by GC-MS

An effervescent powder-assisted floating organic solvent-based dispersive liquid-liquid microextraction was introduced for determination of 13 organochlorine pesticides in water samples. In this method, a less toxic low-density organic solvent was used as extraction solvent. The extraction solvent was dispersed in to the aqueous sample via CO₂ bubbles, in-situ generated up on addition of water to a falcon tube containing the mixture of effervescent powder precursors as well as the extraction solvent. Various experimental parameters such as effervescent and its weight fractions, extraction solvent type and its volume, the total mass of effervescent precursors, and the effect of salt were investigated and the optimal conditions were established. Under the optimum conditions, the proposed method exhibited good linearity for all target pesticides with the coefficient of determinations varying from 0.9981 to 0.9997. The limits of detection and quantification were within the range of 0.03-0.24 and 0.26-0.75 μg/L, respectively. The intra- and inter-day precisions which were expressed in terms of the relative standard deviation ranged from 0.33 to 4.47 and 0.51-5.52%, respectively. The enrichment factors and recoveries ranged from 24 to 293 and 76-116%, respectively. The proposed method could be used simple, cheap, fast, and environmentally friendly alternative for analysis of organochlorine pesticides from environmental water and other similar matrices.

Organochlorine pesticide residues in agricultural draining water in Tunisia

Organochlorines pesticides (OCPs) are persistent organic pollutants known by their persistence, their ability to bioaccumulate in the food chain and by their toxicity. This work aims to analyze pesticides in draining water samples taken from two different regions from Tunisia. A liquid-liquid extraction method proposed by the International Atomic Energy Agency (IAEA) has been adopted for the extraction of OCPs from draining water. The analysis of these compounds was carried out with a gas chromatography coupled to mass spectrometry. Eight draining water sample was analyzed from the region of Kebili and levels of OCPs ranged between ND and 3.415 ng L^-1. Four draining water samples were sampled from the region of Cap Bon and levels of OCPs in draining water varied between 14.955 and 59.305 ng L^-1. The concentration of OCPs in draining water didn't exceed the limits standardized by the regulations for drainage water, which makes possible the reuse of this water for agricultural purposes after having undergone a secondary treatment.

Development of effervescence-assisted switchable-polarity solvent homogeneous liquid-phase microextraction for the determination of permethrin and deltamethrin in water samples prior to GC-FID

An effervescent tablet-assisted switchable polarity solvent-based homogeneous liquid-phase microextraction (ETA-SPS-HLPME) combined with gas chromatography with flame ionization detection has been conducted for the separation, preconcentration, and detection of permethrin and deltamethrin in the river water specimens. The triethylamine (TEA) was utilized as a switchable polarity solvent in this method. The switching process was carried out by the dissolution of an effervescent tablet including an effervescency agent (sodium carbonate) and a proton donor agent (citric acid). Changing the pH of the specimen solution enhanced the conversion of TEA into protonated triethylamine carbonate (P-TEA-C) through the tablet that generated carbon dioxide (CO₂ ) bubbles in situ. Finally, the addition of sodium hydroxide changed the ionization state of TEA and separated two phases. Influential factors in extraction were investigated. According to optimal situations, the limits of detection (LOD) and the limits of quantification (LOQ) were obtained 0.16 and 0.5 μgL^-1 for permethrin and 0.03 and 0.1 μgL^-1 for deltamethrin respectively. The preconcentration factor (PF) was achieved 194 in river water samples and interday and intraday precision (RSD % n = 5) was <5%. The extraction recovery was obtained in the range of 93.0-97% for permethrin and deltamethrin in water samples.

Deep eutectic solvent dependent carbon dioxide switching as a homogeneous extracting solvent in liquid-liquid microextraction

A miscible-immiscible deep eutectic solvent (DES) containing monoethanolamine/4-methoxyphenol was used as an extraction solvent in a homogeneous liquid-liquid microextraction (HLLME). The method was used to preconcentrate chlorobenzenes in water samples followed by separating and analyzing them by gas chromatography-mass spectroscopy (GC-MS). A special feature of the new extraction method is that a green miscible solvent was used as an extractant in the HLLME method. The developed extraction technique provided enrichment factors in the range of 13.1-42.1 for extraction from only 1.0 mL of the aqueous sample solution. The effects of various experimental parameters were investigated and optimized. The optimal conditions were as follows: vortex time: 30.0 s, bubbling CO₂ gas: 1.0 min, salt concentration: 5.0% w/v, rate and time of centrifuge: 4000.0 rpm and 3.0 min, respectively, and DES volume: 30.0 µL. The limit of detections and the limit of quantifications for the four targeted analytes varied from 0.01-0.15 and 0.025-0.5 µg L^-1, respectively. The precision and long-term precision tests for the developed method were found to be less than 11.0%. Two real samples, including toilet air freshener and car perfume, were analyzed. The applied DES in the HLLME method provides a fast means of sample preparation for environmental aqueous sample solutions.

Multi-Residue Screening of Pesticides in Aquaculture Waters through Ultra-High-Performance Liquid Chromatography-Q/Orbitrap Mass Spectrometry

Pesticide residues in foodstuffs can lead to several undesirable effects. A simple and high-throughput targeted screening method analyzing multi-residue pesticide in aquaculture water based on ultra-high-performance liquid chromatography-Q/Orbitrap mass spectrometry (UHPLC-Q/Orbi MS) was developed and validated. In this technique, the peaks of the compound using precursor ions were recorded by the full scan, which was used for rough quantitative analysis with single point matrix matched calibration. The qualitative identification was performed following the stringent confirmation criteria with fragment ions, retention time, and an isotopic pattern. Additionally, solid-phase extraction with an HLB (Hydrophilic/Lipophilic Balanced) column was selected to enrich and separate target pesticides from water. The screening detection limit of 33 compounds are less than 2 ng·L−1, while 26 compounds range from 2 ng·L−1 to 10 ng·L−1, 19 compounds are at the range of 10–200 ng·L−1, and the other two compounds are 200 ng·L−1 and 1000 ng·L−1. Most of the recovery results were found to be between 60~130%. Finally, the method was successfully applied to the analysis of pesticide residues in 30 water samples from aquaculture environment in Shanghai, indicating its applicability in pesticide screening for environmental monitoring.

Control of Organophosphorus Pesticides Residues in Honey Samples Using a Miniaturized Tandem Preconcentration Technique Coupled with High Performance Liquid Chromatography

Background : In the present work, a miniaturized sample preparation method based on combination of dispersive solid phase extraction and temperature–induced homogenous liquid–liquid microextraction has been proposed for the extraction and preconcentration of some organophosphorus pesticides (parathion–methyl, triazophos, parathion, diazinon, and phoxim) from honey samples prior to their analysis by high performance liquid chromatography–ultraviolet detection. Methods: In this method, initially the analytes were adsorbed onto a sorbent (C18) and then desorbed by the use of cyclohexyl amine as an eluent. In the next step, the eluent was mixed with water thermostated at 0 °C to obtain a homogenous solution. By increasing the temperature, the solubility of cyclohexyl amine in water was decreased and led to formation of dispersed fine droplets in the whole of solution. These droplets go up through the solution and collected on top of the solution. Finally, an aliquot of the organic phase was sucked in a microsyringe and injected into the separation system for analysis. Results: Under the optimum experimental conditions, limits of detection and quantification were calculated to be in the ranges of 0.90–1.75 and 3.0–5.8 ng g–1 in honey samples, respectively. Enrichment factors and extraction recoveries were in the ranges of 148–183 and 59–73%, respectively. The relative standard deviations varied from 2–4% and 4–5% for intra– (n = 6) and inter–day (n = 4) precisions, respectively. Conclusion: The suggested approach was satisfactorily utilized to the analysis of 21 honey samples. The proposed miniaturized tandem sample pretreatment method enhanced the sensitivity of the instrumental analysis.

Validating Analytical Protocols to Determine Selected Pesticides and PCBs Using Routine Samples

This study aims at providing recommendations concerning the validation of analytical protocols by using routine samples. It is intended to provide a case-study on how to validate the analytical methods in different environmental matrices. In order to analyze the selected compounds (pesticides and polychlorinated biphenyls) in two different environmental matrices, the current work has performed and validated two analytical procedures by GC-MS. A description is given of the validation of the two protocols by the analysis of more than 30 samples of water and sediments collected along nine months. The present work also scopes the uncertainty associated with both analytical protocols. In detail, uncertainty of water sample was performed through a conventional approach. However, for the sediments matrices, the estimation of proportional/constant bias is also included due to its inhomogeneity. Results for the sediment matrix are reliable, showing a range 25-35% of analytical variability associated with intermediate conditions. The analytical methodology for the water matrix determines the selected compounds with acceptable recoveries and the combined uncertainty ranges between 20 and 30%. Analyzing routine samples is rarely applied to assess trueness of novel analytical methods and up to now this methodology was not focused on organochlorine compounds in environmental matrices.