Green and simple analytical method to determine benzimidazoles in milk samples by using salting-out assisted liquid-liquid extraction and capillary liquid chromatography

Miniaturized liquid chromatography in environmental analysis. A review

The greater and more widespread use of chemicals, either from industry or daily use, is leading to an increase in the discharge of these substances into the environment. Some of these are known to be hazardous to humans and the environment and are regulated, but there is a large and increasing number of substances which pose a potential risk even at low concentration and are not controlled. In this context, new techniques and methodologies are being developed to deal with this concern. Miniaturized liquid chromatography (LC) emerges as a greener and more sensitive alternative to conventional LC. Furthermore, advances in instrument miniaturization have made possible the development of portable LC instrumentation which may become a promising tool for in-situ monitoring. This work reviews the environmental applications of miniaturized LC over the last 15 years and discusses the different instrumentation, including off- and on-line pretreatment techniques, chromatographic conditions, and contributions to the environmental knowledge.

Evaluation of a Chaotrope and Kosmotrope in the Multivariate Optimization of PHW-ATPE of Solasodine from Leaves of Solanum mauritianum

A hyphenated pressurized hot water—aqueous two-phase extraction (PHW-ATPE) method was applied to extract solasodine from Solanum mauritianum (S. mauritianum). A central composite design (CCD) was applied to determine the optimal conditions for the extraction of solasodine. The parameters evaluated included the percentage concentration of salt (NaCl or Na2CO3) and temperature. The fit of the central composite design response surface model for PHW-ATPE to the data generated a model with a good quadratic fit (R2 = 0.901). The statistically significant (p < 0.05) parameters, such as the linear and quadratic effects of the concentration of salt (%) powder, had a significant impact on the extraction of solasodine. The application of multiply charged salts such as Na2CO3 (kosmotrope) was shown to be a comparably better extractant of solasodine than NaCl (chaotrope) due to the salting-out effect. The optimized conditions for extraction of solasodine with NaCl or Na2CO3 were a temperature of 80 °C at a salt concentration of 20%. The maximum extraction of solasodine was 300.79 mg kg−1 and 162.34 mg kg−1 for Na2CO3 and NaCl, respectively.

Advanced microextraction techniques for the analysis of amphetamines in human breast milk and their comparison with conventional methods

Breast milk analysis provides useful information about acute newborn exposure to harmful substances, such as psychoactive drugs abused by a nursing mother. Since breast milk represents a complex matrix with large amounts of interfering compounds, a comprehensive sample pre-treatment is necessary. This work focuses on determination of amphetamines and synthetic cathinones in human breast milk by microextraction techniques (liquid-phase microextraction and electromembrane extraction), and their comparison to more conventional treatment methods (protein precipitation, liquid-liquid extraction, and salting-out assisted liquid-liquid extraction). The aim of this work was to optimize and validate all the extraction procedures and thoroughly assess their advantages and disadvantages with special regard to their routine clinical use. The applicability of the extractions was further verified by the analysis of six real samples collected from breastfeeding mothers suspected of amphetamine abuse. The membrane microextraction techniques turned out to be the most advantageous as they required low amounts of organic solvents but still provided efficient sample clean-up, excellent quantification limit (0.5 ng mL^-1), and good recovery (81-91% and 40-89% for electromembrane extraction and liquid-phase microextraction, respectively). The traditional liquid-liquid extraction as well as the salting-out assisted liquid-liquid extraction showed comparable recoveries (41-85% and 63-88%, respectively), but higher quantification limits (2.5 ng mL^-1 and 5 ng mL^-1, respectively). Moreover, these methods required multiple operating steps and were time consuming. Protein precipitation was fast and simple, but it demonstrated poor sample clean-up, low recovery (56-58%) and high quantification limit (5 ng mL^-1). Based on the overall results, microextraction methods can be considered promising candidates, even for routine laboratory use.

Determination of Levamisole and Mebendazole and Its Two Metabolite Residues in Three Poultry Species by HPLC-MS/MS

A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed to simultaneously analyze levamisole (LMS) and mebendazole (MBZ) and its two metabolites, 5-hydroxymebendazole (HMBZ) and 2-amino-5-benzoylbenzimidazole (AMBZ), in poultry muscle (chicken, duck and goose). In the sample preparation process, basic ethyl acetate was used as the extraction agent, and the extracted samples were back-extracted with hydrochloric acid, purified by Oasis MCX solid-phase extraction (SPE) cartridges, and reconstituted in the initial mobile phase after being blown dry with nitrogen. Chromatographic separation was performed on an Xbridge C₁₈ column (4.6 mm × 150 mm, 5 μm) with 0.1% formic acid in water and acetonitrile as the mobile phases, and gradient elution was performed at a flow rate of 0.6 mL/min and a column temperature of 35 °C. In blank poultry muscle samples, the spiked concentrations of LMS, MBZ, HMBZ, and AMBZ were within the range of the limit of quantitation (LOQ) to 25 μg/kg. The peak areas of the four target drugs had a good linear relationship with the concentration, and the determination coefficient (R²) values were higher than 0.9990. The average recoveries of LMS, MBZ, HMBZ, and AMBZ were 86.77–96.94%; the intraday relative standard deviations (RSDs) were 1.75–4.99% at LOQ, 0.5 maximum residue limit (MRL), 1.0 MRL, and 2.0 MRL; the interday RSDs were 2.54–5.52%; and the LODs and LOQs were 0.04–0.30 μg/kg and 0.12–0.80 μg/kg, respectively.

Pretreatment and determination methods for benzimidazoles: An update since 2005

Benzimidazoles, commonly used as pesticides and veterinary drugs, have posed a threat to human health and the environment due to unreasonable use and lack of valid regulation. Therefore, an up-to-date and comprehensive summary of the pretreatment and analytical approaches in different substrates is urgently needed. The present review consequently updates and covers various newly developed pretreatment methods (e.g., cationic micellar precipitation, magnetic-solid phase extraction, hollow fiber liquid phase microextraction, disperse liquid-liquid microextraction-solidified floating organic drop, stir cake sorptive extraction, solid phase microextraction method, QuEChERS, and molecular imprinted polymer-based methods) since 2005. The review also elaborates and discusses different determination methods (e.g., newly developed HPLC and related methods, improved spectrofluorimetry methods, capillary electrophoresis, and the electrochemical sensor). Furthermore, some critical points and prospects are highlighted, to describe the trends in this area.

Au@Ag-TGANPs based SERS for facile screening of thiabendazole and ferbam in liquid milk

Surface-enhanced Raman spectroscopy based on thioglycolic acid (TGA) functionalized silver-coated gold nanoparticles (Au@Ag-TGANPs) was developed for the facile screening of thiabendazole (TBZ) and ferbam (0.025-10 ppm) in liquid milk for the first time. Results showed that silver-coated gold nanoparticles (Au@AgNPs) with a core size of 32 nm and a shell thickness of 5 nm was successfully modified with 3 nm TGA. The sensitive Au@Ag-TGANPs could enhance TBZ and ferbam signals by factors of 6.4 × 10⁴ and 9.8 × 10⁴, respectively, and achieved the detection of TBZ and ferbam with limits of detection of 0.12 and 0.003 ppm, R² of 0.988 and 0.9821, percent recoveries of 88-103% and of 87.2-103.5%, and relative standard deviations of 4.1-9.2% and 3.5-8.3%, respectively. The current simple and green method could thus be used to detect other unsafe chemicals in future studies.

Novel Salt-Assisted Liquid-Liquid Microextraction Technique for Environmental, Food, and Biological Samples Analysis Applications: A Review

Background::

Sample preparation has gained significant recognition in the chemical analysis workflow. Substantial efforts have been made to simplify the comprehensive process of sample preparation that is focused on green sample preparation methodology, including the miniaturization of extraction method, elimination of the sample pre-treatment as well as the post-treatment steps, elimination of toxic as well as hazardous organic solvent consumption, reduction in sample volume requirements, reducing the extraction time, maximization of the extraction efficiency and possible automation.

Methods::

Among various microextraction processes, liquid-phase microextraction (LPME) is most abundantly used in the extraction of the target analytes. The salting-out phenomenon has been introduced into the LPME procedure and has been raised as a new technique called the ‘Salt-Assisted Liquid-Liquid Microextraction (SALLME)’. The principle is based on decreasing the solubility of less polar solvent or analyte with an increase in the concentration of the salt in aqueous solution leading to two-phase separation.

Conclusion::

SALLME proved to be a simple, rapid, and cost-effective sample preparation technique for the efficient extraction and preconcentration of organic and inorganic contaminants from various sample matrices, including environmental, biological, and food samples. SALLME exhibits higher extraction efficiency and recovery and compatible with multiple analytical instruments. This review provides an overview of developments in SALLME technique and its applications to till date.

A micro salting-out assisted liquid-liquid extraction combined with ultra-high performance liquid chromatography tandem mass spectrometry to determine anandamide and 2-arachidonoylglycerol in rat brain samples

A simple and reliable method was developed and validated to determine the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in rat brain samples by micro salting-out assisted liquid-liquid extraction combined with ultra-high performance liquid chromatography tandem mass spectrometry (SALLLE/UHPLC-MS/MS). The SALLE parameters (brain homogenate volume, salting-out agent, salt concentration, salt solution volume, organic solvent, organic solvent volume, and centrifugation temperature) were optimized to improve sensitivity and selectivity of the method. The SALLE/UHPLC-MS/MS method presented linear ranges from 2.00 to 20.00 ng mL^-1 for AEA and from 0.300 to 10.00 μg mL^-1 for 2-AG, no significant matrix effect, and inter- and intra-assay precision and accuracy with CV and RSE values lower than 15%, respectively. This innovative method was successfully applied to determine AEA and 2-AG in brain hemispheres from a 6-OHDA animal model of Parkinson's disease (PD).

Miniaturized liquid chromatography applied to the analysis of residues and contaminants in food: A review

The humankind is pretty dependent on food to control several biological processes into the organism. As the world population increases, the demand for foodstuffs follows the same trend claiming for a high food production situation. For this reason, a substantial amount of chemicals is used in agriculture and livestock husbandries every year, enhancing the likelihood of contaminated foodstuffs being commercialized. This outlook becomes a public health concern; thus, the governmental regulatory agencies impose laws to control the residues and contaminants in food matrices. Currently, one of the most important analytical techniques to perform it is LC. Despite its already recognized effectiveness, it is often time consuming and requires significant volumes of reagents, which are transformed into toxic waste. In this context, miniaturized LC modes emerge as a greener and more effective analytical technique. They have remarkable advantages, including higher sensitivity, lower sample amount, solvent and stationary phase requirements, and more natural coupling to MS. In this review, most of the critical characteristics of them are discussed, focusing on the benchtop instruments and their related analytical columns. Additionally, a discussion regarding the last 10 years of publications reporting miniaturized LC application for the analysis of natural and industrial food samples is categorized. The main chemical classes as applied in the crops are highlighted, including pesticides, veterinary drugs, and mycotoxins.

Salt-assisted liquid-liquid extraction in microchannel

In this study, for the first time, salt-assisted liquid-liquid extraction was performed in a microchannel system. The proposed design is based on the increase of contact surface area between target analytes and extracting phase during the sample and extracting phase transfer in microchannel. In this method, first sample solution, extracting solvent, and salt were mixed by stirrer and simultaneously delivered into a microchannel using a syringe pump. In order to optimize the influential parameters on the extraction efficiency of the proposed method, zidovudine and tenofovir disoproxil fumarate were selected as model analytes. The main parameters such as extracting solvent and its volume, salt amount, pH of sample solution, and microchannel shape, length, and its inner diameter were investigated and optimized. Under the optimized conditions, the proposed method was linear in the range of 0.1-30 µg/mL and R² coefficients were equal to 0.9922 and 0.9947 for zidovudine and tenofovir disoproxil fumarate, respectively. Extraction efficiency of the proposed method was compared with conventional salt-assisted liquid-liquid extraction. The results show that the proposed design has higher extraction efficiency than conventional salt-assisted liquid-liquid extraction. Finally, the proposed method was successfully applied for the determination of zidovudine and tenofovir disoproxil fumarate in plasma samples.

Total determination of triclabendazole and its metabolites in bovine tissues using liquid chromatography-tandem mass spectrometry

A reliable LC-MS/MS analytical method for the determination of residual triclabendazole and its principal metabolites (triclabendazole sulfoxide, triclabendazole sulfone and keto-triclabendazole) in bovine tissues was developed, in which triclabendazole and its metabolites are oxidized to keto-triclabendazole as a marker residue. The method involves sample digestion with hot sodium hydroxide, thus releasing the bound residues of various triclabendazole metabolites in bovine tissues. The target compounds are extracted from the digest mixture with ethyl acetate, defatted by liquid-liquid partitioning using n-hexane and acetonitrile, then oxidized with hydrogen peroxide in a mixture of ethanol and acetic acid. The reaction mixture is cleaned up using a strong cation exchange cartridge (Oasis MCX) and the analytes are quantified using LC-MS/MS. The optimal conditions for the complete oxidation of triclabendazole and its metabolites to keto-triclabendazole are an incubation time of 16 h and a temperature of 90 °C. The developed method was evaluated using three bovine samples: muscle, fat, and liver. Samples were spiked with triclabendazole and its principal metabolites at 0.01 mg/kg and at the Japanese Maximum Residue Limits (MRLs) established for each sample. The validation results show excellent recoveries (81-102%) and precision (<10%) for all target compounds. The limit of quantification (S/N ≥ 10) of the developed method is 0.01 mg/kg. These results suggest the developed method is applicable to quantifying residual triclabendazole in bovine tissues in compliance with the MRLs established by the Codex Alimentarius and EU and Japanese regulations, and thus the proposed method will be a useful tool for the regulatory monitoring of residual triclabendazole and its metabolites.