Cloud point extraction and gas chromatography with direct microvial insert thermal desorption for the determination of haloanisoles in alcoholic beverages

Facile Cloud Point Extraction for the Separation and Determination of Phenolic Acids from Dandelion

It is significantly crucial to develop a robust pretreatment for the quantitative analysis of herbs. However, the traditional strategies are time-consuming, tedious, and not eco-friendly. In this work, cloud point extraction (CPE) is engineered for the simultaneous separation and enrichment of ferulic acid (FA), chlorogenic acid (CLA), and caffeic acid (CA) from dandelion prior to its determination by high-performance liquid chromatography (HPLC). A famous nonionic surfactant of Triton X-114 was selected as an extractant of CPE, and parameters affecting the extraction, such as surfactant concentration, salt content, pH value, temperature, and incubation time, were investigated carefully. Furthermore, the well-designed CPE with ultrasonic assistance combined with HPLC was developed for the detection of the target analytes in dandelion. The established method having a good linearity in the range of 0.15-26.2 mg L-1 with R 2 more than 0.9979 and the spiked recoveries ranging from 81 to 96% was applied to test real samples of dandelion. The contents of CA in samples were consistent with those assayed by the method (Chinese Pharmacopoeia 2015). The proposed method afforded good analytical performances, shorter pretreatment time (65 min), and less organic solvent consumption (less than 1.0 mL). It was proved that the developed method presented a facile, inexpensive, efficient, and environment-friendly pretreatment and can be used for the quantitative analysis of CLA, CA, and FA in dandelion. As expected, the proposed method would be a promising potential for the quality analysis of herbal medicines.

Combination of solvent extraction with deep eutectic solvent based dispersive liquid-liquid microextraction for the analysis of aflatoxin M1 in cheese samples using response surface methodology optimization

A new extraction procedure based on combination of a solvent extraction and deep eutectic solvent based dispersive liquid-liquid microextraction has been introduced for the extraction of aflatoxin M₁ from cheese samples. In this method, acetonitrile, deionized water, and n-hexane are added onto the sample and vortexed. Owning to different affinities of the substances in cheese toward the mentioned solvents, an efficient and selective extraction of the analyte is done in the acetonitrile phase. After centrifugation, the acetonitrile phase is removed and mixed with a new hydrophobic deep eutectic solvent prepared from N,N-diethanol ammonium chloride and carvacrol as an extraction solvent. The mixture is injected into deionized water, and a cloudy solution is obtained. Eventually, an aliquot of the organic phase is injected into high-performance liquid chromatography-fluorescence detection. After optimizing the effective parameters with the response surface methodology and a quadratic model, limits of detection and quantification were 0.74 and 2.56 ng/kg, respectively. The obtained extraction recovery and enrichment factor were 94% and 94, respectively. Also, intra- (n = 6) and interday (n = 4) precisions were less than or equal to 8.6% at a concentration of 5 ng/kg. The suggested method was applied to determine aflatoxin M₁ in different cheese samples.

Dispersive solid phase extraction combined with solidification of floating organic drop-liquid-liquid microextraction using in situ formation of deep eutectic solvent for extraction of phytosterols from edible oil samples

In this study, a dispersive solid phase extraction method was combined with solidification of floating organic drop-liquid-liquid microextraction based on in situ synthesis of deep eutectic solvent. It was used for the extraction of some phytosterols from edible oil samples. The extracted analytes were quantified by gas chromatography-mass spectrometry. In this procedure, the sample lipids are saponified with sodium hydroxide and then the analytes are adsorbed onto an octadecylsilane sorbent. After that the analytes are desorbed from the sorbent with ethanol as an elution solvent and the eluant is diluted with deionized water to obtain a homogenous solution. Then, a few amounts of choline chloride and n-butyric acid are dissolved in the solution and transferred into a water batch adjusted at 75 ⁰C for 5 min. During this period Choline chloride and n-butyric acid form a deep eutectic solvent (extraction solvent) dispersed in whole parts of the solution. The obtained cloudy solution is placed into an ice bath. The extraction solvent is collected and solidified on the top of the solution. Finally, it is removed and allows melted at room temperature and an aliquat of the solution is injected into the separation system. Validation of the method showed that limits of detection and quantification were in the ranges of 0.52-1.6 and 1.7-5.6 ng mL-1, respectively. Enrichment factors and extraction recoveries of the analytes ranged from 312 to 375 and 75-90%, respectively. The method had a proper percision with relative standard deviations less than ≤8.2% for intra- (n = 6) and inter-day (n = 6) precisions at a concentration of 15 ng mL-1 of each analyte. Finally the method was successfully used for determination of the analytes in some edible oil samples.

Twenty years of supramolecular solvents in sample preparation for chromatography: achievements and challenges ahead

Supramolecular solvents (SUPRAS) have progressively become a suitable alternative to organic solvents for sample preparation in chromatographic analysis. The inherent properties of these nanostructured solvents (e.g. different polarity microenvironments, multiple binding sites, possibility of tailoring their properties, etc.) offer multiple opportunities for the development of innovative sample treatment platforms not approachable by conventional solvents. In this review, major achievements attained in the combination SUPRAS-chromatography in the last 20 years as well as the challenges that should be addressed in the near future are critically discussed. Among achievements, particular attention is paid to the theoretical and practical knowledge gained that has helped make substantial progress in the area. In this respect, advances in the understanding of the mechanisms involved in SUPRAS formation and SUPRAS-solute interactions driving extractions are discussed, with a view to the setting up of knowledge-based extraction procedures. Likewise, the strategies followed to improve the compatibility of SUPRAS extracts with liquid and gas chromatography and adapt SUPRAS-based extractions to different formats are presented. Ongoing efforts to apply SUPRAS in multicomponent extractions and synthesize tailored SUPRAS for the development of innovative sample treatments are highlighted. Among challenges identified, discussion is focused on the automation of SUPRAS-based sample treatment and the elucidation of SUPRAS nanostructures, which are considered essential for their acceptance in routine labs and the design of tailored SUPRAS with programmed functions. Graphical abstract.

Microwave Assisted Cloud Point Extraction for the Determination of Vitamin K Homologues in Vegetables by Liquid Chromatography with Tandem Mass Spectrometry

Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) with a triple quadrupole (QqQ) is proposed for determining the vitamin K homologues, phylloquinone (PK), menaquinone-4 (MK) and menadione (MD), in vegetables. The analytes were isolated from the samples (1-1.5 g) by ultrasound assisted extraction using acetonitrile (2 mL), and the liquids were submitted to microwave assisted cloud point extraction with Triton X-45. The enrichment factors were between 20 and 50, depending on the vitamin homologue in question. The analytes were determined by LC-ESI-QqQ-MS/MS in the multiple reaction monitoring (MRM) mode, providing unequivocal identification and quantification, with limits of detection of 0.8, 1.0, and 16 ng/g for MK, PK, and MD, respectively. Recovery assays for samples spiked at two concentration levels, between 40 and 600 ng/g depending on the compound, provided recoveries in the 90-114% range. Only PK was detected in the samples analyzed, at concentrations in the 90-2350 ng/g range.