Advances in Sample Preparation最新文献

Natural deep eutectic solvents (NADES) have emerged as promising green solvents, particularly useful in sample treatment procedures. For the first time, different types of NADES were prepared and evaluated as potential phenolic extraction solvents from tea samples (Camellia sinensis). The NADES, composed of lactic acid:glycerol:water in a molar ratio of 1:1:3, provided the best results for the simultaneous extraction of the target phenolic compounds. This NADES was also characterized by using nuclear magnetic resonance (NMR), and the presence of nuclear Overhauser enhancement effects confirmed its supramolecular structure. The experimental conditions affecting the miniaturized ultrasonic-assisted extraction (UAE) were optimized to maximize extraction efficiency by performing a design of experiments. The proposed sample treatment was combined with ultra-high performance liquid-chromatography coupled to tandem mass spectrometry detection (UHPLC-MS/MS) to determine 21 phenolic compounds including catechin derivatives and other minor compounds. The UAE-UHPLC-MS/MS method was successfully characterized and applied to the analysis of various commercial green, black, white and red tea samples. In all cases, 18 phenolic compounds were determined with concentrations ranging from 0.3 to 29,125 mg kg⁻¹. The proposed sample treatment is a high-throughput, easy, fast and robust alternative to conventional procedures, which reduces organic solvent consumption and costs, aligned with green sample preparation principles.

Asymmetric micro-electromembrane extraction (µ-EME) based on a free liquid membrane has been evaluated for the preconcentration of nanoplastics. A conical unit (200 µL micropipette tip) enabled the simple and reproducible formation of the required three-phase extraction system consisting of a donor solution (150 µL sample/standard solution), free liquid membrane (FLM; 10 µL 1-pentanol), and an acceptor solution (5 µL of 5 mM phosphate buffer, pH 10.7). After µ-EME, nanoplastics transferred across the FLM into the acceptor solution were quantified using capillary zone electrophoresis with diode array detection. Enrichment factors >20 and extraction recoveries >70 % were achieved for nanoplastics concentrated at 500 V during 5 min. The limit of detection (LOD, S/N = 3) and limit of quantification (LOQ, S/N = 10) of the method using 200 nm sulphonated polystyrene particles as model nanoplastics were 6.00×10⁻⁴% (w/v) and 2.00×10⁻³% (w/v), respectively. Intraday (n = 6) and interday (n = 6) repeatability%RSD for 5.5 × 10⁻³% (w/v) nanoplastics were 8.5 % and 7.2 %, respectively. µ-EME enabled an efficient sample matrix clean-up and preconcentration of nanoplastics spiked in tea sample matrices. Nanoplastics preconcentrated through the FLM for black tea resulted in an enrichment factor of 20±3.6 (n = 3), with complete sample matrix removal of UV absorbing compounds.

For the first time, we present targeted protein detection by tryptic digestion of human chorionic gonadotropin (hCG) followed by electromembrane extraction (EME). Operational parameters were optimized, and urine and serum samples spiked with hCG underwent tryptic digestion followed by EME of the βT5 signature peptide. The liquid membrane comprised nitrophenyl octyl ether (NPOE), carvacrol, and di(2-ethyl hexyl) phosphate (DEHP) at ratios of 49:49:2 (w/w/w). Extractions were performed in a conductive vial format for 45 min at 5 V. Even from highly complex digested samples of serum and urine, the signature peptide βT5 was extracted by EME and detected by LC-MS/MS. While attempts to extract intact hCG protein were unsuccessful, the extraction of the signature peptide was efficient. The extraction recovery from undigested and digested urine was 71 % (RSD = 17 %) and 116 % (RSD = 17 %), respectively. For serum, the extraction recoveries were 11 % (RSD = 23 %) for undigested samples and 110 % (RSD = 14 %) for digested samples. This study demonstrates both the potential and challenges of EME for protein analysis. Experiments regarding EME of intact proteins provided new insights into protein phase distribution. This fundamental case study underscores the potential of EME as a sample preparation technique for the targeted determination of protein biomarkers and drugs.

Analyzing fatty acids provides key insights into fat composition for industrial applications and their implications for nutrition and health. Typically, fatty acid analysis involves extracting lipids from the matrix and converting them into fatty acid methyl esters (FAME) through a derivatization process before gas chromatography (GC) analysis. Either one-step or two-step procedures can be found in the literature and as official methods. In this work, different methods exploiting microwave-assisted processes were compared with two official methods from the American Oil Chemical Society (AOCS). Especially, two types of microwave-assisted extractions were employed: solvent extraction and extraction with hydrolysis. The extracts were derivatized using either BF₃ or a microwave-assisted methanolic hydrogen chloride solution. These combinations of extraction and derivatization methods were compared also with one-step microwave-assisted extraction and derivatization, and two AOCS reference methods, resulting in seven different methods applied to six different food matrices. The performance of the different procedures was compared based on the FAME profile obtained from the comprehensive two-dimensional GC (GC × GC)-FID analysis.

Microwave-assisted processes were shown to be effective, yielding results comparable to the official methods in both the one-step and two-step methods. Moreover, it was shown that the BF₃ derivatization could be safely replaced with microwave-assisted derivatization with methanolic hydrogen chloride, providing equivalent performances while enhancing operator safety and environmental friendliness. Some discrepancies in the FAMEs profile were highlighted for the sample of oats, the only explicitly requiring acidic hydrolysis for lipid extraction. Further studies are required to understand the reasons behind these differences and develop a suitable modified method. In conclusion, all the methods were evaluated for greenness and blueness with two specific tools: AGREEprep and BAGI.

Vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) could provide an alternative for extracting pesticides from grape samples. Vac-HS-SPME method is utilized to the simultaneous analysis of six pesticides from various classes, namely boscalid, quizalofop-p-methyl, oxyfluorfen, fluroxypyr-meptyl, metribuzin and epoxiconazole. In this study investigated and optimized the impact of independent variables, such as extraction temperature, extraction time, fiber coating, incubation time, salt effect, sample volume, air evacuation time, pH, desorption time with the objective of achieving lower detection limits (ranging from 0.11 to 0.61 µg mL^-1) and effective analyte responses. Moreover, in this work a comparison was made between classical solid phase microextraction and vacuum-assisted solid phase microextraction for the extraction of pesticides in grape samples under the same parameters. The results clearly demonstrated that the combination of Vac-HS-SPME proved to be more appropriate and selective for the extraction of pesticides from grape samples.