Advances in Sample Preparation最新文献

In this work, a microwave-assisted ultraviolet wet digestion (MAWD-UV) protocol was used to digest polymer-based materials (e-waste, food packing, medical-care materials, and individual protection equipment) for further halogen determination. Digests were suitable for Cl, Br, and I determination by inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma optical emission spectrometry (ICP-OES). Fluorine determination was performed with ion selective electrode (ISE). The power radiation and the digestion solution were evaluated. The accuracy was evaluated by comparing the results with those obtained after neutron activation analysis (NAA) for Cl and Br or using microwave-induced combustion (MIC) as sample preparation for F and I. Two certified reference materials (CRM) of low-density polyethylene (ERM EC680k and EC681k) were evaluated, and no differences were observed (t-test, 95% confidence level) between the results and the certified values. Quantitative recoveries for Cl, Br, and I were obtained using 200 mg of the sample using diluted acid solution (15 mL of 0.5 mol L⁻¹ HNO₃ plus 10.6 mol L⁻¹ of H₂O₂), with a 40 min radiation program (700 W, 25 min ramp). No statistical differences (ANOVA, 95% confidence level) were observed between the MAWD-UV and ICP-MS results and the reference values for Cl, Br, and I for several samples. However, results were lower than the reference values for fluorine, indicating that digestion efficiency was poor for this analyte, which was probably as an organic molecule (likely polytetrafluoroethylene). The limit of quantification (LOQ) was 0.216 mg g⁻¹ for Cl, 3.33 µg g⁻¹ for Br, and 0.036 µg g⁻¹ for I using ICP-MS. The main advantage of MAWD-UV is that it enables decomposing several polymer-based matrices using diluted acid without halogen losses. The developed method represents an important contribution to the digestion of these hard-to-digest matrices and in compliance with green analytical chemistry, thereby being an advance in sample preparation.

A simple and cost-effective analytical approach based on the combination of purge and trap technique coupling with smartphone-based image analysis was developed for the sensitive detection of ethanol. Herein, the dichromate solution was used as the detection reagent to determine the ethanol concentration in alcoholic beverages. The ethanol from the sample solution was purged by the airstream and then trapped into a 1-mL Eppendorf tube containing the detection reagent. During the process, ethanol is oxidized by dichromate reagent to form ethanoic acid, and the orange color of the dichromate ion is started to become darker after one minute. The color image of the Eppendorf tube was taken by smartphone in a controlled-light box and then analyzed by the laptop ImageJ software. Experimental parameters affecting the method sensitivity, such as extraction time, stirring rate, and dichromate concentration, were studied. Under the optimal conditions, the calibration curve was linear for the ethanol concentrations ranging from 0.15 and 3.0 %v/v (R² >0.993). The limit of detection of 0.05 %v/v was obtained. The intra- and inter-assay results (RSD%) were less than 1.0% and 2.0%, respectively. The developed approach has been successfully applied to determine ethanol percentage in beverage samples (alcoholic beer, brandy, and non-alcoholic beer), with relative recoveries ranging from 86-112%. Finally, the accuracy was assessed by comparison of the results obtained by our method and the UV-Vis spectrophotometric method, which agreed at the 95% confidence level.

A new method, based on the combination of two sorptive extraction methods, namely stir bar sorptive extraction (SBSE) and solvent-assisted stir bar sorptive extraction (SA-SBSE), was developed for the quantitative determination of ultra-trace levels of polyfunctional thiols in white wine. Extraction of 4-methyl-4-sulfanyl-pentan-2-one (4-MSP), 3-sulfanylhexan-1-ol (3-SH) and 2-furylmethanethiol (2-FMT) is performed by SA-SBSE combined with in-situ derivatization using ethylpropiolate (ETP), while 3-sulfanylhexyl acetate (3-SHA) is simultaneously extracted in parallel using SBSE, without derivatization. Analysis is performed by thermal desorption in combination with GC-MS/MS operated in selected reaction monitoring (SRM) mode. All four target solutes could be detected in a single GC-MS/MS run at levels below the odor detection threshold (ODT) of the solutes (LODs: 0.20 ng/L for 4-MSP, 2.8 ng/L for 3-SH, 0.27 ng/L for 3-SHA and 0.11 ng/L for 2-FMT). The method could be successfully applied to a set of white wine samples, showing significant differences in polyfunctional thiol concentrations between samples.

The quantification and interpretation of drug concentrations in biological matrices to optimize pharmacotherapy and to perform the therapeutic drug monitoring (TDM) is particularly important for compounds with narrow therapeutic ranges, known to cause adverse effects. In these cases, the biomonitoring is essential to avoid the toxicity and side effects. In this study, an innovative Fabric Phase Sorptive Extraction (FPSE) followed by high performance liquid chromatography-photodiode array detection (FPSE–HPLC–PDA) method was optimized and validated for the extraction and quantitative evaluation of seven antidepressant drugs (ADs, venlafaxine, citalopram, paroxetine, fluoxetine, sertraline, amitriptyline, and clomipramine) in human whole blood, urine, and saliva samples.

The best chromatographic separation was obtained using a reverse phase column and ammonium acetate (50 mM, pH 5.5) and acetonitrile (AcN) as mobile phases, with 0.3% of triethylamine (TEA) for the best peak shape. The used sample preparation technique, FPSE, developed in 2014, has offered numerous advantages such as low consumption of organic solvents, no sample pretreatment, and reduced overall sample preparation time. Among all tested membranes, sol-gel carbowax (CW 20 M) sorbent, coated on cellulose FPSE media, was the most efficient. The developed method provides satisfactory limit of detection of 0.06 μg/mL for all analytes except for venlafaxine that was 0.04 μg/mL. Both RSD% and BIAS% gave values below ±15%, according to current guidelines. Finally, real samples analyzes were carried out, comparing the obtained data with the anamnestic data of the subjects, confirmed the validity of the method.

Human exhaled breath contains various molecules that relate to human health and environmental exposures. There has been increasing interest in human breath analysis for exposure monitoring. This review focuses on the utilization of solid phase microextraction (SPME) for breath analysis of environmental and occupational exposures. Breath analysis of different types of exposures are summarized. The developments of SPME methods for breath analysis are highlighted. The limitations of the current studies and the prospects of breath analysis in exposure monitoring are discussed.

Solid-phase microextraction (SPME) has become a powerful sample preparation technique which allows to efficiently isolate and enrich analytes from complex matrixes. One of the most widespread SPME modes, consists of the extraction directly from the headspace (HS) which is equilibrated with the sample. In this sense, HS-SPME provides one of the best platforms for sample preparation, especially for the analysis of volatile and semi-volatile organic compounds. Furthermore, this technique has demonstrated to be versatile, sensitive, robust, and environmentally friendly when applied to samples coming from a diverse variety of fields such as bioanalysis, environmental sciences, food and cultural heritage. Moreover, during last years, the implementation of HS-SPME has dramatically grown along with the need to monitor complex systems over time using in situ and in vivo approaches, taking advantage of its noninvasive nature. In this review article, the authors present the fundamentals of this technique aiming to critically understand its advantages and limitations, highlighting the recent advances published in the last ten years. To this aim, special sections dealing with extractive phase development, technological advances and relevant applications in different fields have been carefully designed. Finally, some thoughts and perspectives about the future of the technique are also discussed.

For the first time, in-tube gel electro-membrane microextraction (IT-G-EME) system followed by microfluidic paper-based analytical devices (µPADs) as a low-cost reading platform was fabricated for the speciation of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) as model cationic and anionic compounds. In this new miniaturized extraction mode, a transparent narrow-bore polymeric tube was used as housing of the aqueous acceptor phase (AP, 30 µL), while an agarose gel membrane was placed as a micro plug (2.5 mm) at the beginning of the tube. A circular shape vial (1.5 mL, pH 5.5) containing chromium species as donor phase (DP) was connected between two tubes which previously filled with gel membrane and aqueous AP. By applying electric potential, the positively charged Cr(III) and negatively charged Cr(VI) in the DP migrated selectively toward cathodic and anodic tubes, respectively. After extraction, each AP was analyzed by µPAD, which had already been modified with diphenylcarbazide (DPC). Under the optimized extraction conditions, a good limit of detection (LOD) equal to 7.0 µg L^–1 was achieved for both analytes, while the extraction recoveries for Cr(VI) and Cr(III) were 72% and 84%. In addition, the developed approach was used for the quantification of chromium species in water samples.

This research was aimed at the development of the COMSOL Multiphysics® (CMP) model for simulating the headspace (HS) solid-phase microextraction (SPME) of volatile organic compounds (VOCs) from water using Carboxen/polydimethylsiloxane coating at 25 °C. The developed model is mainly based on existing theory and previous research on the numerical modeling of SPME. Fuller method was used to estimate diffusion coefficients in air as well as pores and voids of the coating. Coating-headspace distribution constants were estimated using linear solvation energy relationship (LSER) model and multiple regression obtained by Prikryl and Sevcik. Headspace-water constants were estimated using vapor pressures and activity coefficients were determined using UNIFAC model. Wilke and Chang method was chosen for estimating diffusion coefficients in water without stirring. Liss and Slater, and Southworth approaches were tested for estimating mass transfer coefficients at the headspace-water boundary under stirring. Southworth approach allowed obtaining benzene, toluene, ethylbenzene and o-xylene (BTEX) extraction profiles from water, which were closest to experimental profiles compared to other approaches. When using Southworth approach, root mean square deviation (RMSD) between experimental and simulated values for BTEX were 8.7–10% indicating the high accuracy of the model. The developed model was successfully applied for computational optimization of extraction parameters (stirring speed, fiber insertion depth, pressure, sample volume and the concentration of added salt). After minor modification, the model was also applied for optimization of preincubation time. It can be recommended for optimization of HSSPME-based analytical methods for VOCs quantification in water.