Advances in Sample Preparation最新文献

The quality by design (QbD) based approach has begun to be embedded in various method development. Studies show that with the design of experiment tool, the analysis process has become more efficient, faster, and easier. The analysis has two components: Method development and sample preparation. Sample preparation can be at least as difficult as method development, and sometimes even more difficult. Therefore, in addition to the new techniques and materials developed in sample preparation, the QbD approach can significantly reduce the workload of the analysts and provide analysis with high accuracy and precision. So far, very limited studies have been come across in the literature about the QbD approach. The review in question has been prepared to encourage and guide researchers on this subject, and will greatly support this deficiency.

The development of sample treatments based on supramolecular solvents (SUPRAS) has rapidly increased during the last decade. The reasons behind this interest are, among others, the need for more sustainable solvents, but above all, the demand for more efficient and fit-for-purpose sample treatments that face the current challenges confronted by analytical laboratories and some cutting-edge research areas. One of the most outstanding features of SUPRAS is their huge potential for designing ad-hoc sample treatments that solve specific analytical and operational issues. In this article, this potential is exemplified with the achievements obtained in two demanding areas: the screening/quantification of multiclass compounds and the development of matrix-independent analytical methods. We also highlight the need for development of knowledge-based tailoring of solvents that provide fit-for-purpose sample treatments in areas where current methodologies are not applicable or need better performance.

Two homemade silica-based mixed-mode ion-exchange sorbents with strong moieties were compared for the solid-phase extraction (SPE) of a group of pharmaceuticals, drugs of abuse and metabolites. The difference between sorbents was the presence of graphene microparticles embedded in the network and the best results were obtained with the sorbent that did not contain graphene.

The optimum SPE protocol of the non-graphene sorbent was: loading pH at 3, different loading volumes depending on the type of sample, 2 mL of MeOH as washing solvent.

The optimized method was validated for the analysis of water samples of environmental interest (river water, effluent wastewater and influent wastewater). Apparent recoveries ranged from 22 to 68%, matrix effect values were lower than ±20 for most compounds, and method detection limits ranged from 1 to 28 ng/L and method quantification limits from 2 to 56 ng/L. Precision was obtained as percentual relative standard deviation (RSD%, n=4) and the repeatability and reproducibility between days were always lower than 18%.

The sorbent was used to determine the analytes in environmental water samples, where most compounds were found in the range from 2 to 180 ng/L in river samples, from 3 to 2547 ng/L in effluent wastewater samples and from 24 to 8086 ng/L in influent wastewater samples.

A new and environmentally friendly analytical method for simultaneous determination of As, Cd, Hg and Pb in drug samples by inductively coupled plasma optical emission spectrometry (ICP OES) has been developed. In order to increase the sensitivity of the analysis, a multinebulizer has been used for chemical vapor generation (CVG) after a dispersive liquid-liquid microextraction (DLLME) procedure using a natural deep eutectic solvent (NADES) as extractant solvent. The factors affecting analyte extraction and on-line chemical vapor generation have been optimized by multivariate analysis. Under optimized conditions, DLLME-CVG-ICP OES improved limit of quantitation (LOQ) values on average 50-fold higher compared with direct ICP OES analysis and afforded an increase of the sensitivity (i.e., enrichment factor) on average 25-times higher than those obtained with CVG-ICP OES analysis. According to the United States Pharmacopoeia (USP) Chapter 232, it means LOQ values are on average 4.3-times lower than their respective 0.3J values for the target-elements from class 1. Trueness has been evaluated by recovery experiments following USP recommendations for two oral drug samples in solid dosage form (i.e., commercial dosage tablets). In addition, the greenness of the developed method has been evaluated using the AGREEprep metrics, showing an excellent green character since it includes the miniaturization of the sample preparation procedure using a reduced volume (i.e., few microliters) of a non-hazardous extractant solvent for multielemental analysis.

A green analytical method based on the use of a deep eutectic solvent (DES) has been proposed for fat removal in the analysis of polychlorinated biphenyl (PCBs) in biotic samples. Using priority PCB congeners as model compounds, a novel sample preparation approach fully avoiding the use of mineral acids has been developed. Once optimized, the procedure allowed fat removal to be accomplished by 30min treatment with [chlorine chloride]:[oxalic acid dihydrated] 1:1 molar ratio at 60°C, with 3s vortexing every 5min to facilitate the homogenization of the slurry. Then, the target PCBs were recovered from the slurry by 20min extraction with 4mL of n-hexane. This DES-based method was combined with gas chromatography-quadrupole mass spectrometry (GC-qMS) for final PCB determination. The complete analytical method provided satisfactory recoveries of the target compounds (above 87% for all analytes), using as a small amount of sample as 0.150g. The repeatability of the complete procedure, expressed as relative standard deviation, was less than 5%, and the intermediate precision better than 14%. Final validation of the proposed methodology included the satisfactory comparison of the concentrations calculated for the endogenous PCBs in selected fatty foodstuffs with lipid contents under 18% (w/w fresh weight, fw) with those found when the same samples were analyzed by a more conventional and accepted reference procedure. The limits of detection were in all cases lower than 30 pg/g fw (as calculated for real samples), demonstrating the feasibility of the proposed procedure for accurate determination of the target compounds in biotic samples.

Deep eutectic solvents (DES), and especially natural deep eutectic solvents (NADES), are advantageous alternatives over non-environmentally friendly organic solvents traditionally employed for sample preparation in analytical chemistry. Moreover, the use of DES has recently experienced remarkable growth to fulfill the green analytical chemistry principles. One of their most influential characteristics, which should be determined for each new DES, is viscosity. Manual or automatic viscometers are usually employed to this aim, but their use is sometimes hampered by characteristics of DES such as their variable water content or their wide viscosity range. In this study a proof-of-concept of the feasibility of employing a capillary electrophoresis (CE) instrument to determine this physicochemical property is shown. No change in the commercial instrument is required, and advantages such as applying controlled pressure and temperature, online UV detection at several wavelengths, use of extremely low volumes of solvents and viscosity markers, automation, etc., allow the easy and affordable adaptation of this method to different DES. As example of application, CE methods were used for viscosity measurement of ten different DES, including hydrophilic (based on either choline chloride or betaine) and hydrophobic ones (based on thymol), within two orders of magnitude (6 to 500 mPa⋅s). Agreement between the experimental results obtained with the CE instrument and data gathered by a commercial viscometer adequate for solvents without water or with published data (when available), is shown. Contribution of using DES to the green analytical chemistry principles is reinforced by the characterization for the first time of these solvents with the more sustainable and high applicability CE method here proposed.

A dispersive magnetic solid-phase extraction (DMPSE) procedure has been developed to preconcentrate four synthetic phosphodiesterase type 5 (PDE-5) inhibitors (sildenafil, desmethylsildenafil, vardenafil and tadalafil) from different samples (human hair, energy drinks, lubricating gels and dietary supplements). The target compounds were isolated from the solid samples by solid-liquid extraction in basic aqueous medium and the extract was submitted to DMSPE using multiwalled carbon nanotubes/Fe₃O₄@polypyrrole (MWCNTs/Fe₃O₄@PPy). For this, 20 mg of the magnetic nanocomposite was added to 30 mL of sample solution/extract and vortexed for 10 min before proceeding to the desorption step using 1 mL of methanol. Analysis was carried out by liquid chromatography with tandem mass spectrometry using electrospray ionization and a triple quadrupole mass analyzer (LC-ESI-QqQ-MS/MS). Matrix-matched calibration was applied for quantification. Limits of detection ranged between 0.01 and 0.22 ng mL⁻¹ for energy drinks and between 0.25 and 7.5 ng g⁻¹ for hair, lubricating gels, and dietary supplements. Relative standard deviations in the 4.3–12.2% (n = 10) were obtained for repeatability studies. The trueness of the proposed method was studied by fortifying the samples at two concentration levels and recoveries in the 85–112% range were obtained. None of the PDE-5 inhibitors studied were detected in real samples.

The steroid hormones in the aquatic environment have attracted widespread attentions due to their harmful effects to organisms. In order to improve the sensitivity and accuracy of steroid hormone detection, amphiphilic magnetic nanoparticles (AMNPs) were prepared through suspension copolymerization for microSPE of steroid hormones in water. The divinylbenzene and N-vinylpyrrolidone were selected as modified monomers, and Fe₃O₄ as the magnetic core. The FT-IR and SEM analyses showed that amphiphilic modified polymers were successfully coated on the surface of Fe₃O₄ magnetic beads. The hysteresis loop showed that the saturation magnetization value of obtained AMNPs was 36 emu·g⁻¹. In the adsorption test, the adsorption rate of nine steroid hormones by AMNPs can reach more than 90%. Based on this, an AMNPs-microSPE coupled with HPLC-MS/MS method was established to detect steroid hormones in the aquatic environment. The detection limit and quantitation limit of this analytical method was 0.01–0.72 μg·L⁻¹ and 0.10–2.4 μg·L⁻¹ respectively, with good linear fit and low relative standard deviation. The prepared AMNPs extraction materials show good recovery and reproducibility for steroid hormones in water, and have the advantages of low price, easy availability and reusable.

In this work, we have synthesized an iron based metal organic framework for removal of azo-dyes from textile industry wastewaters. The metal organic framework is comprised of two ligands, terephthalic acid and iminodiacetic acid chelated with iron. The chemical composition, surface morphology and diffraction pattern of the synthesized binary metal organic framework was confirmed with FT-IR, FE-SEM and XRD. Interaction with the model azo dye (methyl orange) has resulted in re-structuring of the native metal organic framework original shape (hexagonal nanorods to smaller octahedron structures). Under optimized conditions (time, and pH), the metal organic framework has a maximum methyl orange adsorption capacity of ∼ 280 mg per g. In presence of major salts as co-existing ions and two non-azo dyes, the methyl orange removal ability of metal organic framework significantly remained intact. The metal organic framework has displayed its practical applicability by efficiently removing two azo dyes (yellow and pink) from local textile industry wastewaters.