Mode Solid Phase Extraction Research Articles

Neodymium sorption on the Na-form of Transcarpathian clinoptilolite

The sorption properties of Na-modified Ukrainian Transcarpathian clinoptilolite towards neodymium aqueous solutions under dynamic conditions have been investigated. The sorption capacity of the Na-from of Transcarpathian clinoptilolite towards Nd(III) significantly depends on the concentration of neodymium salt, the pH of the solution, and the heat treatment temperature of the sorbent. Nd(III) is most efficiently sorbed from slightly alkaline solutions (pH 8.5), mainly by adsorption of neutral hydrolyzed forms of Nd(OH)3 on the surface of Na-clinoptilolite samples preheated at 75 °C. During the passage of an Nd(III) solution with a concentration of 1 μg mL−1 through the sorbent at a rate of 3 mL min−1 under optimal conditions, the sorption capacity of Na-clinoptilolite is 7.2 mg g−1, which is in 4 and 2.3 times higher than that of natural and acid-modified forms of this zeolite. It is shown that under the experimental conditions with an increase in the flow rate, the thickness of the stationary surface layer decreases, which leads to a decrease in the sorption capacity of Na-clinoptilolite. The best Nd(III) desorbents are solutions of mineral acids and acidified solutions of alkali metal salts (except NaCl), which provide 93–98 % extraction of lanthanide from the zeolite matrix. The method for neodymium trace amounts preconcentration from aqueous solutions in a solid-phase extraction mode with a further determination of this rare earth element by a spectrophotometric method was developed. The detection limit of this method is 0.75 ng mL−1 and the linearity was evaluated in the range of 2.5–500 ng mL−1.

Metal-organic frameworks as promising solid-phase sorbents for the isolation of third-generation synthetic cannabinoids in biological samples

In this work, metal-organic frameworks (MOFs) were used for the first time as solid-phase extraction (SPE) sorbents for the isolation of synthetic cannabinoids (SCs) from oral fluids and subsequently quantified by LC-fluorescence detection (FLD). In this context, different MOF families were synthesized and tested under SPE mode. UiO-66 was the family selected, being the amino functionalized (NH2-UiO-66) the best candidate in terms of extraction performance. After the method optimization, several analytical parameters of interest were obtained, reaching limits of detection (LODs) as low as 0.6–0.8 μg L−1 and precision values (expressed as RSD) lower than 10.6%. The developed method was successfully applied to the determination of 8 SCs in different oral fluids at three spiked levels with recoveries between 67 and 114%. This method claims to be a real alternative for screening purposes, being a cost-effective procedure due to the price of the sorbent (<0.5 €/cartridge) and its recyclability (up to 12 uses), among others good features.

Melamine sponge functionalized with carbon nanodots for the extraction of polyaromatic hydrocarbons and musks from environmental samples prior to their determination by gas chromatography-mass spectrometry

In this study, the functionalization of melamine sponge (MeS) with graphene quantum dots (GQDs) and its use as a sorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) and musks from environmental samples are presented. The MeS@GQDs is prepared by modification of the MeS with GQDs in a one-pot, single-step, in situ synthesis, using citric acid as carbon source. The produced MeS@GQDs was used to develop and optimize an analytical method based on solid-phase extraction mode, for the subsequent analysis of soil samples and treated effluents exploiting the extraction properties of the synthesized MeS@GQDs. The developed method not only presented satisfactory repeatability (RSD<8.7%) and inter-day repeatability (RSD<9.6%), but also its limits of quantification were found to be low (15-80 ng L−1). Moreover, the proposed method was linear in a wide range of concentrations (0.015-11.8 µg L−1) and the recoveries from difficult matrixes, such as treated effluents and soil, were satisfactory. Overall, the use of the sorbent for the development of a new analytical method was found to be advantageous as compared with other reported methods.

The use of H-form clinoptilolite to preconcentrate trace amounts of Nd(III) from aqueous solution under dynamic conditions

Rare earth elements (REE) are vital in the industry, particularly in the manufacturing of high-tech products. REE are emitted in enormous amounts into the environment as a result of their increased use in industry. The sorption technique is one of the most efficient ways to extract rare earth elements in low quantities. The results of a dynamic study of the sorption capabilities of the H-form of Transcarpathian clinoptilolite towards Nd(III) are presented in this work. X-ray diffraction, FT-IR, zeta potential analysis, and potentiometric titration were used to analyze the sorbent. The breakthrough capacity of H-clinoptilolite toward Nd(III) was 3.1 mg g−1 under ideal conditions (pH = 7.5, sorbent thermal treatment temperature: t = 150 °C). The desorption efficiency of Nd(III) has been investigated using acids and different mineral salt solutions. The optimum desorbing agent appeared to be acidified (pH 4) 1 M KNO3 solutions. A method for preconcentrating trace amounts of Nd(III) using acid-modified Transcarpathian clinoptilolite in a solid-phase extraction mode is proposed, followed by spectrophotometric measurement of this rare earth element.

Sorption of Yb(III) from aqueous solution on Na-clinoptilolite

The sorptive properties of the Na-modified Transcarpathian clinoptilolite towards Yb(III) under dynamic conditions were investigated. The sorption capacity of the Na-form of Transcarpathian clinoptilolite towards Yb(III) significantly depends on the concentration of ytterbium salt, the pH of solution and the temperature of the preliminary calcination of the sorbent. The buffer solution has been used to maintain the constant value of pH, ioniс strength of the solutions and to improve the metrological characteristics of preconcentration methods of Yb. The trace amounts of Yb(III) most effectively are sorbed with borate buffer solution. The final concentration of the borate buffer in the sample solution is 4·10 - 4 М. The sorption capacity of Na-clinoptilolite under optimal conditions (diameter of zeolite grains was 0.20–0.31 mm; flow rate of ytterbium(III) solution with concentration 1.0 µg/mL through sorbent was 5 mL/min; temperature of preliminary thermal treatment ~ 50 ºC and pH 9.5) was 8.1 mg ytterbium per 1 g of Na-modified clinoptilolite. The sorption of Yb(III) is carried out mainly by means of the adsorption of soluble hydrolyzed forms of Yb(III) on the zeolite surface. The influence of the most common water ions on the preconcentration of Yb(III) on the Na-form of Transcarpathian clinoptilolite has been established. The solutions of 1 M KCl acidified by a hydrochloric acid to pH 4.0 are the most effective desorbents of ytterbium(III) ions from Na-clinoptilolite. It provides a 99 % withdrawal of Yb from the zeolite matrix. The method for ytterbium trace amounts preconcentration from aqueous solutions in a solid phase extraction mode with a further determination of this rare earth element by a spectrophotometric method was developed. Keywords: sorption, solid phase extraction, ytterbium, Na-clinoptilolite.

Advances in solid-phase extraction for bisphenols in environmental samples

双酚类化合物作为一类内分泌干扰物广泛存在于环境介质中,经过多种途径迁移至人体后,可对人体产生内分泌毒性、细胞毒性、基因毒性、生殖毒性、二噁英毒性和神经毒性,已被加拿大政府风险评估识别为进一步优先控制名录。随着环境领域对双酚类化合物的广泛关注,相关研究工作逐渐向水、沉积物、灰尘和生物样品等多介质开拓。但是,由于不同环境样品在基质复杂性和污染物浓度水平等方面存在显著差异,开发提取效率高、净化选择性好、普适性强、操作简单、高通量的提取和净化方法,有助于实现环境介质中双酚类化合物的高灵敏、批量检测。近年来,新型前处理技术发展迅速,尤其是固相萃取技术,在双酚类化合物提取与净化方面取得了长足的发展,不仅在一定程度上克服了传统提取净化方法存在的耗时、耗力和耗溶剂等不足,而且为新型污染物分析提供了更多的技术支持。该文简述了典型双酚类化合物的理化性质、用途用量和环境危害,重点围绕新型固相萃取吸附剂开发和固相萃取模式转变两个方面,总结了固相萃取在双酚类化合物提取净化方法方面取得的进展。商品化固相萃取产品普适性强,在环境监测领域应用范围较广,适用于双酚类化合物的产品种类有限;新型吸附剂研发聚焦吸附容量(如介孔硅材料、碳纳米材料、金属-有机框架材料、环糊精)和选择性(如分子印迹聚合物和混合模式离子交换聚合物)两个方面,种类多样化可满足不同检测需求;越来越多的高灵敏分析仪器不断推向市场,为适应新的发展形势,固相萃取模式正逐渐向微型化、自动化、简易化等方向发展,如QuEChERS、固相微萃取、磁固相萃取等。

Preconcentration of Lutetium from Aqueous Solution by Transcarpathian Clinoptilolite

Sorptive properties of Transcarpathian clinoptilolite towards trace amounts of Lu(III) were studied under dynamic conditions. It is shown that this lanthanide is sorbed from the weakly alkaline solution (?? 10) most efficiently. The sorption capacity of clinoptilolite under the optimal conditions is equal to 9.37 mg g-1. The distribution of various species of Lu(III) in aqueous solutions at various total concentration of the lanthanide in the pH range from 4 to 13 was calculated. The best desorbent of Lu(III) is the 1 mol L-1 solution of NaCl, preacidified with the solution of HCl to a value of ?? 4.0. This desorbent enables 95-100 % of Lu(III) removal. The method of Lu(III) trace amounts preconcentration from aqueous samples in a solid phase extraction mode with the further determination of this rare earth element via the spectrophotometric method using arsenazo III was developed. The linearity of the proposed method was observed in the range of 1-12 ng mL-1 with the detection limit of 0.4 ng mL-1.

Solid Phase Extraction of Trace Amounts of Praseodymium Using Transcarpathian Clinoptilolite

Sorptive properties of the Transcarpathian clinoptilolite towards Pr(III) were studied under dynamic conditions. The sorption capacity of clinoptilolite under optimal conditions (sorbent grain diameter of 0.20–0.31 mm; pH 9.0, temperature of preliminary precalcination of 350 °C, and flow rate of the Pr(III) salt solution with the concentration of 1.0 μg·mL−1 through the sorbent of 5 mL·min−1) was equal to 47.5 mg·g−1. The best desorbent of Pr from the clinoptilolite was the 1 M solution of KCl acidified with HCl to a pH value of 3.0. The method of Pr(III) trace amounts preconcentration in a solid phase extraction mode with further determination of this REE via spectrophotometric technique was developed. The linearity of the proposed method was evaluated in the range of 2–100 ng·mL−1 with detection limit of 0.7 ng·mL−1.

A solid-phase extraction method using acid-modified Transcarpathian clinoptilolite for preconcentration of trace amounts of lead in water samples

The sorption properties of acid-modified Ukrainian Transcarpathian clinoptilolite towards lead aqueous solutions under dynamic conditions have been investigated. The obtained results show that this nanomaterial most effectively sorbs cationic aqua hydroxo complexes of Pb(II) ions. The optimal conditions for the sorption of Pb(II) on the acid-modified Transcarpathian clinoptilolite are as follows: temperature of H-clinoptilolite thermal pre-treatment—600 °C; sorbent grains diameter—0.20–0.31 mm; pH—8.5; flow rate of Pb(II) solution with the concentration of 0.5 µg mL−1 through the sorbent—5 mL min−1. The maximal sorption capacity value of the acid-modified Transcarpathian clinoptilolite towards Pb(II) is equal to 48.79 mg g−1, that is 4.5 times higher than the respective sorption capacity value of the natural form of this zeolite. The best desorbent of Pb(II) from acid-modified clinoptilolite is 1 M KCl (acidified with hydrochloric acid to pH 4.0). This desorbent removes 97% of sorbed Pb(II). The preconcentration method of Pb(II) nanogram amounts in the solid-phase extraction mode during the atomic absorption analysis of natural waters has been proposed. The linearity of the proposed method was evaluated in the range of 0.08–16 ng mL−1 with the detection limit of 0.025 ng mL−1. Due to acceptable recoveries (≥ 96%) and relative standard deviation (RSD) values (1.6–6.6%) from a spiked tap water.

C18-COOH Silica: Preparation, Characterisation and Its Application in Purification of Quaternary Ammonium Alkaloids from Coptis chinensis.

Traditional methods for isolating and purifying quaternary ammonium alkaloids from Coptis chinensis do not discriminate the target alkaloids from co-extractives. Mixed-mode analytical chromatography has the potential to improve the separation of analytes in more complex extracts and, when used in a solid-phase extraction mode, improve the purity of isolated compounds. To examine the high-performance liquid chromatographic separation capabilities of a mixed-mode, silica-based adsorbent and its application to the purification of quaternary ammonium alkaloids from Coptis chinensis based on solid-phase extraction. The C18-COOH silica was prepared via "thiol-ene" click chemistry. Its chromatographic performance was firstly investigated. It was employed as the solid-phase extraction sorbent to purify quaternary ammonium alkaloids. Hydrophobic, attractive/repulsive electrostatic and ion-exchange interactions were demonstrated to be the possible retention mechanisms of a C18-COOH silica stationary phase, which could separate analytes of various properties. In addition, to purify quaternary ammonium alkaloids from Coptis chinensis, the solid-phase extraction approach based on the C18-COOH silica provided a slightly higher purification efficiency (6.7%) than an alkaloid-salt precipitation protocol (5.3%). The method had satisfactory reproducibility, re-using the same solid-phase extraction column three times, with relative standard deviations ranging from 1.99% to 8.02% for the six target alkaloids. A multi-functionalised silica was synthesised via "click chemistry". As the high-performance liquid chromatographic stationary phase, the C18-COOH silica could be operated in trimodal reversed-phase/weak cation exchange/hydrophilic interaction mode. The C18-COOH silica also exhibited potential as solid-phase extraction sorbent in the purification of quaternary ammonium alkaloids from complex matrices. Copyright © 2017 John Wiley & Sons, Ltd.

Rhein functionalized magnetic chitosan as a selective solid phase extraction for determination isoflavones in soymilk

A new solid-phase extraction mode was developed for separation some flavones from the complex interference system. In the experiment, rhein anchored on magnetic chitosan microparticles, prepared facilely without removal of the template molecule, was used as sorbents for the extraction of target analytes; after completion of the extraction process, Fe3O4 particles acted as carrier to retrieve rhein functionalized magnetic chitosan microparticles (RMCMPs) from the sample solution. RMCMPs showed excellent selective adsorption capacity of isoflavones. The result suggested that the method was useful for fast determination and quantification of isoflavones in soymilk. The RMCMPs were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier transforms infrared spectrometer (FTIR).

Combined dispersive solid-phase extraction-dispersive liquid–liquid microextraction-derivatization for gas chromatography–mass spectrometric determination of aliphatic amines on atmospheric fine particles

Short-chain aliphatic amines are ubiquitous in the atmospheric environment. They play an important role in the formation and growth of atmospheric particles. As such, there is a pressing need to monitor these particle-bound compounds present at trace quantities. The present work describes an efficient, one-step microextraction technique for the preconcentration and detection of trace levels of 10 aliphatic amines on fine particles (particulate matter of 2.5μm or less (PM2.5)) in the atmosphere. After extraction of amines from particles in acidified water samples, carbon-based sorbents (in dispersive solid-phase extraction mode), and vortex agitation were utilized for simultaneous derivatization-extraction and dispersive liquid–liquid microextraction. The approach significantly increased the recoveries and enrichment of the amine derivatives. This one-step, combined technique is proposed for the first time. Several influential factors including type and concentration of derivatization reagent (for gas chromatographic separation), type of buffer, sample pH, types and volumes of extraction and disperser solvents, type and amount of sorbent, vortex time and temperature, desorption solvent type and volume, and salt content were investigated and optimized. Under the optimum conditions, high enrichment factors (in the range of between 307 and 382) and good reproducibility (relative standard deviations, below 7.0%, n=5) were achieved. The linearity ranged from 0.1μg/L–100μg/L, and from 0.5μg/L–100μg/L, depending on the analytes. The limits of detection were between 0.02μg/L (corresponding to ∼0.01ng/m3 in air) and 0.09μg/L (corresponding to ∼0.04ng/m3 in air). The developed method was successfully applied to the analysis of PM2.5 samples collected by air sampling through polytetrafluoroethylene filters. The concentration levels of amines ranged from 1.04 to 4.16ng/m3 in the air sampled.

Determination of tricyclic antidepressants in biota tissue and environmental waters by liquid chromatography-tandem mass spectrometry.

This work describes the optimization, validation, and application in real samples of accurate and precise analytical methods to determine tricyclic antidepressants (TCAs), including amitriptyline, nortriptyline, imipramine, and clomipramine in different environmental matrices, such as water (estuary, seawater, and wastewater treatment plant effluent) and biota (fish muscle, fish liver, and mussels), which would lead to supplement the scarce information on the presence of TCAs in aquatic organisms. The analysis step performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was fully optimized to improve the sensitivity of the separation and detection steps. The extraction of solid samples was accomplished using focused ultrasonic solid-liquid extraction (FUSLE), which required a low amount of sample (0.5 g), solvent (7 mL acetonitrile/H2O, 95:5 v/v) and short extraction time (30 s). In the optimisation of the clean-up step, mixed mode solid-phase extraction (SPE) using a strong cation exchanger rendered clean extracts and the best results in terms of extraction efficiency and matrix effect. The same SPE mode was also used for the extraction and pre-concentration of TCAs from environmental water matrices. The methods afforded satisfactory apparent recovery values (86-122%) and repeatability (RSD < 5%), regardless of the matrix. Finally, the developed methods were applied to the analysis of real samples from the Biscay Coast, where TCAs were detected in both water and biota samples up to 25.9 ng/L and 1.8 ng/g, respectively. Up to our knowledge, this is the first work using FUSLE for the determination of TCAs and one of the few analyzing TCAs in biota samples.

A solid-phase extraction approach for the identification of pharmaceutical–sludge adsorption mechanisms

It is important to understand the adsorption mechanism of chemicals and active pharmaceutical ingredients (API) on sewage sludge since wastewater treatment plants are the last barrier before the release of these compounds to the environment. Adsorption models were developed considering mostly hydrophobic API–sludge interaction. They have poor predictive ability, especially with ionisable compounds. This work proposes a solid-phase extraction (SPE) approach to estimate rapidly the API–sludge interaction. Sludge-filled SPE cartridges could not be percolated with API spiked mobile phases so different powders were tested as SPE sludge supports. Polytetrafluoroethylene (PTFE) was selected and tested at different PTFE/sludge ratios under eight different adsorption conditions with three API ionisable compounds. The PTFE/sludge mixtures with 50% or less sludge could be used in SPE mode for API sorption studies with methanol/water liquid phases. The results gave insights into API–sludge interactions. It was found that π–π, hydrogen-bonding and charge–charge interactions were as important as hydrophobicity in the adsorption mechanism of charged APIs on sludge.

Magnetic retrieval of chitosan: Extraction of bioactive constituents from green tea beverage samples

A new solid-phase extraction mode for magnetic retrieval of chitosan combined with high-performance liquid chromatography-diode array detection was proposed for the pre-concentration and determination of flavonoids in green tea beverage samples. In the experiment, chitosan was used as sorbents for the extraction of target analytes; after completion of the extraction process, Fe(3)O(4) nanoparticles acted as carrier to retrieve chitosan from the sample solution. Some important parameters influenced extraction efficiency of flavonoids, including the extraction mode, amounts of chitosan, pH of sample solution, extraction time, salt addition, amounts of Fe(3)O(4) nanoparticles, desorption solvent and desroption time, were optimized. Under the optimum conditions, the recoveries of analytes done on samples spiked with the target analytes were between 96.4% and 108.6%; relative standard deviations ranged from 0.6% to 8.7%. The correlation coefficients varied from 0.9917 to 0.9988. The limits of detection ranged from 5.4 to 16.8 ng mL(-1) at a signal-to-noise ratio of 3. All four different brands of green tea beverage samples were successfully analyzed by the proposed method.

Supported hydrophobic ionic liquid on nano-silica for adsorption of lead

The hydrophobic character incorporated into 1-methyl-3-octylimidazolium bis(trifluoromethyl-sulfonyl)imide [OMIM +Tf 2N −] based on both the anion and cation natures was employed to develop a novel solid phase extraction medium based on physical adsorption approach. Two modified nano-silica sorbents were synthesized via direct immobilization of [OMIM +Tf 2N −] on the surface of active nano-silica [NSi-OH] and amino nano-silica [NSi-NH 2] for the formation of [NSi-OH-OMIM +Tf 2N −] and [NSi-NH 2-OMIM +Tf 2N −], respectively. Surface characterization was confirmed by TGA, FT-IR and SEM. The surface coverage values were identified in the range of 1.223–1.272 mmol g −1. Modified sorbents were extensively studied and characterized by their high similarity and affinity for lead extraction without the need for chelating intermediate. Excellent sorption capacity values (0.5–0.9 and 0.8–1.3 mmol g −1) of lead were determined in pH 1–7. Other factors such as reaction contact time, sorbent dose, initial metal ion concentration and interfering ions were studied to spot more light on the sorption capability of loaded hydrophobic ionic liquid for application in the solid phase extraction mode. These sorbents were successfully implemented for removal and preconcentration of lead from various water samples via application of a multi-stage micro-column giving rise to percentage recovery values of lead in the range of 98.0–100.0 ± 3.0–4%.

Comparison of off- and in-line solid-phase extraction for enhancing sensitivity in capillary electrophoresis using ochratoxin as a model compound

This paper proposes and compares two approaches based on off- and in-line solid-phase extraction (SPE), intended to enhance sensitivity in capillary electrophoresis with ultraviolet detection (CE-UV) using as a model the determination of ochratoxin A (OA) in river water samples. In the off-line SPE mode, the reversed-phase sorbent (octadecilsylane, C(18)) selectively retains the target analyte (OA) and allows large volumes of the sample (70 mL) to be introduced and subsequently eluted in a small volume (0.1 mL) of an appropriate solution. In the in-line SPE mode, a custom-made microcartridge is inserted near the inlet of the capillary, which is filled with the same C(18) sorbent. This solid phase selectively retains OA present in a sample volume as low as approximately 640 microL for subsequent elution with ca. 135 nL of an appropriate eluent. The limit of detection (LOD) obtained with the in-line SPE method was 1 ng L(-1), which is 3 orders of magnitude lower than that obtained with CE-UV and roughly 1 order lower than that provided by the off-line SPE-CE-UV method.