Magnetic dual task-specific polymeric ionic liquid nanoparticles for preconcentration and determination of gold, palladium and platinum prior to their quantitation by graphite furnace AAS

Liquid- and Solid-based Separations Employing Ionic Liquids for the Recovery of Platinum Group Metals Typically Encountered in Catalytic Converters: A Review

The wide application range and ascending demand for platinum group metals combined with the progressive depletion of their natural resources renders their efficient recycling a very important and pressing matter. Primarily environmental considerations associated with state-of-the-art recovery processes have shifted the focus of the scientific community toward the investigation of alternative recycling approaches. Within this context, ionic liquids have gained considerable attention in the last two decades chiefly sparked by properties such as tunabilty, low-volatility, and relatively easy recyclability. In this review an understanding of the state-of-the-art processes, including their drawbacks and limitations, is provided. The core of the discussion is focused on platinum group metal recovery with ionic liquid-based systems. A brief insight in some environmental considerations related to ionic liquids is also provided while some discussion on research gaps, common misconceptions related to ionic liquids and outlook on unresolved issues could not be absent from this review.

Gold determination in soil by ICP-MS: comparison of sample pretreatment methods

At present, the direct gold determination in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) is still an arduous challenge due to both spectral and background interferences. It is very important and necessary to study the pretreatment processes; therefore, the polyurethane foam treatment and sample digestion methods are explored and compared here. The experimental results showed that the gold adsorption rate of treated foam was significantly improved as the impurities in the foam were cleaned up, and the potential difference of the liquid membrane was increased. Meanwhile, the combination of the foam enrichment and thiourea desorption achieved the selective adsorption and desorption of gold ions, eliminated the interference of coexisting ions, and perfected the detection limits. Compared with the traditional electric heating plate digestion method, microwave digestion, a closed digestion method, had the advantages of less sample and reagent dosage, short time consumption, high degree of automation, thorough digestion, good security, and environmental friendliness and met the requirements of green chemistry development. The proposed microwave digestion-foam enrichment-thiourea desorption-ICP-MS determination method was applied to the gold test in soil samples of the actual gold mining area. It has the great potential as a routine laboratory procedure.

Adjusting the chromatographic properties of poly(ionic liquid)-modified stationary phases by substitution on the imidazolium cation

Poly(ionic liquid)-modified stationary phases can have multiple interactions with solutes. However, in most stationary phases, separation selectivity is adjusted by changing the poly(ionic liquid) anions. In this work, two poly(ionic liquid)-modified silica stationary phases were prepared by introducing the cyano or tetrazolyl group on the pendant imidazolium cation on the polymer chains. Various analytes were selected to investigate their mechanism of retention in the stationary phases using different mobile phases. Two poly(ionic liquid)-modified stationary phases can provide various interactions toward solutes. Compared to the cyano-functionalized poly(ionic liquid) stationary phase, the tetrazolyl-functionalized poly(ionic liquid) stationary phase provides additional cation-exchange and π-π interactions, resulting in different separation selectivity toward analytes. Finally, applicability of the developed stationary phases was demonstrated by the efficient separation of nonsteroidal anti-inflammatory drugs.

Evolution of Environmentally Friendly Strategies for Metal Extraction

The demand for the recovery of valuable metals and the need to understand the impact of heavy metals in the environment on human and aquatic life has led to the development of new methods for the extraction, recovery, and analysis of metal ions. With special emphasis on environmentally friendly approaches, efforts have been made to consider strategies that minimize the use of organic solvents, apply micromethodology, limit waste, reduce costs, are safe, and utilize benign or reusable materials. This review discusses recent developments in liquid- and solid-phase extraction techniques. Liquid-based methods include advances in the application of aqueous two- and three-phase systems, liquid membranes, and cloud point extraction. Recent progress in exploiting new sorbent materials for solid-phase extraction (SPE), solid-phase microextraction (SPME), and bulk extractions will also be discussed.

Magnetic mesoporous nanoparticles modified with poly(ionic liquids) with multi-functional groups for enrichment and determination of pyrethroid residues in apples

Considering that the determination of pyrethroid residues is of value for the safety of food, a new poly(ionic liquid)-functionalized magnetic mesoporous nanoparticle was designed and used as an adsorbent in magnetic solid-phase extraction for the enrichment of eight pyrethroids. The porous structure and large surface area of the mesoporous silica shell endow the adsorbent with abundant binding sites. In contrast to the reported poly(ionic liquids) with only one kind of functional group in the cationic part, the new poly(ionic liquids) with mixed cyano and phenyl groups in cationic part matched the chemical structure of the analytes to improve extraction efficiency. Under the optimum conditions, an effective method was established for the determination of eight pyrethroids in apples. Adsorption equilibrium can be quickly reached in 1 min, greatly decreasing the extraction time. The linearity range was found to be 10-200 ng/g, and the detection limits ranged from 0.24 to 1.99 ng/g. Recoveries of analytes in apple samples ranged from 87.3 to 119.0%, with relative standard deviations varying in the range of 3-21.2% (intraday) and 0.3-15.2% (interday). The results indicate that the proposed method is a good candidate for pyrethroid residues in apple samples.

A porous organic polymer with magnetic nanoparticles on a chip array for preconcentration of platinum(IV), gold(III) and bismuth(III) prior to their on-line quantitation by ICP-MS

A chip-based array is described for magnetic solid-phase microextraction (MSPME) of the ions of Pt, Au and Bi. Magnetic porous organic polymers (MOPs) prepared from magnetite nanoparticles and 1,3,5-tris(4-aminophenyl)benzene are introduced as a novel adsorbent. Eight solid phase extraction columns packed with MOPs were integrated in parallel on a microfluidic chip for array microextraction. After elution with a 12% (m/v) solution of cysteamine hydrochloride (pH 8.0), the eluent is introduced into an ICP-MS instrument for quantification. Under the optimized conditions, the limits of detection for Pt, Au and Bi are 8.6, 4.4 and 3.4 ng L^-1, respectively. The sample throughput is 7 h^-1, and the adsorption capacities are 32, 24 and 24 μg mg^-1 for Pt, Au and Bi, respectively. The method was validated by the determination of Bi in a certified reference material (GSH-1A; human hair), and the values obtained coincided with the certified value. This method was also applied to the determination of Pt, Au and Bi in (spiked) urine and cell samples, and good recoveries (85.8-113%) were achieved. The method is highly sensitive and has a high throughput and a low sample/reagent consumption (with 500 HeLa cells consumed). Graphical abstract Schematic presentation of the magnetic packed column, microfluidic chip, and online chip-based MSPME-ICPMS system. Design sketch of the online system: microextraction unit (blue lines), microvalves (black lines), outlet channels (yellow lines), permanent magnets (red), urine and cell samples.

Comparative Study on Two Pretreatment Processes for Chemical Phase Analysis of Gold in Geological Samples by Atomic Absorption Spectrometry

Sample pretreatment is important for chemical phase analysis of elements. In this study, the geological samples of the Laozuoshan gold mine are chosen to pretreat by ultrasonic centrifugation and cyclotron oscillation, and the content of gold in eight chemical phases (water-soluble, ion exchange and clay adsorption, organic matter bound, iron-manganese oxide bound, naked or seminaked, carbonate bound, sulfide bound, and insoluble silicate states) is determined by atomic absorption spectrometry. The results show that the gold content of water-soluble, ion exchange and clay adsorption, iron-manganese oxide, and naked or seminaked states in the rock and ore samples is low, and some samples have high gold content of insoluble silicate states in the two methods. However, the gold content of organic matter bound, carbonate bound, and sulfide bound states obtained by ultrasonic centrifugation and cyclotron oscillation methods is significantly different. According to the X-ray fluorescence spectrometry data and the actual geological condition, the result given by the cyclotron oscillation method is more reasonable. The gold content of sulfide bound state in sediment samples is the highest and consistent with the mineral information, which could be applied to preliminarily predict the rock and ore conditions in the corresponding mining areas. In contrast with ultrasonic centrifugation, the cyclotron oscillation method has the advantages of simplicity, high efficiency, practicality, and environmental protection, and it can be better used for the determination of gold chemical phase state in geological samples by atomic absorption spectrometry.

Silica-coated magnetic iron oxide functionalized with hydrophobic polymeric ionic liquid: a promising nanoscale sorbent for simultaneous extraction of antidiabetic drugs from human plasma prior to their quantitation by HPLC

Herein, silica-coated iron oxide nanoparticles modified with imidazolium-based polymeric ionic liquid (Fe₃O₄@SiO₂@PIL) were fabricated as a sustainable sorbent for magnetic solid-phase extraction (MSPE) and simultaneous determination of trace antidiabetic drugs in human plasma by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The Fe₃O₄ core was functionalized by silica (SiO₂) and vinyl layers where the ionic liquid 1-vinyl-3-octylimidazolium bromide (VOIM-Br) was attached through a free radical copolymerization process. In order to achieve hydrophobic magnetic nanoparticles and increase the merits of the sorbent, Br⁻ anions were synthetically replaced with PF₆⁻. The properties and morphology of the sorbent were characterized by various techniques and all the results illustrated the prosperous synthesis of Fe₃O₄@SiO₂@PIL. A comprehensive study was carried out to investigate and optimize various parameters affecting the extraction efficiency. The limit of detection (LOD, S/N = 3) for empagliflozin, metformin and canagliflozin was 1.3, 6.0 and 0.8 ng mL⁻¹, respectively. Linearity (0.997 ≥ r² ≥ 0.993) and linear concentration ranges of 5.0–1200.0, 20.0–1800.0 and 5.0–1000.0 ng mL⁻¹ were obtained for empagliflozin, metformin and canagliflozin, respectively. Intra-assay (3.8–7.5%, n = 9) and inter-assay (3.2–8.5%, n = 12) precisions as well as accuracies (≤9.1%) displayed good efficiency of the method. Finally, the method was applied for the quantitation of antidiabetic drugs in human plasma after oral administration and main pharmacokinetic data including T_max (h), C_max (ng mL⁻¹), AUC_0–24 (ng h mL⁻¹), AUC_0–∞ (ng h mL⁻¹), and T_1/2 (h) were evaluated.

A sustainable nanoscale core–shell modified with hydrophobic polymeric ionic liquid was fabricated for simultaneous extraction and determination of antidiabetic drugs.