Optimization of supramolecular solvent microextraction prior to graphite furnace atomic absorption spectrometry for total selenium determination in food and environmental samples

Poly-(ionic liquid) coated with magnetic nanoparticles for micro solid phase extraction of polycyclic aromatic hydrocarbons in food samples

Poly(methyl methacrylate-vinyl imidazole bromide) (poly-MMA-IL)-grafted magnetic nanoparticles were successfully developed and applied in the micro-magnetic solid phase extraction (μ-MSPE) for 16 types of polycyclic aromatic hydrocarbons (PAHs) from tea, fried food, and grilled food samples via gas chromatography flame ionization detector (GC-FID). One variable at a time (OVAT) and response surface methodology (RSM) were used for efficient optimization. The validation method showed a good coefficient of determination (R2) ranging from 0.9901 to 0.9982 (n = 3) with linearity of 0.2 μg L-1-500 μg L-1. Detection and quantification limits were 0.06 µg L-1-0.32 µg L-1 and 0.18 µg L-1-0.97 µg L-1. Additionally, satisfactory reproducibility was attained with intra-day and inter-day precisions having RSD ranges of 3.6%-11.1%. The spiked recovery value of 16 PAHs in fried food, grilled food and tea samples obtained from the night market in Malaysia ranged from 80%-12%, respectively.

Determination of Selenium in Selenium-Enriched Products by Specific Ratiometric Fluorescence

Selenium (Se), as one of the essential and nutrient components of living organisms and plants, plays an important role in life activities, while excessive selenium is hazardous to human health. So, the establishment of an effective method for simple, rapid, and highly sensitive determination of selenium content is crucial in the field of food composition analysis and other areas. In this paper, a novel and simple ratiometric fluorescence method for the determination of Se has been developed using 9-anthracenemethanol (AM) as the ratiometric fluorescence reagent on the basis of the conventional fluorometric assay which utilized 2,3-diaminonapthalene (DAN) as fluorescent ligand. The ratiometric method was compared with the conventional method with respect to precision and accuracy. The inter-day and intra-day precisions (RSDs) of the ratiometric fluorescence method ranged from 2.08 to 2.78% and 1.28 to 1.84%, with mean recoveries of 93.2~98.0% and limit of detection (LOD) and limit of quantification (LOQ) of 0.0016 and 0.0049 μg/mL, respectively. This method was successfully applied to the determination of total selenium in selenium-enriched milk and selenium-supplemented shampoo, with the results in agreement with those obtained by inductively coupled plasma mass spectrometer (ICP-MS). The results demonstrated that the precision and accuracy of the ratiometric fluorescence method were superior to those of the conventional fluorescence method, and the interferences of various environmental factors were effectively eliminated. The precision and accuracy of the conventional method can be significantly improved by simply adding an elaborately selected ratiometric fluorescence reagent, and the new method will have broader practical applications.

Poly-(MMA-IL) filter paper: A new class of paper-based analytical device for thin-film microextraction of multi-class antibiotics in environmental water samples using LC-MS/MS analysis

A paper-based polymeric ionic liquid (p-Poly-(MMA-IL)) was successfully developed by grafting the polymeric ionic liquid on the surface of commercial filter paper (FP) by using the dipping method, presenting a new cost-effective film. The newly developed p-Poly-(MMA-IL) FP was then applied as a paper-based thin-film microextraction (p-TFME) analytical device to extract 14 compounds as representative of five groups of antibiotic drugs, which were sulfonamides, tetracyclines, fluoroquinolones, penicillin and macrolides in environmental water samples. Besides, p-Poly-(MMA-IL) FP, p-Poly-(MMA) FP, and unmodified filter paper were successfully characterised by FTIR, NMR, FESEM, TGA, and XRD techniques. They underwent significant parameters optimisation, which affected the extraction efficiency. Under optimal conditions, the proposed (p-Poly-(MMA-IL) FP-TFME) device method was evaluated and applied to analyse multi-class antibiotic drugs in environmental water samples by using a liquid chromatography-mass spectrometry (LC-MS). The validation method showed that a good linearity (0.1 μg L^-1 - 500 μg L^-1) was noted (R² > 0.993, n = 3). Detection and quantification limits were within 0.05 μg L^-1 - 4.52 μg L^-1 and 0.15 μg L^-1 - 13.6 μg L^-1, respectively. The relative standard deviation (RSD) values ranged at 1.4%-12.2% (intra-day, n = 15) and 4.4%-11.0% (inter-day, n = 10). The extraction recoveries of environmental water samples ranged from 79.1% to 126.8%, with an RSD of less than 15.4% (n = 3). The newly developed paper-based polymeric ionic liquid (p-Poly-(MMA-IL) FP) for analysis of multi-class antibiotic drugs under the p-TFME analytical device procedure was successfully achieved with limited sample volume and organic solvent, fast extraction, and feasible in daily analysis. The detection concentration and relative RSD of multi-class antibiotics determined in various environmental water samples by the proposed method (n = 5) were within 0.44 μg L^-1 - 54.41 μg L^-1 and 0.69%-15.56%, respectively. These results signified the potential of the p-Poly-(MMA-IL) FP-TFME device as an efficient, sensitive and environmentally friendly approach for analysing antibiotics.

A critical review of selected preconcentration techniques used for selenium determination in analytical samples

Selenium (Se) is considered to be an essential trace element needed for all living organisms. The importance, deficiency, and toxic effects of Se mainly depend on its quantity and chemical nature. It has been observed that the inorganic versions of Se are more hazardous than the organic versions. This review is mainly focused on the application of different extraction methods used for Se extraction and determination such as microextraction, solid-phase extraction (SPE), and their modified modes in the last 12 years. The use of different dispersive medium (magnetic field, ultrasonic radiation, and vortex agitator) to enhance Se separation is also part of this review. The usage of environmentally friendly solvents such as supramolecular solvents, hydrophobic deep eutectic solvents (DESs), and ionic liquids (ILs) are also the focus of attention in this review. This review is also emphasized the application of advanced microextraction methods, particularly liquid-phase microextraction (LPME). The most recent advances in LPME extraction techniques for Se in various environmental samples, as well as their prospects, are reviewed. Additionally, a summary of cheap, simple, and accurate techniques that have not yet been used to determine small amounts of Se has been provided.

Reliable Quantification of Ultratrace Selenium in Food, Beverages, and Water Samples by Cloud Point Extraction and Spectrometric Analysis

Selenium is a trace element essential for the proper functioning of human body. Since it can only be obtained through our diet, knowing its concentrations in different food products is of particular importance. The measurement of selenium content in complex food matrices has traditionally been a challenge due to the very low concentrations involved. Some of the difficulties may arise from the abundance of various compounds, which are additionally present in examined material at different concentration levels. The solution to this problem is the efficient separation/preconcentration of selenium from the analyzed matrix, followed by its reliable quantification. This review offers an insight into cloud point extraction, a separation technique that is often used in conjunction with spectrometric analysis. The method allows for collecting information on selenium levels in waters of different complexity (drinking water, river and lake waters), beverages (wine, juices), and a broad range of food (cereals, legumes, fresh fruits and vegetables, tea, mushrooms, nuts, etc.).

A simple and green ultrasound liquid-liquid microextraction method based on low viscous hydrophobic deep eutectic solvent for the preconcentration and separation of selenium in water and food samples prior to HG-AAS detection

A simple and green ultrasound liquid-liquid microextraction method based on low viscous hydrophobic deep eutectic solvent (ULLME-LV-HDES) was proposed for the preconcentration and separation of selenium prior to HG-AAS detection. Six different DESs were prepared for the extraction of selenium. Quercetin was used complexing agent for Se(IV) ions. Various analytical parameters such as pH, quercetin amount, DES type and its volume, sonication time, sample volume were optimized. Tolerance limits of anion, cation and transition metal ions were studied. Preconcentration and enhancement factor were found 62.5 and 121. Under the optimum conditions, limit of detection was found 0.25 ng L^-1 with calibration range of 0.8-120 ng L^-1. Relative standard deviation was found 3.2%. The accuracy of the method was confirmed with certified reference materials (NIST 1567a Wheat flour and NIST 1548a Typical diet). Finally, the developed method was successfully applied to food and water samples.

Alcohol-DES based vortex assisted homogenous liquid-liquid microextraction approach for the determination of total selenium in food samples by hydride generation AAS: Insights from theoretical and experimental studies

This research article proposes a simple, quick, green and cheap approach for the determination of total selenium in food samples using alcohol-DES based vortex-assisted homogenous liquid-liquid microextraction (alcohol-DES-VA-HLLME) combination with hydride generation atomic absorption spectrometry (HG AAS). Analyte, complexing agent and working pH were Se(IV), Sudan-II and pH 4.0, respectively. In order to analyze the nature of the chemical interaction between Se(IV) ion and Sudan-II ligand, experimental results were supported with computational chemistry tools calculating quantum chemical descriptors like frontier orbital energies, hardness, softness, electronegativity, electrophilicity, nucleophilicity, transferred electron from the ligand to ion, electron donating power, electron accepting power, complexation energy, molecule-ion interaction energy. In addition, the alcohol-DES-VA-HLLME method was earned a good detection limit of 3.5 ng L^-1 and a wide calibration curve in the concentration range of 12-300 ng L^-1 (r: 0.9981). The validity of the method was evaluated by analyzing the two standard reference material (SRMs). The recoveries and relative standard deviations for 25 and 100 ng L^-1 of Se(IV) (N:5) were in the range of 1.2-2.5% and 92.1-103.7% respectively, which proved acceptable. The analytical results showed that the proposed method had important features such as cheapness, green, quick extraction and reuse, which made it attractive for the determination and efficient extraction of total selenium in the food samples.

Determination of benzo(a)pyrene in fried and baked foods by HPLC combined with vesicular coacervative supramolecular solvent extraction

A simple, rapid and low-cost determination method of benzo(a)pyrene in fried and baked foods was proposed by high performance liquid chromatography combined with vesicular coacervative supramolecular solvent (SUPRAS) extraction. The vesicular coacervate was composed of 1-octanol and tetrabutylammonium bromide. 200 mg of dried samples with 600 μL SUPRAS could be mixed to extract benzo(a)pyrene. Neither evaporation nor further clean-up steps for the extracts were needed. The overall sample treatment took approximately 30 min, and several samples could be simultaneously treated using conventional lab equipment. Then, benzo(a)pyrene was analyzed via liquid chromatography-fluorescence detection. Parameters affecting the extraction efficiency were investigated and optimized. The results showed good linearity of benzo(a)pyrene with the coefficients of determination (R ²) of more than 0.9999 in the range of 0.1-50.0 µg/kg. The limit of detection of the method was 0.11 µg/kg. Recoveries for spiked samples in the range of 1-10 µg/kg were between 89.86 and 100.01%, with relative standard deviations from 1.20 to 3.20%. Benzo(a)pyrene was present in food samples (including instant noodles, biscuits, rice crust and fried bread stick) at concentrations in the range of 0.08-0.39 µg/kg according to the proposed method. The proposed pretreatment method significantly reduces the analysis time. Furthermore, the solventless approach is in accordance with the green chemistry development trend and has significant application prospects.

Metal–organic framework based micro solid phase extraction coupled with supramolecular solvent microextraction to determine copper in water and food samples

D-μ-SPE-SUPRAS-ME followed by GFAAS was successfully used for preconcentration and determination of copper in real samples.

Ultrasonic assisted dispersive liquid-liquid microextraction method based on deep eutectic solvent for speciation, preconcentration and determination of selenium species (IV) and (VI) in water and food samples

A novel ultrasound-assisted liquid phase microextraction (UALPME) based on environmental friendly extractants, deep eutectic solvent (DES) was first time presented for speciation of selenium. In present study, five DES solvents of different composition was prepared and used as efficient extractive medium for hydrophobic chelate of Se(IV) with 3,3'-Diaminobenzidine (DAB). The total inorganic Se species were determined after pre-reduction of Se(VI) to Se(IV), prior to applying developed method. The concentration of Se(VI) was calculated by the difference of Se(IV) values and total selenium contents. The concentration of Se in DES rich phase was measured with electrothermal atomic absorption spectrometer (ETAAS). The effects of different parameters on extraction efficiency of study analyte, including pH, ligand concentration, type and volume of DES, sonication time, volumes tetrahydrofuran and aqueous samples were examined. At the optimum conditions, limit of detection and quantification, preconcentration factor, and relative standard deviation (RSD %) were determined as 4.61ngL^-1, 15.4ngL^-1, 50% and 4.1%, respectively. The accuracy of the presented method was confirmed by analysis of certified reference material and standard addition method for different water and ice tea samples. The developed method was effectively applied to real water and food samples.