An efficient biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles for quantification of bisphenol A in water samples by gas chromatography‐mass spectrometry detection

In this work, a simple, fast, sensitive, and environmentally friendly method was developed for preconcentration and quantitative measurement of bisphenol A in water samples using gas chromatography with mass spectrometry. The preconcentration approach, namely biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles was performed based on the formation of microdroplet of rhamnolipid biosurfactant throughout the aqueous samples, which accelerates the mass transfer process between the extraction solvent and sample solution. The process is then followed by the application of magnetic nanoparticles for easy retrieval of the analyte‐containing extraction solvent. Several important variables were optimized comprehensively including type of disperser solvent and desorption solvent, rhamnolipid concentration, volume of disperser solvent, amount of magnetic nanoparticles, extraction time, desorption time, ionic strength, and sample pH. Under the optimized microextraction and gas chromatography with mass spectrometry conditions, the method demonstrated good linearity over the range of 0.5–500 µg/L with a coefficient of determination of R² = 0.9904, low limit of detection (0.15 µg/L) and limit of quantification (0.50 µg/L) of bisphenol A, good analyte recoveries (84–120%) and acceptable relative standard deviation (1.8–14.9%, n = 6). The proposed method was successfully applied to three environmental water samples, and bisphenol A was detected in all samples.     

Humic acid functionalized hyperbranched polytriazine based dispersive solid‐phase extraction for acaricides determination in tea matrix

Hyperbranched polytriazine functionalized with humic acid was prepared and developed as new sorbents for dispersive solid‐phase extraction of three acaricides (clofentezine, fenpyroximate, and pyridaben) in tea samples combined with high‐performance liquid chromatography detection. The sorbents were characterized by scanning electron microscopy, energy dispersive spectroscopy, Zeta‐potential, and Fourier transform infrared spectroscopy. The extraction parameters (extraction time, ionic strength, desorption conditions) were optimized. The adsorption mechanism was evaluated utilizing Fourier transform infrared spectra. Under optimum conditions, satisfactory analytical performances were achieved, which included high precision (1.33–9.62%), low limits of detection (0.19–3.54 µg/L), and wide linear range (2.5–500 µg/L) for the analysis of the acaricides. Moreover, the proposed method proved highly effective for the determination of acaricides in tea samples, with the relative recoveries in the range of 65.20–108.13% and relative standard deviations < 9.87%. The method has great application potential for the detection of acaricides in tea samples.     

Developing a novel packed in‐tube solid‐phase extraction method for determination ∆9‐tetrahydrocannabinol in biological samples and cannabis leaves

A novel plate‐like nano‐sorbent based on copper/cobalt/chromium layered double hydroxide was synthesized by a simple coprecipitation method. The synthesized nanoparticels were introduced into a stainless steel cartridge using a dry packing method. Then, the packed cartridge was introduced as a novel on‐line “packed in‐tube” configuration and followed by high performance liquid chromatography for the determination of trace amounts of ^?9‐tetrahydrocannabinol from biological samples and cannabis leaves. The as‐prepared sorbent exhibited long lifetime, good chemical stability, and high anion‐exchange capacity. Several important factors affecting the extraction efficiency, such as extraction and desorption times, pH of the sample solution and flow rates of the sample and eluent solutions, were investigated and optimized. Under optimized conditions, this method showed good linearity for ^?9‐tetrahydrocannabinol in the ranges of 0.09–500, 0.3–500, and 0.4–500 µg/L with coefficients of determination of 0.9999, 0.9991, and 0.9994 in water, serum and plasma samples, respectively. The inter‐ and intra‐assay precisions (n = 3) were respectively in the ranges of 1.8–4.6% and 1.9–4.0% at three concentration levels of 10, 50, and 100 µg/L. The limits of detection were also in the range of 0.02–0.1 µg/L.     

Evaluation of two membrane‐based microextraction techniques for the determination of endocrine disruptors in aqueous samples by HPLC with diode array detection

In this study, the viability of two membrane‐based microextraction techniques for the determination of endocrine disruptors by high‐performance liquid chromatography with diode array detection was evaluated: hollow fiber microporous membrane liquid–liquid extraction and hollow‐fiber‐supported dispersive liquid–liquid microextraction. The extraction efficiencies obtained for methylparaben, ethylparaben, bisphenol A, benzophenone, and 2‐ethylhexyl‐4‐methoxycinnamate from aqueous matrices obtained using both approaches were compared and showed that hollow fiber microporous membrane liquid–liquid extraction exhibited higher extraction efficiency for most of the compounds studied. Therefore, a detailed optimization of the extraction procedure was carried out with this technique. The optimization of the extraction conditions and liquid desorption were performed by univariate analysis. The optimal conditions for the method were supported liquid membrane with 1‐octanol for 10 s, sample pH 7, addition of 15% w/v of NaCl, extraction time of 30 min, and liquid desorption in 150 μL of acetonitrile/methanol (50:50 v/v) for 5 min. The linear correlation coefficients were higher than 0.9936. The limits of detection were 0.5–4.6 μg/L and the limits of quantification were 2–16 μg/L. The analyte relative recoveries were 67–116%, and the relative standard deviations were less than 15.5%.     

Trace analysis of rimantadine in human urine after dispersive liquid liquid microextraction followed by liquid chromatography–post column derivatization

The first dispersive liquid liquid microextraction scheme followed by liquid chromatography‐post column derivatization for the determination of the antiviral drug rimantadine in urine samples is demonstrated. The effect of the type and volume of organic extraction solvent, type and volume of disperser solvent, sample pH, ionic strength, extraction time, and centrifugation speed on the extraction efficiency were studied. Rimantadine and the internal standard (amantadine) were chromatographed using a reversed phase monolithic stationary phase with a mixture of equal volumes of methanol and phosphate buffer (pH = 3) as mobile phase. On‐line post‐column derivatization of the analyte was performed using a “two‐stream” manifold with o‐phthalaldehyde and N‐acetyl‐cysteine at alkaline medium. Under the optimized extraction conditions, the enrichment factor of rimantadine was 58. The linear range was 5–100 µg/L with correlation coefficient r of 0.9984 while the limit of detection achieved was 0.5 µg/L. The within‐day and between‐day precision for the tested concentration levels were less than 14.3% and the mean recoveries obtained from the spiked samples were ranged between 87.5 and 113.9%. The main advantages of the proposed method are the simplicity of operation, rapidity, low cost, and low limit of detection of the analyte.     

Extraction and determination of trace amounts of three anticancer pharmaceuticals in urine by three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents followed by high‐performance liquid chromatography

An automated three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents followed by high‐performance liquid chromatography with UV–Vis detection method was applied for the extraction and determination of exemestane, letrozole, and paclitaxel in water and urine samples. n‐Dodecane was selected as the supported liquid membrane and its polarity was justified by trioctylphosphine oxide. Acetonitrile was used as an organic acceptor phase with desirable immiscibility having n‐dodecane. All the effective parameters of the microextraction procedure such as type of the organic acceptor phase, the supported liquid membrane composition, extraction time, pH of the donor phase, hollow fiber length, stirring rate, and ionic strength were evaluated and optimized separately by a one variable at‐a‐time method. Under the optimal conditions, the linear dynamic ranges were 1.8–200 (R² = 0.9991), 0.9–200 (R² = 0.9987) and 1.2–200 μg/L (R² = 0.9983), and the limits of detection were 0.6, 0.3, and 0.4 μg/L for exemestane, letrozole, and paclitaxel, respectively. To evaluate the capability of the proposed method in the analysis of biological samples, three different urinary samples were analyzed under the optimal conditions. The relative recoveries of the three pharmaceuticals were in the range of 91–107.3% for these three analytes.     

In‐line coupling of supported liquid membrane extraction across nanofibrous membrane to capillary electrophoresis for analysis of basic drugs from undiluted body fluids

Planar polyamide 6 nanofibrous membrane was for the first time used in direct coupling of supported liquid membrane (SLM) extraction to CE analysis. Disposable microextraction device with the nanofibrous membrane was preassembled and stored for immediate use. The membrane in the device was impregnated with 1 µL of 1‐ethyl‐2‐nitrobenzene and the device was subsequently filled with 10 µL of acceptor solution (10 mM HCl) and 15 µL of donor solution (sample). The device was in‐line coupled to CE system for selective extraction and direct injection, separation and quantification of model basic drugs (nortriptyline, haloperidol, loperamide and papaverine) from standard saline solutions (150 mM NaCl) and from undiluted human body fluids (urine and blood plasma). Compared to standard polypropylene supporting material, the nanofibrous membrane demonstrated superior characteristics in terms of lower consumption of organic solvents, constant volumes of operational solutions, full transparency and possibility to preassemble the devices. Extraction parameters were better or comparable for the nanofibrous vs. the polypropylene membrane and the hyphenated SLM‐CE method with the nanofibrous membrane was characterized by good repeatability (RSD ≤ 11.3%), linearity (r² ≥ 0.9953; 0.5–20 mg/L), sensitivity (LOD ≤ 0.4 mg/L) and transfer (27–126%) of the basic drugs.     

Date pits waste as a solid phase extraction sorbent for the analysis of lead in wastewater and for use in manufacturing brick: An eco-friendly waste management approach

Lead (Pb(II)), an extremely hazardous heavy metal that has been shown to have detrimental effects on both the environment and humans, mostly gets into the ecosystem through industrial activities. In this work, a new solid-phase extraction (SPE) based on treated date pits bio-sorbent and iCAP Q inductively-coupled plasma mass spectrometry (iCAP Q ICP/MS) method has been optimized for the trace determination of Pb(II) in various industrial wastewater effluents. A cost-effective biomass material was prepared from date pits (DP), and chemically modified with H₂O₂ and successively used as SPE bio-sorbent for Pb(II) extraction. Extracting solutions for instance H₂SO₄, HNO₃ and HCl at various concentrations (1–5 mM) were optimized, and best extraction of Pb(II) was obtained by HCl (1 mM). The optimized SPE and iCAP Q ICP/MS method has offered excellent validation conditions in terms of coefficient of determination (CoD, R² > 0.999), detection limit (DL, 0.011 µg/L), quantification limit (QL, 0.034 µg/L), and run-to-run and day-to-day precision (RSD < 6 %). The optimized procedure was practically applied in the determination of Pb(II) in industrial wastewater comprising iron and steel, textile, printing and battery industries. Among the analyzed samples, the battery industry produced higher amounts of Pb(II) (18.55 µg/L) followed by iron and steel (14.65 µg/L), petroleum (12.38 µg/L) printing (5.78 µg/L) and textile (3.76 µg/L) industries. The recovery values were achieved between 95 % and 99 %. The obtained results have established the appropriateness of the offered technique as a new useful method for the routine examination of Pb(II) in industrial wastes. In addition, the current method could be expansively used in the proficient removal and identification of other heavy metals contaminants from similar matrices. Further, the metal ions saturated bio-sorbents were used in the preparations of bricks and it was found to be a successful approach for heavy metals and agricultural waste management.     

Optimized determination of polybrominated diphenyl ethers by ultrasound‐assisted liquid–liquid extraction and high‐performance liquid chromatography

A method based on ultrasound‐assisted liquid–liquid extraction and high‐performance liquid chromatography has been optimized for the determination of six polybrominated diphenyl ether congeners. The optimal condition relevant to the extraction was first investigated, more than 98.7 ± 0.7% recovery was achieved with dichloromethane as extractant, 5 min extraction time, and three cycles of ultrasound‐assisted liquid–liquid extraction. Then multiple function was employed to optimize polybrominated diphenyl ether detection conditions with overall resolution and chromatography signal area as the responses. The condition chosen in this experiment was methanol/water 93:7 v/v, flow rate 0.80 mL/min, column temperature 30.0°C. The optimized technique revealed good linearity (R² > 0.9962 over a concentration range of 1–100 μg/L) and repeatability (relative standard deviation < 6.3%). Furthermore, the detection limit (S/N = 3) of the method were ranged from 0.02 to 0.13 μg/L and the quantification limit (S/N = 10) ranged from 0.07 to 0.35 μg/L. Finally, the proposed method was applied to spiked samples and satisfactory results were achieved. These results indicate that ultrasound‐assisted liquid–liquid extraction coupled with high‐performance liquid chromatography was effective to identify and quantify the complex polybrominated diphenyl ethers in effluent samples.     

In‐situ preparation of porous monolithic polymer inside hollow fiber as a micro‐solid phase extraction device for glucocorticoids in cosmetics

Glucocorticoids have a certain whitening effect on the skin. However, frequent and long‐term use of cosmetics including glucocorticoids is harmful to health. Herein, we proposed a novel micro‐solid phase extraction method for the detection of prednisolone acetate, prednisone, and prednisolone in cosmetics coupled with high‐performance liquid chromatography. In this method, porous monolithic polymer micro‐extraction bars were prepared by “one‐step, one‐pot” in situ photopolymerization combined with sacrificial support in hollow fiber under water atmosphere. The crucial factors such as pH of sample solution, extraction, and elution times that influence micro‐extraction were optimized and found to be 9.0, 2 h, and 32 min, respectively. Under the optimum experimental conditions, the linear range of the calibration curves were from 5.0 to 2000 µg/L with correlation coefficients (R²) between 0.9922 and 0.9996. The limit of detection and limit of quantification were 1.5 µg/L and 5.0 µg/L, respectively, and the recoveries were found to be in range of 69.0–113.3%. The analysis of precision for intraday and interday were less than 10.40 and 10.59%. The device has been successfully achieved photopolymerization under water atmosphere. The results indicated that this method is simple, accurate, and satisfactory for the pretreatment and determination of glucocorticoids in complex cosmetics samples.     

Dispersive solid‐phase extraction combined with dispersive liquid‐liquid microextraction for simultaneous determination of seven succinate dehydrogenase inhibitor fungicides in watermelon by ultra high performance liquid chromatography with tandem mass spectrometry

In this study, a simple and accurate sample preparation method based on dispersive solid‐phase extraction and dispersive liquid‐liquid microextraction has been developed for the determination of seven novel succinate dehydrogenase inhibitor fungicides (isopyrazam, fluopyram, pydiflumetofen, boscalid, penthiopyrad, fluxapyroxad, and thifluzamide) in watermelon. The watermelon samples were extracted with acetonitrile, cleaned up by dispersive solid‐phase extraction procedure using primary secondary amine, extracted and concentrated by the dispersive liquid‐liquid microextraction procedure with 1,1,2,2‐tetrachloroethane, and then analyzed by ultra high performance liquid chromatography with tandem mass spectrometry. The main experimental factors affecting the performance of dispersive solid‐phase extraction and dispersive liquid‐liquid microextraction procedure on extraction efficiency were investigated. The proposed method had a good linearity in the range of 0.1–100 µg/kg with correlation coefficients (r) of 0.9979–0.9999. The limit of quantification of seven fungicides was 0.1 µg/kg in the method. The fortified recoveries of seven succinate dehydrogenase inhibitor fungicides at three levels ranged from 72.0 to 111.6% with relative standard deviations of 3.4–14.1% (n = 5). The proposed method was successfully used for the rapid determination of seven succinate dehydrogenase inhibitor fungicides in watermelon.     

On‐chip electromembrane extraction of acidic drugs

In the present work, a new supported liquid membrane (SLM) has been developed for on‐chip electromembrane extraction of acidic drugs combined with HPLC or CE, providing significantly higher stability than those reported up to date. The target analytes are five widely used non‐steroidal anti‐inflammatory drugs (NSAIDs): ibuprofen (IBU), diclofenac (DIC), naproxen (NAX), ketoprofen (KTP) and salicylic acid (SAL). Two different microchip devices were used, both consisted basically of two poly(methyl methacrylate) (PMMA) plates with individual channels for acceptor and sample solutions, respectively, and a 25 µm thick porous polypropylene membrane impregnated with the organic solvent in between. The SLM consisting of a mixture of 1‐undecanol and 2‐nitrophenyl octyl ether (NPOE) in a ratio 1:3 was found to be the most suitable liquid membrane for the extraction of these acidic drugs under dynamic conditions. It showed a long‐term stability of at least 8 hours, a low system current around 20 µA, and recoveries over 94% for the target analytes. NPOE was included in the SLM to significantly decrease the extraction current compared to pure 1‐undecanol, while the extraction properties was almost unaffected. Moreover, it has been successfully applied to the determination of the target analytes in human urine samples, providing high extraction efficiency.     

Determination of four bisphenols in water and urine samples by magnetic dispersive solid‐phase extraction using a modified zeolite/iron oxide composite prior to liquid chromatography diode array detection

A novel approach is presented to determine four bisphenols in water and urine samples, employing magnetic dispersive solid‐phase extraction combined with liquid chromatography and diode array detection. A modified zeolite‐based magnetic composite was used as an efficient sorbent, combining the advantages of magnetic materials with the remarkable properties of zeolites. A multivariate optimization design was employed to optimize some experimental factors affecting magnetic dispersive solid‐phase extraction. The method was evaluated under optimized conditions (i.e., amount of sorbent, 50 mg; sample pH, unadjusted; NaCl concentration, 1.25%; extraction and elution time, 2 min; eluent solvent, ethanol; eluent solvent volume, 400 µL), obtaining good linearity with correlation coefficients ranging between 0.995 and 0.999 (N = 5) (from 2 to 250 µg/L for bisphenol A, bisphenol AP, and bisphenol P and from 5 to 250 µg/L for bisphenol AF). Method repeatability was assessed obtaining coefficients of variation between 3 and 11% (n = 6). Finally, the method was applied to spiked real samples, obtaining for water samples relative recoveries between 83 and 105%, and for urine samples between 81 and 108% for bisphenol A, bisphenol AP, and bisphenol AF, and between 47 and 59% for bisphenol P.     

Liquid chromatographic determination of trace levels of nitrophenols in water samples after dispersive magnetic solid phase extraction

An efficient and fast dispersive magnetic solid phase extraction method was developed using MIL‐101(Cr)/poly (mercaptobenzothiazole)@magnetite nanoparticles for the preconcentration and determination of nitrophenols in river and rain water samples. High‐performance liquid chromatography‐Ultraviolet instrument was applied for the analysis of target nitrophenols. The effect of several variables on the extraction performance was explored via design of experiment approach. Limits of detection and linear dynamic ranges were attained in the range of 0.05–0.10 µg/L and 0.2–250 µg/L, respectively. The enrichment factors were in the range of 317–363. The precision (n = 3) of dispersive magnetic solid phase extraction method was in the range of 5.3–6.8%. Eventually, the method was utilized for the analysis of target nitrophenols in river and rain water samples.     

Preparation of hydrophilic molecularly imprinted solid‐phase microextraction fiber for the selective removal and extraction of trace tetracyclines residues in animal derived foods

The present work reported a novel hydrophilic and selective solid‐phase microextraction fiber by improved multiple co‐polymerization method immobilization of tetracycline molecularly imprinted polymer on a stainless steel wire and directly coupled with high‐performance liquid chromatography for sensitive determination of trace tetracyclines residues in animal derived foods. The developed molecularly imprinted polymer coated solid‐phase microextraction fibers were characterized through scanning electron microscopy, Fourier transfer infrared spectroscopy, thermogravimetric analysis, and adsorption experiments, the fiber with cross‐linked and porous structure was observed and high thermal and chemical stability. The maximum adsorption capacity of this fiber with good selectivity reached 2.35 µg/mg in aqueous matrices, and showed good repeatability (relative standard deviation ≤ 6.6%, n = 5) and satisfying reproducibility between fiber to fiber (relative standard deviation ≤ 7.8%, n = 5). Under the optimized solid‐phase microextraction conditions, satisfactory linearity (5–1000 µg/L) and detection limits (0.38–0.72 µg/kg, S/N = 3) for all the tetracyclines were obtained. The practicality of this method was proved by adding tetracycline, oxytetracycline at three levels to milk, chicken, and fish samples with good recoveries of 77.3–104.4%.     

Development and application of SBA‐15 assisted electromembrane extraction followed by corona discharge ion mobility spectrometry for the determination of Thiabendazole in fruit juice samples

A new sample preparation method based on SBA‐15 assisted electromembrane extraction coupled with corona discharge ion mobility spectrometer was developed for the determination of Thiabendazole as a model basic pesticide in fruit juice samples. The addition of SBA‐15 in the supported liquid membrane in electromembrane extraction system not only can lead to enhancement of the effective surface area, but also introducing the negatively charged silanol groups into supported liquid membrane might improve migration of positively charged analytes toward the supported liquid membrane and finally into the acceptor solution. To investigate the effect of the presence of SBA‐15 in the supported liquid membrane on the extraction efficiency, a comparative study was carried out between the conventional electromembrane extraction and SBA‐15/electromembrane extraction methods. Under the optimized conditions, SBA‐15/electromembrane extraction method showed higher extraction efficiencies in comparison with conventional electromembrane extraction method. SBA‐15/electromembrane extraction method exhibited a low limit of detection (0.9 ng/mL), high preconcentration factor (167) and high recovery (83%). Finally, the applicability of SBA‐15/electromembrane extraction method was studied by the extraction and determination of Thiabendazole as a model basic pesticide in fruit juice samples.     

Resorcinol–formaldehyde aerogel coating for in‐tube solid‐phase microextraction of estrogens

Resorcinol–formaldehyde aerogel coating was in situ prepared on the surface of basalt fibers. The aerogel coating is uniformly modified onto basalt fibers, and it is very porous according to the characterization by using scanning electron microscopy. An extraction tube was prepared for in‐tube solid‐phase microextraction by placing the aerogel‐coated basalt fibers into a polyetheretherketone tube. To evaluate the extraction performance toward five estrogenic compounds, the tube was connected with high performance liquid chromatography, the important extraction and desorption conditions were investigated. An online analytical method for detection of estrogens was developed and presented low limits of detection (0.005–0.030 µg/L), wide linear ranges (0.017–20, 0.033–20, and 0.099–20 µg/L), good linearity (r > 0.9990), and satisfactory repeatability (relative standard deviation < 2.7%). The method was successfully applied to detect trace estrogens in real water samples (bottled pure water and bottled mineral water), satisfactory recoveries were ranged from 80 to 125% with two spiking levels of 2 and 6 µg/L.     

Distribution of sapogenins in morphological Medicago sativa L. parts: Comparison of various extraction techniques

Saponins in plant extracts were indirectly determined by estimation of the content of sapogenins. The first step of determination is extraction with high efficiency. One conventional extraction technique (maceration) and two modern ones (accelerated solvent extraction and supercritical fluid extraction) were compared. Methanol and ethanol were used as solvents or co‐solvents. The results were supported by statistical analysis. Saponins were extracted from leaves, roots, and sprouts of Medicago sativa. Acid hydrolysis, purification, and determination by high‐performance liquid chromatography with evaporative light scattering detector were used. The content of sapogenins was the highest in the roots. Smaller amounts of sapogenins were found in sprouts and the smallest ones in leaves. The main ingredient was medicagenic acid with mean concentration of 621.8 µg/g in roots, 456.7 µg/g in sprouts, and 471.3 µg/g in leaf extract. The highest content of sapogenins in extract was obtained after maceration with methanol; however, this method is nonselective in relation to biologically active compounds. Due to the possibility of using the obtained extracts with sapogenins in the cosmetic or pharmaceutical industry, the selection of extraction techniques and solvents is a very important aspect. Additionally, the chosen technique should be considered eco‐friendly and consistent with the assumptions of “green chemistry.”     

Ion‐pair‐based hollow‐fiber liquid‐phase microextraction combined with high‐performance liquid chromatography for the simultaneous determination of urinary benzene,toluene, and styrene metabolites

In the current study, a novel technique for extraction and determination of trans,trans‐muconic acid, hippuric acid, and mandelic acid was developed by means of ion‐pair‐based hollow fiber liquid‐phase microextraction in the three‐phase mode. Important factors affecting the extraction efficiency of the method were investigated and optimized. These metabolites were extracted from 10 mL of the source phase into a supported liquid membrane containing 1‐octanol and 10% w/v of Aliquat 336 as the ionic carrier followed by high‐performance liquid chromatography analysis. The organic phase immobilized in the pores of a hollow fiber was back‐extracted into 24 μL of a solution containing 3.0 mol/L sodium chloride placed inside the lumen of the fiber. A very high preconcentration of 212‐ to 440‐fold, limit of detection of 0.1–7 μg/L, and relative recovery of 87–95% were obtained under the optimized conditions of this method. The relative standard deviation values for within‐day and between‐day precisions were calculated at 2.9–8.5 and 4.3–11.2%, respectively. The method was successfully applied to urine samples from volunteers at different work environments. The results demonstrated that the method can be used as a sensitive and effective technique for the determination of the metabolites in urine.     

Hydrophobic deep eutectic solvent as a green extractant for high‐performance liquid chromatographic determination of tetracyclines in water samples

A green extractant, hydrophobic deep eutectic solvent was first introduced for extraction of tetracycline, oxytetracycline, and chlortetracycline from environmental water samples prior to high‐performance liquid chromatography determination. Deep eutectic solvents consist of methyltrioctylammonium chloride and various medium‐chain alcohols/acids, and are easy in preparation, low cost and toxicity, desirably biodegradable, and biocompatible. The overall time required for sample preparation was 6 min and the volume of organic solvent used for extraction was only 400 µL. Under the optimized extraction condition, the present method yielded low limit of detection (0.5–2.0 ng/mL), acceptable precision (relative standard deviations < 9.7%), good linearity from 2.0 to 500 ng/mL (r² ≥ 0.9991). This optimized procedure was applied for determination of tetracyclines in different water samples with desirable spiked recovery ranged from 77.5 to 87.6%. There is, therefore, a great potential to further expand application of the method for investigation of other ultra‐trace analyte(s) in environmental matrixes.