Air-assisted in situ deep eutectic solvent decomposition followed by the solidification of floating organic droplets-liquid-liquid microextraction method for extraction of azole antifungal drugs in biological samples prior to high-performance liquid chromatography

A free dispersive method, air-assisted in situ deep eutectic solvent decomposition followed by the solidification of floating organic droplets liquid-liquid microextraction was indicated in this study. This technique was utilized to simultaneously ascertain some azole antifungal drugs prior to high-performance liquid chromatography. In this research, a quasi-hydrophobic deep eutectic solvent was formed from tetrabutylammonium bromide and 1-dodecanol as an organic solvent at a 1:2 molar ratio. The synthesized deep decomposition in the sample solution caused in situ dispersion of extraction solvent and analytes. Air-assisted enhanced a dispersion condition in the sample solution. 1-Dodecanol as a green option was replaced with typical extraction solvents providing the advantages of a suitable freezing point near room temperature and low density. The effect of important analytical parameters on the extraction recovery of analytes was assessed. Under these optimal conditions, the limits of detection and the limits of quantitation determined were in the range of 0.5–2.8 and 1.5–9 μg/L, for water, urine and plasma samples, respectively. The intra-day and inter-day relative standard deviations (n = 5) were calculated to be 2.9–4.6 and 4.2–8.9%, respectively. The results represented the effectiveness of the developed method for the extraction and determination of analytes in biological samples.     

Temperature‐controlled liquid–liquid microextraction combined with high‐performance liquid chromatography for the simultaneous determination of diazinon and fenitrothion in water and fruit juice samples

A simple, environmentally benign, and rapid method based on temperature‐controlled liquid–liquid microextraction using a deep eutectic solvent was developed for the simultaneous extraction/preconcentration of diazinon and fenitrothion. The method involved the addition of deep eutectic solvent to the aqueous sample followed by heating the mixture in a 75°C water bath until the solvent was completely dissolved in the aqueous phase. Then, the resultant solution was cooled in an ice bath and a cloudy solution was formed. Afterward, the mixture was centrifuged and the enriched deep eutectic solvent phase was analyzed by high‐performance liquid chromatography with ultraviolet detection for quantification of the analytes. The factors affecting the extraction efficiency were optimized. Under the optimized extraction conditions, the limits of detection for diazinon and fenitrothion were 0.3 and 0.15 μg/L, respectively. The calibration curves for diazinon and fenitrothion exhibited linearity in the concentration range of 1–100 and 0.5–100 μg/L, respectively. The relative standard deviations for five replicate measurements at 10.0 μg/L level of analytes were less than 2.8 and 4.5% for intra‐ and interday assays, respectively. The developed method was successfully applied to the determination of diazinon and fenitrothion in water and fruit juice samples.     

Development of a stir bar sorptive extraction method coupled to solidification of floating droplets dispersive liquid–liquid microextraction based on deep eutectic solvents for the extraction of acidic pesticides from tomato samples

A stir bar sorptive extraction method coupled with deep eutectic solvent based solidification of floating organic droplets–dispersive liquid–liquid microextraction has been used for the simultaneous derivatization and extraction of some acidic pesticides in tomato samples. In this method, initially the analytes are adsorbed on a coated stir bar from tomato juice filled in a narrow tube. After extraction, the stir bar is removed and a water–miscible deep eutectic solvent is used to elute the analytes. Afterward, a derivatization agent and a water–immiscible deep eutectic solvent (as an extraction solvent) with melting point near to room temperature are added to the obtained eluant at µL–levels and the obtained mixture is rapidly injected into deionized water. Under the optimum conditions, the introduced method indicated high enhancement (1543–3353) and enrichment (2530–2999) factors, low limits of detection (7–14 ng/L) and quantification (23–47 ng/L), good linearity (r² ≥ 0.9982), and satisfactory repeatabilities (relative standard deviation ≤12% for intra– and inter–day precisions at a concentration of 100 ng/L of each analyte). Finally, the proposed method was applied in analysis of the analytes in tomato samples.     

preconcentration and determination of amoxicillin and ceftriaxone in hospital sewage using vortex-assisted liquid-phase microextraction based on the solidification of the deep eutectic solvent followed by HPLC–UV

In the present study, a new method for extraction and preconcentration of amoxicillin and ceftriaxone was used in hospitalised sewage samples, called vortex-assisted liquid-phase microextraction based on the solidification of deep eutectic solvent. Samples were analysed by high-performance liquid chromatography–ultraviolet detection after preparation and extraction. In this method, the new deep eutectic solvent is used as the extraction solvent, which is obtained from the combination of 1-decyl-3-methylimidazolium chloride and n-butanoic acid. The important advantages of this novel extraction solvent include material stability, low density and good freezing point near room temperature. Under the optimum conditions, enrichment factors are in the range of 164–172. Repeatability and reproducibility of the method based on seven replicate measurements of 50.0 µg L^?1 of the target analytes in analysed samples were in the range of 2.1–3.5% and 3.8–5.2%, respectively. The limit of detections and linearity are in the range of 0.005–0.10 and 3–600 µg L^?1, respectively. The method was successfully applied for the determination of amoxicillin and ceftriaxone in the real sewage samples. The relative recoveries of sewage samples spiked with amoxicillin and ceftriaxone are 91–107%.     

Development of a green miniaturized quick,easy, cheap,effective, rugged,and safe approach in tandem with temperature-assisted solidification of floating menthol droplet for analysis of multiclass pesticide residues in milk

A new green miniaturized quick, easy, cheap, effective, rugged, and safe approach was developed and used for the extraction of multiclass 16 pesticides in milk before gas chromatography analysis. The miniaturization of method reduced the consumption of chemical reagents and samples. Magnetic three-dimensional graphene was used as sorbent in the clean-up step. Choline chloride:lactic acid (1:2) natural deep eutectic solvent was used as desorption solvent. Temperature-assisted solidification of floating menthol drop was executed for preconcentration of analytes. The method parameters including sorbent, desorption solvent, sorption and desorption times, menthol amount, pH, and ionic strength were optimized. The limit of quantification and linear range were 0.03–0.38 and 0.03–250 μg/kg, respectively. The accuracy was assessed by recovery evaluation at the spike levels of 50 and 100 μg/kg, in the range of 61–119%, with relative standard deviations within 2.1–18.2%. The method was applied to the analysis of pasteurized low and high-fat bovine milk, and various pesticide residues were detected in the concentrations range of 1.24–4.68 μg/kg. Finally, the greenness of the procedure was evaluated using the Analytical Eco-Scale. This work represents the first application of hybrid miniaturized extraction/preconcentration using a natural deep eutectic solvent and menthol to analyze pesticides.     

Analysis of hormone antagonists in clinical and municipal wastewater by isotopic dilution liquid chromatography tandem mass spectrometry

A comprehensive method was developed for the simultaneous trace analysis of ten hormone antagonist pharmaceuticals (raloxifene, exemestane, letrozole, anastrozole, mifepristone, finastride, tamoxifen, N-desmethyltamoxifen, clomiphene, and toremifene) in municipal sewage and hospital wastewater samples. The target compounds were firstly extracted using an Oasis HLB cartridge, followed by purification by an aminopropyl cartridge, and were then analyzed by liquid chromatography electrospray ionization tandem mass spectrometry in positive ion mode. The recoveries for the analytes based on internal standard calibration in different test matrices ranged from 67.6 to 118.6% (with the exception of mifepristone in clinical wastewater samples), with relative standard deviations less than 20%. The method quantification limits of the ten pharmaceuticals were in the range 0.10–2.0 ng/L. Excluding exemestane and N-desmethyltamoxifen, eight drugs were detected at 0.20–195.0 ng/L in hospital wastewater and municipal wastewater samples from Beijing.     

Combination of a modified quick,easy, cheap,efficient, rugged,and safe extraction method with a deep eutectic solvent based microwave‐assisted dispersive liquid–liquid microextraction: Application in extraction and preconcentration of multiclass pesticide residues in tomato samples

In this study, a new two–step extraction procedure based on the combination of a modified quick, easy, cheap, effective, rugged, and safe extraction method with a deep eutectic solvent based microwave‐assisted dispersive liquid–liquid microextraction has been developed for the extraction of multiclass pesticides in tomato samples before their analysis by gas chromatography with flame ionization detection. In this method, initially, an aliquot of tomato is crushed and diluted with deionized water. The mixture is then passed through a filter paper and its residue and aqueous phase are separated. Afterwards, acetonitrile as an extraction/disperser solvent is passed through the filter paper containing the refuse. The analytes remained in the refuse are extracted into the acetonitrile and then the obtained extract is mixed with a deep eutectic solvent. The obtained mixture is injected into the tomato juice and placed in a microwave oven for 15 s. Consequently, a cloudy state is formed and the extractant containing the analytes are sedimented at the bottom of the tube after centrifugation. Finally, 1 μL of the sedimented phase is removed and injected into the separation system. Under the optimum conditions, limits of detection and quantification were in the ranges of 0.42–0.74 and 1.4–2.5 ng/g, respectively.     

Rapid Determination of DDT and Its Metabolites in Environmental Water Samples with Mixed Ionic Liquids Dispersive Liquid–Liquid Microextraction Prior to HPLC-UV

In this paper, a novel mixed ionic liquids-dispersive liquid–liquid microextraction method was developed for rapid enrichment and determination of environmental pollutants in water samples. In this method, two kinds of ionic liquids, hydrophobic ionic liquid and hydrophilic ionic liquid, were used as extraction solvent and disperser solvent, respectively. DDT and its metabolites were used as model analytes and high-performance liquid chromatography with ultraviolet detector for the analysis. Factors that may affect the extraction recoveries, such as type and volume of extraction solvent (hydrophobic ionic liquid) and disperser solvent (hydrophilic ionic liquid), extraction time, sample pH and ionic strength, were investigated and optimized. Under the optimum conditions, the linear range was 1–100 μg L⁻¹, limits of detection could reach 0.21–0.49 μg L⁻¹, and relative standard deviation was 6.01–8.48 % (n = 7) for the analytes. Satisfactory results were achieved when the method was applied to analyze the target pollutants in environmental water samples with spiked recoveries over the range of 85.7–106.8 %.

     

Development of a high‐performance liquid chromatography method with fluorescence detection for the routine quantification of tamoxifen,endoxifen and 4‐hydroxytamoxifen in plasma from breast cancer patients

To date, several methods for the quantification of tamoxifen and its metabolites have been developed, most of which employ liquid chromatography tandem–mass spectrometry (LC–MS/MS). These methods are highly sensitive and reproducible, but are also time‐consuming and require expensive equipment; one of their main disadvantages is matrix ionization effects. A more viable option, particularly in developing countries, is high‐performance liquid chromatography coupled with UV or fluorescence detection. We developed and validated a method for simultaneous quantification of tamoxifen, endoxifen and 4‐hydroxytamoxifen based on high‐performance liquid chromatography with fluorescence detection in a reverse‐phase column. The method is rapid (16 min plus 5 min of column re‐equilibrium), accurate (80–100%) and precise (0.23–6.00%), and does not require any additional irradiation process. Sample pretreatment consists of protein precipitation with acetonitrile under alkaline conditions, employing only 200 μL plasma. The validated method's wide range allowed quantification of steady‐state levels in patients under standard tamoxifen treatment (20 mg/day). This assay is ready for application in clinical studies and routine quantification of tamoxifen, endoxifen and 4‐hydroxytamoxifen in healthcare institutions.     

Development and validation of UPLC tandem mass spectrometry assay for separation of a phase II metabolite of ramipril using actual study samples and its application to a bioequivalence study

In this paper, we present a validated UPLC‐MS/MS assay for determination of ramipril and ramiprilat from human plasma samples. The assay is capable of isolating phase II metabolites (acylglucornides) of ramipril from in vivo study samples which is otherwise not possible using conventional HPLC conditions. Both analytes were extracted from human plasma using solid‐phase extraction technique. Chromatographic separation of analytes and their respective internal standards was carried out using an Acquity UPLC BEH C₁₈ (2.1 × 100 mm), 1.7 µm column followed by mass spectrometric detection using an Waters Quattro Premier XE. The method was validated over the range 0.35–70.0 ng/mL for ramipril and 1.0–40.0 ng/mL for ramiprilat. Copyright © 2010 John Wiley & Sons, Ltd.     

Development of new extraction method based on liquid–liquid–liquid extraction followed by dispersive liquid–liquid microextraction for extraction of three tricyclic antidepressants in plasma samples

In the present study, a new extraction method based on a three–phase system, liquid–liquid–liquid extraction, followed by dispersive liquid–liquid microextraction has been developed and validated for the extraction and preconcentration of three commonly prescribed tricyclic antidepressant drugs – amitriptyline, imipramine, and clomipramine – in human plasma prior to their analysis by gas chromatography–flame ionization detection. The three phases were an aqueous phase (plasma), acetonitrile and n–hexane. The extraction mechanism was based on the different affinities of components of the biological sample (lipids, fatty acids, pharmaceuticals, inorganic ions, etc.) toward each of the phases. This provided high selectivity toward the analytes since most interferences were transferred into n–hexane. In this procedure, a homogeneous solution of the aqueous phase (plasma) and acetonitrile (water–soluble extraction solvent) was broken by adding sodium sulfate (as a phase separating agent) and the analytes were extracted into the fine droplets of the formed acetonitrile. Next, acetonitrile phase was mixed with 1,2–dibromoethane (as a preconcentration solvent at microliter level) and then the microextraction procedure mentioned above was performed for further enrichment of the analytes. Under the optimum extraction conditions, limits of detection and lower limits of quantification for the analytes were obtained in the ranges of 0.001–0.003 and 0.003–0.010 μg mL⁻¹, respectively. The obtained extraction recoveries were in the range of 79–98%. Intra– and inter–day precisions were < 7.5%. The validated method was successfully applied for determination of the selected drugs in human plasma samples obtained from the patients who received them.     

Development of a methodology to quantify tamoxifen and endoxifen in breast cancer patients by micellar liquid chromatography and validation according to the ICH guidelines

A simple micellar liquid chromatographic procedure is described to determine tamoxifen and endoxifen in plasma. For the analysis, tamoxifen and endoxifen solutions were diluted in water and UV-irradiated for 20 min to form the photocycled derivative with a phenanthrene core which shows intense fluorescence. Samples were then directly injected, thus avoiding long extraction and experimental procedures. The resolution from the matrix was performed using a mobile phase containing 0.15 mol L⁻¹ SDS-7% n-butanol at pH 3, running at 1.5 mL min⁻¹ through a C18 column at 40 °C. Detection was carried out by fluorescence, and the excitation and emission wavelengths were 260 and 380 nm, respectively. The chromatographic analysis time was 20 min. The analytical methodology was validated following the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines. The response of the drugs in plasma was linear in the 0.5-15 μg mL⁻¹ range, with r² > 0.99. Accuracy and precision were <14% in both cases. Limits of detection and quantification (ng mL⁻¹) in plasma were 75 and 250 for endoxifen, and 50 and 150 in tamoxifen. The method developed herein does not show interferences by endogenous compounds. Finally the analytical method was used to determine the amount of tamoxifen and endoxifen in several plasma samples of breast cancer patients from a local hospital.     

Development of deep eutectic solvent–based microwave-assisted extraction combined with temperature controlled ionic liquid–based liquid phase microextraction for extraction of aflatoxins from cheese samples

In this study, for the first time, a deep eutectic solvent-based microwave-assisted extraction was combined with ionic liquid–based temperature controlled liquid phase microextraction for the extraction of several aflatoxins from cheese samples. Briefly, the analytes are extracted from cheese sample (3 g) into a mixture of 1.5 mL choline chloride:ethylene glycol deep eutectic solvent and 3.5 mL deionized water by exposing to microwave irradiations for 60 s at 180 W. The liquid phase was taken and mixed with 55 μL 1-hexyl-3-methylimidazolium hexafluorophosphate. By cooling the solution in the refrigerator centrifuge, a turbid state was obtained and the analytes were extracted into the ionic liquid droplets. The analytes were determined by high-performance liquid chromatography equipped with fluorescence detector. Low limits of detection (9–23 ng kg^–1) and quantification (30–77 ng kg^–1), high extraction recovery (66%–83%), acceptable enrichment factor (40–50), and good precision (relative standard deviations ≤ 5.2%) were obtained using the offered approach. These results reveal the high extraction capability of the method for determination of aflatoxins in the cheese samples. In this method, there was no need for organic solvents and it can be considered as green extraction method.     

Simultaneous analysis of oral anticancer drugs for renal cell carcinoma in human plasma using liquid chromatography/electrospray ionization tandem mass spectrometry

An analytical method using high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry has been developed and validated for simultaneous measurement of four tyrosine kinase inhibitors used for renal cell carcinoma and their metabolites in human plasma. Despite their similar structures, it is difficult to measure plasma levels of these compounds simultaneously using optimal MS parameters for each compound because a quantitative range exceeding 50,000‐fold is required. To overcome this problem, we used a linear range shift technique using in‐source collision‐induced dissociation. Linearity ranges of sorafenib, sorafenib N‐oxide, sunitinib, N‐desethyl sunitinib, axitinib and pazopanib were 100–10,000, 10–1,000, 1–100, 1–100, 1–100 and 500–50,000 ng/mL, respectively. The intra‐ and inter‐day precision and accuracy were high, and coefficients of variation and relative error were <10.3% and within ±11.8%, respectively. The matrix effects of all analytes ranged from 87.7 to 114.8%. Extraction recoveries and overall recoveries showed small extraction loss (<15.0%) for all analytes. Moreover, all cancer patient samples used in this study were successfully quantified and fell within the linear range of measurement. Therefore, this novel analytical system using in‐source collision‐induced dissociation has sufficient performance to measure plasma concentrations of these four tyrosine kinase inhibitors and their metabolites for therapeutic drug monitoring.     

Three‐phase hollow‐fiber liquid‐phase microextraction based on deep eutectic solvent as acceptor phase for extraction and preconcentration of main active compounds in a traditional Chinese medicinal formula

A three‐phase hollow‐fiber liquid‐phase microextraction based on deep eutectic solvent as acceptor phase was developed and coupled with high‐performance capillary electrophoresis for the simultaneous extraction, enrichment, and determination of main active compounds (hesperidin, honokiol, shikonin, magnolol, emodin, and β,β′‐dimethylacrylshikonin) in a traditional Chinese medicinal formula. In this procedure, two hollow fibers, impregnated with n‐heptanol/n‐nonanol (7:3, v/v) mixture in wall pores as the extraction phase and a combination (9:1, v/v) of methyltrioctylammonium chloride/glycerol (1:3, n/n) and methanol in lumen as the acceptor phase, were immersed in the aqueous sample phase. The target analytes in the sample solution were first extracted through the organic phase, and further back‐extracted to the acceptor phase during the stirring process. Important extraction parameters such as types and composition of extraction solvent and deep eutectic solvent, sample phase pH, stirring rate, and extraction time were investigated and optimized. Under the optimal conditions, detection limits were 0.3–0.8 ng/mL with enrichment factors of 6–114 for the analytes and linearities of 0.001–13 μg/mL (r² ≥ 0.9901). The developed method was successfully applied to the simultaneous extraction and concentration of the main active compounds in a formula of Zi‐Cao‐Cheng‐Qi decoction with the major advantages of convenience, effectiveness, and environmentally friendliness.     

Deep eutectic solvent based gas‐assisted dispersive liquid‐phase microextraction combined with gas chromatography and flame ionization detection for the determination of some pesticide residues in fruit and vegetable samples

In this study, a gas‐assisted dispersive liquid‐phase microextraction method using a deep eutectic solvent as the extraction solvent combined with gas chromatography and flame ionization detection was developed for the extraction and determination of some pesticide residues in vegetable and fruit juice samples. In this method, choline chloride and 4‐chlorophenol at a molar ratio of 1:2 were mixed. By heating and vortexing, a clear, water‐immiscible, and homogeneous liquid was formed. The obtained deep eutectic solvent was added to an aqueous solution of the analytes in a conical test tube. Air was bubbled into the aqueous solution and a cloudy solution was obtained. During this step, the analytes were extracted into the fine droplets of the extraction solvent. After centrifugation, an aliquot of the settled phase was injected into the separation system. Under the optimum extraction conditions, enrichment factors, and extraction recoveries were obtained in the ranges of 247–355 and 49–71%, respectively. The obtained values for the limits of detection and quantification were in the ranges of 0.24–1.4 and 0.71–4.2 μg/L, respectively. The proposed method is simple, fast, efficient, and inexpensive.     

Deep eutectic solvent-based modified quick,easy, cheap,effective, rugged,and safe extraction combined with solidification of floating organic droplet-dispersive liquid–liquid microextraction of some pesticides from canola oil followed by gas chromatography analysis

Herein, a modified quick, easy, cheap, effective, rugged, and safe extraction was developed based on deep eutectic solvent for the extraction of several pesticides from canola oil samples. In this work, first, different sorbents were selected to remove the sample interferences, and the composition of the sorbents was optimized by simplex centroid design. The extracted analytes were more concentrated by solidification of floating deep eutectic solvent droplet-dispersive liquid–liquid microextraction. Low limits of detection (0.15–0.23 ng/g) and quantification (0.49–0.76 ng/g), high extraction recoveries (74–87%) and enrichment factors (224–263), and good repeatability (relative standard deviation equal to or less than 5.1 and 4.7% for intra- and interday precisions, respectively) were achieved using the proposed method. The suggested approach was used for the quantification of the analytes in different canola oil samples. Additionally, the effects of microwave irradiations exposure and sonication in decontamination of the samples were evaluated. In this method, there was no need for centrifugation and toxic solvents. Also, effective extraction of the analytes and minimizing interferences were achieved through the use of various sorbents.     

UPLC‐MS/MS method for the determination of tobacco‐specific biomarker NNAL,tamoxifen and its main metabolites in rat plasma

Cigarette smoke is known to interact with tamoxifen‐metabolizing enzymes and transporters and potentially affect its treatment outcome. 4‐(N‐ nitrosomethylamino)‐1‐(3‐pyridyl)‐1‐butanol (NNAL) is an important metabolite of 4‐(methylnitro‐samino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) because it is frequently used as a biomarker to assess human smoke exposure. In order to study the potential pharmacokinetic interaction between cigarette smoke and tamoxifen in rats a UPLC‐MS/MS method for the simultaneous determination of NNAL and tamoxifen along with its metabolites in rat plasma has been developed and validated. Analytes were extracted with methanol and separated on a HSS T3 column by a gradient elution with the mobile phase consisting of acetonitrile and water. The lower limits of quantitation ranged from 0.05 to 0.62 ng/mL. Precisions showed RSD <15.8% and accuracy in the range 80.6–116.0%. Mean analyte recoveries ranged from 76.9 to 108.4%. The method was successfully applied to study the effects of cigarette smoke condensate (CSC), NNK and benzo(a)pyrene pre‐treatment on the pharmacokinetics of tamoxifen and its metabolites in rats. Significant effects of CSC, NNK, benzo(a)pyrene were observed on pharmacokinetics of tamoxifen and its metabolites. We also found that plasma NNAL levels are statistically significant correlated with plasma 4‐hydroxy‐tamoxifen and endoxifen.     

Quantification of tamoxifen and metabolites and soy isoflavones in human plasma using liquid chromatography with electrospray ionization tandem mass spectrometry

Tamoxifen is an important estrogen receptor antagonist used successfully for the treatment and prevention of breast cancer. The use of complementary and alternative medicines is an increasingly popular means for patients to participate in their own health care, and soy products, which contain phytoestrogens, have been widely promoted for possible beneficial effects on menopausal symptoms. The possibility that soy isoflavones could reduce tamoxifen efficacy has been demonstrated in animal models of post-menopausal breast cancer, but the occurrence of such an effect in women has not been explored. This paper describes the development and validation of a sensitive method using solid-phase extraction and isotope dilution liquid chromatography/tandem mass spectrometry with multiple reaction monitoring for the concurrent analysis of the major soy isoflavones (genistein and daidzein), an important metabolite of daidzein (equol), tamoxifen, and its important metabolites (4-hydroxytamoxifen, N-desmethyltamoxifen, and 4-hydroxy-N-desmethyltamoxifen or "endoxifen") in the serum of rats and women. The limits of quantification achieved are sufficient to determine accurately and precisely the concentrations of all of these analytes in women consuming soy foods and/or therapeutic doses of tamoxifen at levels consistent with modulation of estrogen receptor-mediated functions. These procedures enable future investigations of the possible impact of diet on the outcome of breast cancer therapy.     

Deep eutectic solvent based homogeneous liquid–liquid extraction coupled with in‐syringe dispersive liquid–liquid microextraction performed in narrow tube; application in extraction and preconcentration of some herbicides from tea

A homogeneous liquid‐liquid extraction performed in narrow tube coupled to in–syringe‐dispersive liquid‐liquid microextraction based on deep eutectic solvent has been developed for the extraction of six herbicides from tea samples. In this method, sodium chloride as a separation agent is filled into the narrow tube and the tea sample is placed on top of the salt. Then a mixture of deionized water and deep eutectic solvent (water miscible) is passed through the tube. In this procedure, the deep eutectic solvent is realized as tiny droplets in contact with salt. By passing the droplets from the tea layer placed on the salt layer, the analytes are extracted into them. After collecting the solvent as separated layer, it is mixed with another deep eutectic solvent (choline chloride/butyric acid) and the mixture is dispersed into deionized water placed in a syringe. After adding acetonitrile to break up the cloudy state, the collected organic phase is injected into gas chromatography‐mass spectrometry. Under optimal conditions, limits of detection and quantification in the ranges of 2.6–8.4 and 9.7–29 ng/kg, respectively, were obtained. The extraction recoveries and enrichment factors in the ranges of 70–89% and 350–445 were obtained, respectively.