Volume Of Disperser Solvents Research Articles

Solvent-Focused Gas Chromatographic Determination of Thymol and Carvacrol Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction through Solidifying Floating Organic Droplets (USA-DLLME-SFO).

An ultrasound-assisted dispersive liquid-liquid microextraction by solidifying floating organic droplets, coupled to a form of temperature-programmed gas chromatography flame ionization detection, has been developed for the extraction and determination of thymol and carvacrol. This method utilizes undecanol as the extraction solvent, offering advantages such as facilitating phase transfer through solidification and enhancing solvent-focusing efficiency. The optimal gas chromatography conditions include a sample injection volume of 0.2 µL, a split ratio of 1:10, and a flow rate of 0.7 mL min-1. The extraction conditions entail an extraction solvent volume of 20 µL, a disperser solvent (acetone) volume of 500 µL, pH 7.0, 7.0% NaCl (3.5 M), a sample volume of 5.0 mL, an ultrasound duration of 10 min, and a centrifuge time of 7.5 min (800 rpm). These conditions enable the achievement of a high and reasonable linear range of 3.5 to 70. 0 μg mL-1 for both thymol and carvacrol. The detection limits are found to be 0.95 and 0.89 μg mL-1, respectively, for thymol and carvacrol. The obtained relative standard deviations, 2.7% for thymol and 2.6% for carvacrol, demonstrate acceptable precision for the purpose of quantitative analysis.

Sensitive quantification of acetochlor and metolachlor in water using Taguchi-optimized DLLME coupled with high-performance liquid chromatography

In this study, we developed a method that is sensitive, simple, and environmentally friendly for quantifying acetochlor and metolachlor. This method combines vortex-assisted dispersive liquid–liquid microextraction (DLLME) with high-performance liquid chromatography (HPLC). HPLC operating parameters and extraction parameters for direct and post-extraction analyses of acetochlor and metolachlor were optimized by employing the Taguchi experimental design method. The optimized HPLC parameters for acetochlor and metolachlor were 1.00 mL/min and 1.2 mL/min flow rate, 40 °C column temperature, and 70/30 (ACN/Water) and 80/20 (ACN/Water) at 210 and 230 nm wavelengths, respectively, for the direct injection method. For the DLLME procedure, 1,2-dichloroethane extraction solvent type, acetonitrile, and methanol dispersive solvent type, 400 µL and 300 µL extraction solvent volumes, and 1.0 mL dispersive solvent volume were the optimized DLLME extraction parameters, respectively. The developed and optimized methods for acetochlor and metolachlor analyses exhibited satisfactory validation results, with excellent linearity, indicated by R2 values greater than 0.99. The limit of detection (LOD) and the limit quantification (LOQ) levels of acetochlor and metolachlor were 28.96 to 31.25 µg/L, and 86.87 to 93.75 µg/L for direct injection, and 1.15 to 1.24 µg/L and 3.47 to 3.75 µg/L for post-extraction, respectively. The DLLME recovery values were within the range of 82.6–99.2 % (relative standard deviations-RSD: 4.47–10.13 %) for acetochlor and 91.1–103.4 % (4.31–7.96 %) for metolachlor. Repeatability and reproducibility results (n = 10) of direct injection and post-extraction methods for fortified acetochlor and metolachlor samples displayed very high precision lower than 2 % RSD.

Determination of aflatoxins in rice from Penang, Malaysia by dispersive liquid–liquid micro-extraction and LC–MS/MS

Rice is one of the crops cultivated in Malaysia, and it is the main diet for most of the population. In this study, dispersive liquid–liquid micro-extraction (DLLME) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) were used to develop, optimise and validate a reliable, easy-to-use and quick approach to detect aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). The extraction recoveries in DLLME were enhanced by the addition of 5% salt, utilising chloroform as the extraction solvent and acetonitrile as the dispersive solvent. The DLLME parameters – the extraction solvent volume, salt concentration and dispersive solvent volume were optimised with Box–Behnken design (BBD) and response surface methodology (RSM). Under optimised experimental conditions, excellent linearity was obtained with a limit of detection (LOD) ranging from 0.125 to 0.25 ng g−1, a limit of quantitation (LOQ) ranging from 0.25 to 0.3 ng g−1 and a correlation value (R 2) of 0.990. The matrix effects were between −11.1% and 19.9%, and recoveries ranged from 87.4% to 117.3%. The optimised and validated method was used effectively to assess aflatoxins contamination in 20 commercial rice samples collected from local supermarkets in Penang, Malaysia. AFB1 was detected at 0.41–0.43 ng g−1 in two rice samples, below the regulatory limit.

A Cyanoalkyl Silicone GC Stationary-Phase Polymer as an Extractant for Dispersive Liquid–Liquid Microextraction

In this work, three cyanoalkyl silicone GC stationary-phase polymers, namely OV-105, OV-225, and OV-275, were investigated as potential extractants for dispersive liquid–liquid microextraction (DLLME). The OV-225 polymer (cyanopropylmethyl-phenylmethylsilicone) exhibited the cleanest chromatographic background and was extensively studied. The proposed polymer was tested through the DLLME of four non-steroidal anti-inflammatory drugs from aqueous samples, followed by HPLC separation with UV detection at 230 nm. To achieve the maximum enrichment, the experimental conditions that influence the DLLME process were optimized using one-factor-at-a-time and design-of-experiment (DoE) approaches. The extraction variables (polymer mass, dispersive solvent volume, buffer pH, and mixing time) were screened by implementing a two-level full factorial design (FFD). Significant variables were fine-tuned using response surface methodology based on a face-centered central composite design (CCD). The optimum conditions were 10 mg of polymer (extraction medium); 50 µL of tetrahydrofuran (dispersive solvent); 100 µL of phosphate buffer pH 2.75 ([PO43−] = 100 mM); and 3 min of vortex mixing. The addition of salt had a minimal effect on the enrichment factors. In the optimum conditions, enrichment factors up to 46 were achieved using 1.5 mL samples. Calibration curves exhibited correlation coefficients > 0.999 using 4-pentylbenzoic acid as an internal standard. The limits of quantitation were 5 ng/mL for naproxen, 10 ng/mL for diflunisal, 25 ng/mL for indomethacin, and 75 ng/mL for ibuprofen. The analysis of spiked tap water samples showed adequate relative recoveries and precision. In conclusion, the proposed polymer (OV-225) is a potential greener alternative to traditional organic extractants used in DLLME.

Ultrasound- and Vortex-Assisted Dispersive Liquid-Liquid Microextraction of Parabens from Personal Care Products and Urine, Followed by High-Performance Liquid Chromatography.

Parabens, which are p-hydroxybenzoic acid esters, are used as preservatives in personal care products, pharmaceuticals, and food because of their antimicrobial activity. However, they are also classified as suspected endocrine disruptors and carcinogens. In the present study, we aimed to optimize an ultrasound and vortex-assisted dispersive liquid-liquid microextraction (DLLME) procedure for the simultaneous extraction of methyl, ethyl, isopropyl, propyl, isobutyl, and butyl parabens from personal care products and urine. The extraction solvent type, extraction solvent volume, disperser solvent volume, sodium chloride concentration, ultrasonication time, and vortex application time were evaluated to obtain optimum recoveries by ultrasound and vortex-assisted DLLME. Parabens were detected using a validated high performanc-liquid chromatography (HPLC) method with fluorescence detection. Method validation was performed by examining linearity, the limit of detection, limit of quantification, accuracy, and precision. The limits of detection and quantification of the HPLC method were between 0.09-0.18 μg/mL and 0.28-0.54 μg/mL, respectively. Precision was examined as the relative standard deviation, which was 0.22-1.81% and 1.12-2.03% for intra- and interday studies. Recovery percentages were higher than 96.00%. Samples of two paraben-free personal care products and synthetic urine were spiked with the analyses at 0.02 μg/mL and were successfully analyzed using the developed procedure with recovery values higher than 82.00%. The proposed procedure provided quantification of selected parabens at 20 ng/mL in analyzed personal care products and urine matrices with good precision and accuracy.

Mechanistic insights into the roles of precursor content, synthesis time, and dispersive solvent in maximizing supercapacitance of N-rGO sheets

Graphene oxide (GO) sheets were prepared using the improved Hummers’ method, followed by simultaneous reduction and nitrogen doping using an easy solvothermal route to obtain Nitrogen-doped reduced graphene oxide (N-rGO) sheets. The amount of N-doping was controlled using the different amounts of GO and Urea, keeping the ratio of the two (1:3) fixed. Here, we examined several variations in synthesis parameters, viz. change in precursor content, variation in synthesis time, and volume of dispersive solvent. The N-rGO sample prepared with 250 mg GO and 750 mg urea at 24-hour synthesis time in 80 ml dispersive solvent exhibits a superlative specific capacitance of 1244 F/g at 0.5 A/g using 3-electrode measurements in an acidic medium. The high value can be understood via the synergistic roles of optimum defects, degree of reduction, and types of N-environments. The symmetric 2-electrode device prepared by depositing the synthesized material onto carbon cloth exhibits supercapacitance of 635 F/g at 1 A/g current density and high cyclic constancy with capacitive retention of ∼ 96% after 10000 charge-discharge cycles. Our work provides critical mechanistic insights on the complex intermingling of an optimum N-content, the relative amount of the different N-environments, degree of reduction, and disorder to generate a high specific capacitance, remarkably better than previously reported works on similar materials. Notably, a relatively high graphitic-N, with moderate surface N-content (4.64%) and a moderate degree of reduction, leads to this higher specific capacitance.

A green ternary polymeric deep eutectic solvent used in dispersive liquid-liquid microextraction technique for isolation of multiclass pesticides in fruit juice samples

A green dispersive liquid-liquid microextraction procedure based on a ternary polymeric hydrophobic deep eutectic solvent (DES) for monitoring multi-residue pesticides in eleven various fruit juices was developed before Gas Chromatography coupled with micro-Electron Capture Detector (GC-µECD). Six ternary polyethylene glycol (PEG)-based DESs were synthesized, and their extraction efficiency was evaluated. Among these DESs, [thymol]:[polyethylene glycol]:[acetic acid] (1:2:2) showed the highest signal intensity. Moreover, three other binary PEG-based DESs and a non-polymeric DES were also synthesized and compared to the previous DES. The extraction yield obtained by polymeric one was much higher than non-polymeric. Some significant parameters influencing the extraction efficiency including the type and volume of DES (extraction solvent), disperser solvent, pH, and ionic strength were optimized as follows: [Thy]:[PEG]:[HOAc] (1:2:2), 400 µL of DES, ACN as disperser solvent (700 µL), no pH adjustment and no salt addition. The DES was characterized by ATR-FTIR and (1H and 13C) NMR spectroscopy. Under the optimized conditions, the limits of quantification, the linear ranges and extraction recovery were 0.009–0.182 µgL−1 0.003–50.0 µgL−1, 67.9–108.4%, respectively. The enrichment factors were 11–170. Intra-day and inter-day RSDs% were 1.4–5.1% and 2.0–12.6%, respectively. This method was applied for analyzing pesticide residues in eleven fruit juices, and the pre-concentration factor and relative extraction recoveries were in the range of 12–169 and 71–108%, respectively.

A green deep eutectic solvent based dispersive liquid-liquid microextraction for the quantitative analysis of 21 polychlorinated biphenyl metabolites in food of animal origin using injector port silylation-gas chromatography-tandem mass spectrometry

An analytical method was developed for the quantitative determination of 21 polychlorinated biphenyls (PCBs) metabolites (17 were -OH, 1 -MeO, and 3 were MeSO2) in foods of animal origin using deep eutectic solvent (DES) based dispersive liquid-liquid microextraction followed by injector port silylation-gas chromatography-tandem mass spectrometry. The type of DES (thymol: camphor, 1:1 molar ratio) and optimum volume of DES (300 µL), pH (7.0), and disperser solvent (acetonitrile) were optimized to attain the maximum extraction efficiency. The limit of detection, limit of quantification, and percent recovery were found to be in the range of 0.12–0.23 ng/mL, 0.40–0.76 ng/mL, and 80.1–111.4%, respectively. The expanded uncertainty was observed to be in the range of 7.2–22.8% for the targeted analytes. The proposed method was applied to real food samples (milk, meat, fish, and egg) and the levels were found to be in the range of 0.64–32.14 ng/g. This is first of its kind method using green solvent based method for the analysis of PCB metabolites (-OH, MeO, and MeSO2) and will find extensive application in routine testing for foods of animal origin.

Development of microextraction methods for the determination of sulfamethoxazole in water and biological samples: modelling, optimization and verification by central composite design

This study aimed to preconcentration of sulfamethoxazole (SMX) in water and biological samples. Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and ultrasound-assisted dispersive solid-phase microextraction (UA-DSPME) methods paired with spectrophotometry were applied to extraction and preconcentration of SMX. ZnFe2O4 nanoparticles were prepared as adsorbent in UA-DSPME method by hydrothermal method. The scanning electron microscopy (SEM) technique showed that the adsorbent had symmetrical, bullet-shaped particles with uniform size. The results of the X-ray diffraction (XRD) showed the successful synthesis of the ZnFe2O4 nanoparticles. Effective parameters in extraction, including ultrasonication time, disperser solvent volume, adsorbent amount, extraction solvent volume, eluent volume, and pH were investigated and optimized. The practical and optimal conditions of the process were determined by the central composite design (CCD). The optimal conditions were 0.024 g of adsorbent, 535 µL of disperser solvent volume, 7.5 min of ultrasonication time, 235 µL of eluent volume, pH of 5, and 185 µL of extraction solvent volume. Linear ranges and detection limits were 20–1,200 μg L−1 and 6 μg L−1 for UA-DSPME and 10–800 μg L−1 and 3 μg L−1 for UA-DLLME. Relative standard deviation (RSD) of less than 4% were obtained for UA-DSPME and UA-DLLME methods. The reusability showed that the ZnFe2O4 adsorbent could extract SMX up to five cycles of adsorption/desorption without significant reduction in its efficiency. Also, interference studies showed that the presence of different cations and anions did not significantly interfere in the extraction of SMX. The outcomes of real-time samples analysis showed that the extraction of SMX for both methods was in the range of 92.44%–99.12%. The results showed the developed methods are simple, sensitive, and suitable for SMX preconcentration in environmental water and biological samples.

Ionic liquid-based dispersive liquid-liquid microextraction of anthelmintic drug residues in small-stock meat followed by LC-ESI-MS/MS detection.

An ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) of 20 anthelmintic drugs followed and detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed, optimized, and validated. The parameters affecting the anthelmintic extraction efficiencies such as selection of extraction solvent (ionic liquids), selection of disperser solvent, volume of extraction solvent, volume of disperser solvent, pH of the aqueous phase, extraction time, salt addition, and centrifugation time were optimized. Validation was conducted according to ISO/IEC 17025:2017 and Commission Implementing Regulation (EU) 2021/808 of 22 March 2021. Validation parameters such as calibration function, matrix effect, limit of detection (LOD), limit of quantification (LOQ), decision limit (CCα), accuracy, and precision were established. Coefficient of determination (R 2) values ranging from .99938 to .99995 were obtained using the matrix calibration curve spiked at 0, 0.25, 1.0, 1.5, and 2.0 times MRL. The LODs and LOQs were calculated using the standard deviation of the response and the slopes of the calibration curves ranged from 0.35 to 26.1 μg/kg and from 1.2 to 87.0 μg/kg, respectively, and were dependent on calibration range. The CCα values ranged from 23 to 1022.0 μg/kg and are also dependent on the MRL concentration levels. The coefficient of variation (CV) values calculated are within the reproducibility range of 16%-30% adapted from the Horwitz Equation CV = 2(1-0.5 log C) and ranged from 1.7% to 16.9%. The developed and validated and the standard QuEChERS method were compared. The IL-DLLME LC-MS/MS method was applied to 32 small stock (18 caprine [goat] and 14 ovine [sheep]) liver samples received from municipal abattoirs at Botswana National Veterinary Laboratory for the analysis of anthelmintic drug residues. The results obtained indicated that the anthelmintic drug residues were all below the detection capability, and therefore, the samples were passed as fit for human consumption.

Increase the Efficiency of Dispersive Liquid-Liquid Microextraction (DLLME) and its Use for the Determination of Lead (II) in Aqueous Solutions

A simple, sensitive, and greener method for green extraction and preconcentration of lead from aqueous media and further assay by UV-Vis spectrophotometer has been developed using 1,5 diphenylthiocarbazone (dithizone). Several factors of dispersive liquid-liquid microextraction (DLLME) including the type and volume of extraction and dispersive solvents, shaking time, the concentration of dithizone as a complexing agent, and pH were optimized. Under optimum selected conditions, the limit of detection (LOD), the limit of quantification (LOQ), the linearity range, the relative standard deviation (RSD), and the Enrichment factor (EF) of the proposed method were obtained at 0.007 ppm, 0.025 ppm, 0.01-0.1 ppm, 4.3% (n = 3) and 40, respectively. This proposed method was successfully applied in the analysis of three synthetic water samples and good spiked recoveries over the range of 96.0–98.5% were obtained.

Fast surface floating organic droplets based dispersive liquid‐liquid microextraction for trace enrichment of multiclass pesticide residues from different fruit juice samples followed by high performance liquid chromatography–diode array detection analysis

AbstractThis study was designed to enable the development of a simple, fast, and environmentally friendly analytical technique utilizing dispersive liquid‐liquid microextraction based on surface floating organic droplets for selective and quantitative enrichment of trace level pesticide contaminants from different fruit juice samples for subsequent detection by high performance liquid chromatography, combined with a diode array detector. The selective extraction was necessitated in order to isolate the seven multiclass pesticide residues frequently occurring in fruit juice samples. The effects of experimental parameters such as pH of sample solution, type and volume of extraction and dispersive solvents, ionic strength and extraction time were optimized. The optimized method was validated using spiked blank sample and satisfactory results for accuracy, with recoveries ranging from 87.23% to 99.45%, with %relative standard deviation between 1.37 and 8.39, precision in terms of %relative standard deviation ≤ 10.78 and linearity at concentration levels from 3 to 1500 ng/ml, which corresponded with correlation coefficients ≥ 0.998. The limits of detection and the limits of quantification were ranged from 1.3×10−2 to 5.3×10−2 and 4.2×10−2 to 1.8×10−1 μg/L, respectively. At the end, the method was successfully applied to analyze real fruit juice samples and target analytes were not detected in real samples.

NADES-assisted sample preparation as a greener alternative for mycotoxins determination in apple-based products

While impressive advancements have been reported in mycotoxin analysis over the last decade, very little has been done to realign the sample treatment to the green sample preparation principles, which are arising more and more relevance in the current analytical chemistry. In this regard, this work proposes the first NADES-assisted sample preparation for the extraction of mycotoxins in food samples.Two protocols using dispersive liquid–liquid microextraction (DLLME) and DLLME with solidification of floating organic drop (DLLME-SFO) assisted with a natural deep eutectic solvent (NADES) were developed and assessed as green sample preparation procedures to extract mycotoxins from apple-based products prior to HPLC-MS/MS analysis. The selected mycotoxins were alternariol, alternariol monomethyl ether, tentoxin and ochratoxin A, which are known to occur in these food matrices. The main variables affecting the extraction efficiency, such as volume of dispersive and extraction solvents, as well as the salting-out effect were evaluated and optimized using a central composite design. In addition, both methodologies were examined and compared in terms of greenness using the newly released metric tool AGREEprep. Due to the use of NADES, the DLLME-SFO method achieved a higher greenness score, and it was selected for further characterization. Matrix-matched calibration curves were used, showing a satisfactory linearity (R2 > 0.99). Limits of detection (LODs) and quantification (LOQs) were below 0.25 and 0.8 µg kg−1, respectively. Recoveries were above 72 % for all the mycotoxins studied in both apple juice and apple puree samples. The validated DLLME-SFO-HPLC-MS/MS method was applied to the analysis of commercial apple juice and puree samples. All the samples analysed were contaminated with at least one mycotoxin with a total concentration ranging from 0.4 to 10.5 µg kg−1.

Dispersive liquid-liquid microextraction/HPLC techniques for determination of oxytetracycline and doxycycline residues in beef samples: method developments and statistical analysis

A rapid, cost-effective and environment-friendly sample pre-treatment method involving dispersive liquid-liquid microextraction (DLLME) and high-performance liquid chromatography (HPLC) was developed and applied for the extraction of oxytetracycline and doxycycline residues in beef samples (liver, kidney and muscle). Several influencing factors associated with the extraction and separation of these antibiotics residues, such as sample size, type and volume of disperser and extraction solvents, centrifugation speed and time, were optimized using Plackett-Burman design and central composite design, while insignificant factors were fixed at values determined using univariate analysis. Figures of merit of the analytical methodology including the limit of detection (LOD), the limit of quantification (LOQ), accuracy (in terms of average recoveries), precision and calibration functions were established according to the European Union commission decision 2002/657/EC. Linearity, in the range of 5–500 µg/kg, was obtained with regression coefficients ranging from 0.9983 – 0.9999. Inter-day repeatability, intra-day precision, LODs and LOQs obtained were 3.81 – 14.90%, 3.80 – 8.70%, 4.21 – 4.69 µg/kg and 14.02 – 15.65 µg/kg respectively. Samples with detectable drug residues have oxytetracycline being the most commonly detected. The developed method was successfully established and the concentration levels of drug residues detected were lower than the European Union set maximum residue level (MRL).

Dispersive Liquid - Liquid Micro extraction Technique Coupled with High Performance Liquid Chromatography Diode Array Detector for the Determination of Sulfonamides in Water Samples

A dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with diode array detection (DLLME-HPLC-DAD) has been developed for the determination of 15 sulfonamides in water samples. The effects of experimental parameters on the performance of the method such as the type and volume of extraction and disperser solvents, pH of the solution, effect of salt, and centrifugation time were evaluated, and optimum conditions were established. Under these optimum conditions, linearity was found in the range of 2 - 1 000 μg L-1 with regression coefficients better than 0.9990. The limit of detection (LOD) and limit of quantification (LOQ) values were in the range of 0.6 - 7.8 μg L-1 and 1.5 - 8.3 µg L-1, respectively. Intra-day and inter-day precision ranged from 1.5 - 9.7% and from 3.1 - 9.9%, respectively. The accuracy of the method were also evaluated in samples from three different sources of water (river water, groundwater, and tap water) were found to range from 70.5 to 103.9% with %RSD values ranging from 0.5 to 9.8%, with the exception of sulfaguanidine in river water and groundwater where the percentage recovery ranged from 54.3 - 84.9% at the two higher concentration levels (100 and 400 µg L-1).Furthermore, the effect of sample matrix on the extraction of target compounds was evaluated using the relative recovery (%RR) of the samples from three different water sources relative to the ultrahigh purity (UHP) water sample spiked with target analytes, and found in the range of 70.3 - 106.1%.The proposed method was successfully applied to wastewater treatment plant samples and Sulfisoxazole (SSO) was detected in the influent samples in the range of 14.8 - 17.8 µg L-1 with corresponding %RSD, (n = 5) value of 1.6% to 1.9%.The results indicated that the proposed method is effective for the extraction and determination of the sulfonamides in water samples.

Dispersive Liquid - Liquid Microextraction for the Determination of Sulfonamide Residues in Egg Samples

A dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-diode array detection was developed for the extraction and determination of 15 sulfonamide residues in the egg matrix. The effects of various parameters such as the type, volume, and composition of extraction solvent for sample treatment procedure, the type and volume of disperser solvent, centrifugation time, salting-out effect and solution pH were studied, and optimum conditions were established. Linearity was found in the range of 5.4 – 1 000 μg kg-1 with regression coefficients ranging from 0.9918 - 0.9987. The limit of detection (LOD) and limit of quantification (LOQ) values of the proposed method were in the range of 4.3 - 8.0 μg kg-1 and 12.9 - 24.0 μg kg-1, respectively. Satisfactory intra-day and inter-day precision results in the range of 6.3 - 17.5% and 4.8 - 16.8%, respectively, were achieved. The accuracy of the method was acceptable with percentage recovery in the range of 73 - 108% and %RSD values in the range of 1.1 - 16.5%. The proposed method was applied in chicken egg samples obtained from supermarkets, and findings confirmed that the method is feasible to be used for extraction and determination sulfonamide residues in egg and related complex biological matrices.

Ionic Liquid-Dispersive Micro-Extraction and Detection by High Performance Liquid Chromatography-Mass Spectrometry for Antifouling Biocides in Water.

A simple analytical method was developed and evaluated for the determination of two antifouling biocides using an ionic liquid-dispersive liquid-liquid micro-extraction (IL-DLLME) and a high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis. Irgarol 1051 and Sea-Nine 211 were extracted from deionized water, lake water, and seawater using IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF6]) and ethyl acetate as the extraction solvent and the dispersion solvent. Several factors were considered, including the type and volume of extraction and dispersive solvent, IL amount, sample pH, salt effect, and cooling temperature. The developed method resulted in a recovery range of 78.7-90.3%, with a relative standard deviation (RSD, n = 3) less than 7.5%. The analytes were enriched greater than 40-fold, and the limits of detection (LOD) for two antifouling biocides were 0.01-0.1 μg L-1. The method was effectively applied for the analysis of real samples of freshwater as well as samples of seawater.

Validation and green profile assessment of a binary solvent liquid phase microextraction method for the determination of chlorbenside and fenobucarb in lake and wastewater samples by GC-MS.

This study reports a liquid phase microextraction method based on binary extraction solvents, which were used to preconcentrate chlorbenside and fenobucarb from aqueous samples for determination by gas chromatography mass spectrometry. Parameters including the type, ratio, and volume of binary solvents, disperser solvent type and volume, and vortex period were optimized systematically to achieve high enrichment for the analytes. The optimum conditions obtained were used to validate the method, and the detection limits calculated for chlorbenside (0.71ng/mL) and fenobucarb (0.33ng/mL) correlated to enrichment factors of 399- and 912-folds, respectively. The optimum method was applied to lake water and wastewater samples in spike recovery experiments, and the results obtained (96-104%) verified the method as accurate and applicable to the aqueous sample matrices. Matrix matching calibration method was used to boost the accuracy of quantifying the two analytes in the wastewater sample, which presented interference effects. Assessment of the method's green profile based on penalty points confirmed the method's compliance with green analytical chemistry.

Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography as an efficient and sensitive technique for determination of nandrolone and testosterone in human urine

AbstractDispersive liquid-liquid microextraction (DLLME) and high performance liquid chromatography – UV detection was presented for extraction and determination of nandrolone and testosterone in human urines. Chloroform at microliter volume level and acetonitrile were used as extraction and dispersive solvents, respectively. The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at µL level. The influence of several variables (e.g. type and volume of disperser and extraction solvents, ionic strength, etc.) on the performance of the sample preparation step was carefully evaluated. Under the optimum conditions, the calibration graphs were linear in the range of 5–500 μg L−1 with detection limit of 2.5 μg L−1 for both of them. The relative standard deviation (R.S.D.s) for five replicate measurements of nandrolone and testosterone were 9.4% and 8.8%, respectively. The relative recoveries of nandrolone and testosterone in urine sample at spiking level of 25.0 μg L−1 are ranged between 86.4% and 98%. DLLME combined with HPLC-UV is a fast, simple and efficient method for the determination of nandrolone and testosterone in human urines.

Quantitative determination of bromochloroacetamide in mice urine by gas chromatography combined with salting-out assisted dispersive liquid-liquid microextraction.

Bromochloroacetamide (BCAcAm) is the main haloacetamide (HAcAm) detected in drinking water in different regions and exhibits strong cytotoxicity and genotoxicity. However, there is no appropriate method for detecting BCAcAm in urine or other biological samples, and thus, the internal exposure level in the population cannot be accurately assessed. In this study, a gas chromatography-electron capture detector (GC-ECD) was combined with salting-out assisted dispersive liquid-liquid microextraction (SA-DLLME) to develop a rapid and robust method for BCAcAm detection in urine of mice continuously exposed to BCAcAm. The factors influencing the pre-treatment procedure, including the type and volume of extraction and disperser solvents, extraction and standing time, and the amount of salt, were evaluated systematically. Under the optimised conditions, the analyte achieved good linearity in the spiked concentration range of 1.00-400.00 μg L-1, and the correlation coefficient was higher than 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.17 μg L-1 and 0.50 μg L-1, respectively. The recoveries ranged from 84.20% to 92.17%. The detection of BCAcAm at three different calibration levels using this method afforded an intra-day precision of 1.95-4.29%, while the inter-day precision range was 5.54-9.82% (n = 6). This method has been successfully applied to monitor the concentration of BCAcAm in mouse urine in toxicity experiments and can provide technical support for assessing human internal exposure levels and health risks in later studies.