Ion-Pair-Based Air-Assisted Liquid–Liquid Microextraction for the Extraction and Preconcentration of Phthalic Acids from Aqueous Samples

In the present study, a rapid, simple, and highly efficient sample preparation method based on ion-pair air-assisted liquid–liquid microextraction using a low-density extraction solvent followed by high performance liquid chromatography–diode array detection has been developed for the extraction, preconcentration, and determination of three phthalic acids (phthalic acid, iso-phthalic acid, and terephthalic acid) in aqueous samples. In this method, a mixture of tri-butyl amine (as an ion-pair reagent) and toluene (as an extraction solvent) is transferred into an aqueous sample solution. Fine organic solvent droplets are formed by aspirating and dispersing of the mixture via syringe needle. After that, the formed ion-pairs are extracted into toluene, and after centrifuging, the obtained collected phase is transferred into a microtube and is evaporated to dryness under a stream of nitrogen at room temperature. The residue is re-dissolved in mobile phase and injected into the separation system for analysis. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.09–0.24 and 0.29–0.78 ng mL^?1, respectively. Extraction recoveries and enrichment factors were from 88 to 98 % and 443 to 491, respectively. Relative standard deviations for the extraction of 5 ng mL^?1 of each analyte were less than 8.4 % for intra-day (n?=?6) and inter-days (n?=?5) precisions. Finally, different aqueous samples were successfully analyzed using the proposed method, and the target analytes were determined in some of them at ng mL^?1 level.     

Graphene-Based Preconcentration System Prior to Energy Dispersive X-Ray Fluorescence Spectrometric Determination of Co,Ni, and Cu Ions in Wine Samples

A combination of dispersive micro solid-phase extraction (DMSPE), based on graphene as a solid sorbent, with energy dispersive X-ray fluorescence spectrometry (EDXRF) is proposed for preconcentration and determination of Co(II), Ni(II), and Cu(II) ions in wine samples. In the developed procedure, cupferron complexes of metal ions are adsorbed on graphene dispersed in aqueous samples. After the adsorption process, aqueous samples are passed through a membrane filter with the use of filtration assembly, and then loaded filters are directly measured using EDXRF. In order to obtain high recovery of the metal ions, various analytical parameters influencing sorption were optimized, such as pH, amount of graphene, Triton X-100 and cupferron, sample volume, and sorption time. Under optimal conditions, the calibration plots cover the 2 to 100 ng mL^?1 range for Co(II) and Ni(II), and 2 to 150 ng mL^?1 for Cu(II). The detection limits of 0.08, 0.08, and 0.07 ng mL^?1 for Co(II), Ni(II), and Cu(II) were obtained using 50 mL sample volume and 200 μg of graphene. The precision (at a 20 ng mL^?1 level for n?=?10) is lower than 3.5 %. The proposed method was successfully applied to determination of Co, Ni, and Cu in wine samples.     

A Miniaturized Preconcentration Method Based on Dispersive Liquid–Liquid Microextraction for the Spectrophotometric Determination of Aziridine in Food Simulants

In this work a simple, rapid and sensitive method using dispersive liquid–liquid microextraction (DLLME) combined with UV–Vis spectrophotometry has been developed for the preconcentration and determination of trace amounts of aziridine in food simulants. The method is based on derivatization of aziridine with Folin's reagent (1,2-naphthoquione-4-sulphonic acid) and extraction of color product using DLLME technique. Some important parameters, such as reaction conditions, and type and volume of extraction solvent and disperser solvent were studied and optimized. Under optimum conditions, a linear calibration curve in the range of 2.0–350 ng mL^?1 of aziridine was obtained. Detection limit based on 3S_b was 1.0 ng mL^?1, and the relative standard deviation for 50 ng mL^?1 of aziridine was 2.49c (n?=?7). The proposed method was applied for the determination of aziridine in food simulants.     

Vortex-Assisted Liquid–Liquid Microextraction Combined with HPLC for the Simultaneous Determination of Five Phthalate Esters in Liquor Samples

A vortex-assisted liquid–liquid microextraction (VALLME) method using hexanoic acid as extractant followed by high-performance liquid chromatography–diode array detection was developed for the extraction and determination of five phthalate esters (PAEs) including bis-methylglycol ester (DMEP), benzyl butyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-n-butyl phthalate (DBP), and di-n-octyl phthalate (DNOP) from liquor samples. In this method, hexanoic acid was employed as extraction solvent, because its density is lower than water. And vortex mixing was utilized as a mild emulsification procedure to reduce emulsification time and improve the effect of extraction. Under the studied conditions, five phthalate esters were successfully separated within 20 min and the limits of detection were 2.3 ng mL^?1 for DMEP, 1.1 ng mL^?1 for BBP, 1.9 ng mL^?1 for DCHP, 1.2 ng mL^?1 for DBP, and 1.5 ng mL^?1 for DNOP, respectively. Recoveries of the PAEs spiked into liquor samples were ranged from 89 to 93 %. The precisions of the proposed method were varied from 1.6 to 2.6 % (RSD). The VALLME method has been proved to have the potential to be applied to the preconcentration of the target analytes. Moreover, the method is simple, high sensitivity, consumes much less solvent than traditional methods and environmental friendly.     

Simultaneous determination of sorbic and benzoic acids in milk products using an optimised microextraction technique followed by gas chromatography

A rapid and reliable method for direct determination of sorbic and benzoic acids in milk products was developed by dispersive liquid–liquid microextraction (DLLME) and gas chromatography with flame ionisation detector (GC-FID). A response surface methodology (RSM) based on a central composite design (CCD) was applied for optimisation of the main variables, such as volume of extraction and dispersive solvents, pH and salt effect. The primary extraction of sorbic and benzoic acids were performed in 8 mL NaOH (0.1 M) in a closed-vessel system. Carrez solutions (potassium hexaferrocyanide and zinc acetate) were used for protein sedimentation. The best simultaneous extraction efficiency was identified using acetone and 1-octanal as dispersive and extraction solvents, respectively. For DLLME, central composite design resulted in the optimised values of microextraction parameters as follows: 475 µL of dispersive and 60 µL of extraction solvents, 2 g NaCl at pH 2.5. Under optimum conditions, the calibration curve was linear over the range 0.1–50 μg mL^?1 and the square of correlation coefficient (R²) was 0.9992 for sorbic acid and 0.9994 for benzoic acid. Relative standard deviation (RSD %) was 6.1% and 3.1% (n = 5) for sorbic and benzoic acids, respectively. Limits of detection were 150 ng g^?1 for sorbic acid and 140 ng g^?1 for benzoic acid and recoveries were 88% and 103.7% respectively. Good reproducibility (RSD %), short extraction time and no matrix interference were advantages of the proposed method which was successfully applied to the determination of sorbic and benzoic acids in milk products.     

Determination of Cobalt in Food and Water Samples by Ultrasound-assisted Surfactant-enhanced Emulsification Microextraction and Graphite Furnace Atomic Absorption Spectrometry

A novel method based on ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) has been developed for the preconcentration of cobalt prior to its determination by graphite furnace atomic absorption spectrometry. In the UASEME technique, chloroform was used as the extraction solvent, sodium dodecyl sulfate was adopted as emulsifier, and ultrasound was applied to assist emulsification. There is no need of using organic dispersive solvent which is typically required in conventional dispersive liquid–liquid microextraction method. Several parameters that affect the extraction efficiency, such as the kind and volume of the extraction solvent, the type and concentration of the surfactant, pH of sample solution, concentration of the chelating agent, and extraction time and temperature were investigated and optimized. Under the optimal conditions, the linearity of calibration curve was in the range of 0.1–5 ng mL^?1 with a correlation coefficient (R ²) of 0.9992. An enrichment factor of 58 was achieved with a sample volume of 5.0 mL. The detection limit of this method for Co was 15.6 ng L^?1, and the relative standard deviation (RSD) was 4.3 % at 1.0 ng mL^?1 concentration level of Co. The accuracy of the developed method was evaluated by analysis of the certified reference materials GBW07605 tea leaf and GBW10015 spinach. The method was successfully applied to determine trace cobalt in food and water samples with satisfactory results.     

One-Step Synthesis of Zirconia and Magnetite Nanocomposite Immobilized Chitosan for Micro-Solid-Phase Extraction of Organophosphorous Pesticides from Juice and Water Samples Prior to Gas Chromatography/Mass Spectroscopy

In this research, a magnetic sorbent was prepared by immobilizing zirconia and magnetite (Fe₃O₄) nanoparticles in chitosan, which is characterized and used as an effective nanosorbent in magnetic dispersive micro-solid-phase extraction (MDMSPE) of organophosphorous pesticides (OPPs) from juice and water samples prior to gas chromatography-mass detection (GC-MS). The properties and morphology of synthesized sorbent were characterized by scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), and differential scanning calorimetric (DSC) analysis. The main experimental parameters including pH level, extraction time, sorbent mass, salt concentration, and desorption conditions were investigated and optimized to maximize extraction efficiency. Under optimized conditions, the calibration curves were obtained in the concentration range of 0.1–500 ng mL^?1 with correlation coefficients between 0.9993 and 0.9999. The limits of detection (signal-to-noise ratio (S/N) = 3) and limits of quantification (S/N = 10) of the method ranged from 0.031 to 0.034 ng mL^?1 and 0.105–0.112 ng mL^?1, respectively. The intra-day and inter-day RSDs were 2.2–5.7 and 2.5–7.5%, respectively. The method was successfully applied to the analysis of OPPs in fruit juices (apple, peach, and cherry) and water (mineral, tap, and river) real samples, with recoveries in the range of 86.0–106.0% for the spiked juice and water samples. The results showed that with combination of high selectivity of zirconia and magnetic property of magnetite as well as immobilizing ability of chitosan, the fabricated sorbent exhibited exceptional extraction ability toward the OPPs.     

Novel Binary Solvents-Dispersive Liquid—Liquid Microextraction (BS-DLLME) Method for Determination of Patulin in Apple Juice Using High-Performance Liquid Chromatography

A simple and rapid binary solvents-based dispersive liquid–liquid microextraction (BS-DLLME) method has been developed for determination of patulin (PAT) in apple juice followed by high-performance liquid chromatography. This method involves the use of an appropriate mixture of miscible binary extraction solvents and disperser solvent to form fine droplets of extractant in a sample solution. Parameters affecting extraction efficiency such as the type and volume of high-density extraction solvent, the volume of ethyl acetate, the kind and volume of disperser solvent, and salt addition were investigated and optimized. The detection and quantification limits were 2.0 and 10.0 μg L^?1, respectively. The relative standard deviation for five measurements of 25 μg L^?1 of PAT was 3.8 %. The relative recoveries of PAT from apple juice samples at spiking levels of 25, 50, and 75 ng mL^?1 were in the range of 91.3–95.2 %.     

Establishment of an Aqueous PEG 200-Based Deep Eutectic Solvent Extraction and Enrichment Method for Pumpkin (<Emphasis Type="Italic">Cucurbita moschata</Emphasis>) Seed Protein

A novel approach for ultrasound–microwave synergistic extraction (UMSE) of pumpkin seed protein was developed using aqueous poly (ethylene glycol) (PEG 200)-based deep eutectic solvent (DES) as a green extraction medium. Key factors controlling the extraction and optimal operating conditions were optimized by combining the one variable at a time and response surface methodology. Results showed that the PEG 200 as a hydrogen bond donor combined with choline chloride as a typical hydrogen bond acceptor had a highest extraction efficiency among different solvents. The optimal extraction parameters were optimized as follows: PEG 200-based DES concentration, 28% w/w; solid to liquid ratio, 28 g mL^?1; microwave power, 140 W; and extraction temperature, 43 °C. Under the optimal parameters, the actual extraction yield was 93.95 ± 0.23% (n = 3). The precipitation rate of pumpkin seed protein was 97.97% with a precipitation time of only 4 min by using an isoelectric point-ethanol-PEG 200 DES ternary co-precipitation method. Overall, this integrated method of PEG 200-based DES and UMSE exhibits a powerful tool for the rapid and efficient extraction of pumpkin seed protein.     

Optimization of the QuEChERS Method for Determination of Pesticide Residues in Chicken Liver Samples by Gas Chromatography-Mass Spectrometry

The goal of this research was to evaluate the application of Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method for the determination of organochlorine, organophosphate, and carbamate pesticides in fatty animal matrices such as liver of chicken obtained from National Research Institute of Animal Production in Balice (Poland). Pesticides extraction effectiveness was evaluated at two different spiking levels (0.010 and 0.020 mg kg^?1) and efficiency of the dispersive solid-phase extraction (d-SPE) clean-up step was evaluated by comparison adding different d-SPE sorbent combinations (PSA?+?GCB, PSA?+?C₁₈, PSA?+?SAX, and PSA?+?NH₂). The analysis of pesticide residues was performed by gas chromatography ion trap mass spectrometry (GC/IT-MS). The linear relation was observed from 0 to 400 ng mL^?1 and the determination coefficient R ²?>?0.997 in all instances for all target analytes. Better recoveries were obtained in samples at 0.020 mg kg^?1 spiking level. The recoveries were in the range 70–120 %, with relative standard deviation (RSD) values lower than 15 % at 0.020 mg kg^?1 spiking level for most pesticides. Similar recovery ratios were obtained with the four different combinations of sorbents tested in the clean-up step, with better precision when the (PSA?+?SAX) combination was tested. Limits of detection (LODs) ranged from 0.001 to 0.005 mg kg^?1 and limits of quantification (LOQs) ranged from 0.003 to 0.015 mg kg^?1. The proposed method was successfully applied analyzing pesticide residues in real chicken liver samples; detectable pesticide residues were observed, but in all of the cases, the contamination level was lower than the default maximum residue levels (MRLs) set by European Union (EU), Regulation (EC) N 396/2005.     

Application and Optimization of Microwave-Assisted Extraction and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography for the Determination of Oleuropein and Hydroxytyrosol in Olive Pomace

In the present study, a new method based on microwave-assisted extraction and dispersive liquid–liquid microextraction (MAE–DLLME) followed by high-performance liquid chromatography (HPLC) was proposed for the separation and determination of oleuropein (Ole) and hydroxytyrosol (HyT) from olive pomace samples. The effective factors in the MAE–DLLME process such as microwave power, extraction time, the type and volume of extraction, and dispersive solvents were studied and optimized with the aid of response surface methodology (RSM) based on a central composite design (CCD) to obtain the best condition for Ole and HyT extraction. At the optimized conditions, parameter values were 220 W microwave power, 12 min extraction time, 60 μL extracting solvent, and 500 μL dispersive solvent. The calibration graphs of the proposed method were linear in the range of 10–500,000 μg L^?1, with the coefficient of determination (R²) higher than 0.99 for Ole and HyT. Repeatability of the method, described as the relative standard deviation (RSD), was 4.12–5.63% (n?=?6). The limits of detection were 35 and 20 μg L^?1 for Ole and HyT, respectively. The recoveries of these compounds in the spiked olive pomace sample were from 93 to 98%. The proposed method, MAE–DLLME–HPLC–UV, was an accurate, rapid, and reliable method when compared with previous methods.     

Hollow Fiber Liquid Phase Microextraction Method Combined with High-Performance Liquid Chromatography for Simultaneous Separation and Determination of Ultra-Trace Amounts of Naproxen and Nabumetone in Cow Milk,Water, and Biological Samples

A simple and highly sensitive method based on hollow fiber liquid phase microextraction combined with high-performance liquid chromatography and fluorescence detection has been developed for simultaneous separation, preconcentration, and determination of naproxen and nabumetone from water, wastewater, milk, and biological samples. Parameters affecting the microextraction efficiency were evaluated and optimized. Under optimum conditions (extractant (14 μL of 1-undecanol), sample pH (3.0), extraction time (20 min), stirring rate (600 rpm), temperature (45 °C), potassium chloride concentration (4.0 %) and sample volume (9 mL)), the limits of detection based on (S/N?=?3) were 1.3 ng L^?1 for naproxen and 2.9 ng L^?1 for nabumetone. The intra- and inter-assay relative standard deviations for naproxen and nabumetone were in the ranges of 3.2–6.1 % and 6.5–9.5 %, respectively. The calibration curves were linear in concentration ranges of 4.0–300.0 ng L^?1 and 9.0–300.0 ng L^?1 for naproxen and nabumetone, respectively, with good coefficient of determination (r ²?>?0.999). The method was successfully applied to the determination of naproxen and nabumetone in cow milk, water, wastewater, human plasma, and urine samples.     

Simultaneous Determination of Seven Polycyclic Aromatic Hydrocarbons in Coffee Samples Using Effective Microwave-Assisted Extraction and Microextraction Method Followed by Gas Chromatography-Mass Spectrometry and Method Optimization Using Central Composite Design

In this research, for the first attempt, we successfully determined seven polycyclic aromatic hydrocarbons (PAHs) in various coffee samples using microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) coupled with gas chromatography-mass spectrometry (GC-MS). The effects of most important variables in microextraction step were investigated and optimized using response surface methodology (RSM) based on central composite design. The calibration curves were linear in the range of 1–200 ng g^?1, with a correlation coefficient (R ²) higher than 0.989. Limits of detection were obtained between 0.1 and 0.3 ng g^?1. The relative standard deviations (RSD%) for seven repeated analysis were less than 8% for all PAH compounds at a concentration of 10 ng g^?1. Relative recoveries were obtained 88.1–101.3%. The satisfactory results obtained by the proposed method and the comparison of these results with previous methods demonstrated that the MAE-DLLME-GC-MS is an accurate, rapid, and reliable sample-pretreatment method with low consumption of the organic solvent.     

Determination of Trace Amounts of Cd(II), Cu(II), and Ni(II) in Food Samples Using a Novel Functionalized Magnetic Nanosorbent

This work describes a novel sorbent based on functionalization of magnetic nanoparticles by 2-aminobenzothiazole and its application in the extraction and preconcentration of trace amount of Cd(II), Cu(II), and Ni(II) ions. This nanosorbent was characterized by Fourier transfer infrared spectroscopy, thermal analysis, X-ray powder diffraction, elemental analysis, and scanning electron microscopy. The effects of various factors such as pH value, sorption time, sorbent dosage, type, volume, and concentration of the eluent as well as the elution time were investigated. Following the sorption and the elution of target analytes, the Cd(II), Cu(II), and Ni(II) ions were determined by flame atomic absorption spectrometry. Under the optimal conditions, the limits of detection (LODs) were 0.03, 0.009, and 0.1 μg L^?1 for Cd(II), Cu(II), and Ni(II), respectively. Linearity was within the range of 0.1–75 ng mL^?1 for Cd(II), 0.03–50 ng mL^?1 for Cu(II), and 0.5–100 ng mL^?1 for Ni(II) in the initial solution with r ² values greater than 0.9978. The relative standard deviations of the method were less than 8.4 %. The preconcentration factor of the method was 277. The sorption capacity of this new sorbent was 65, 78, and 49 mg g^?1 for Cd(II), Cu(II), and Ni(II), respectively. The proposed method was validated using two certified reference materials (LGC 6010 hard drinking water and NIST SRM 1515 apple leaves) in order to exhibit its applicability. Ultimately, this method was applied to the rapid extraction of the trace quantities of Cd(II), Cu(II), and Ni(II) ions in different food samples, and satisfactory results were obtained.     

Separation/Analysis Safranine T in Food Samples Using Surfactant/Ionic Liquid Aqueous Two-Phase Systems

Sodium dodecyl sulfate (SDS)/room temperature ionic liquids (RTILs) 1-hexyl-3-methylimidazolium bromide aqueous two-phase systems (ATPSs) are presented as separation/enrichment coupled with ultraviolet spectrometry for separation/analysis safranine T in food samples. The main factors affecting the ATPSs, such as amount of SDS, RTILs, pH, and time, have been investigated in detail. Under the optimal conditions, the linear calibration curves for safranine T was obtained over the concentration ranges of 0.05–4.0 μg mL^?1 with the correlation coefficient (R) 0.9984 and the detection limits of safranine T was 3.8 ng mL^?1. The mechanism of ATPS phase separation for safranine T has been discussed. The method was successfully applied to the determination of safranine T in food samples.     

Graphene Reinforced Hollow Fiber Liquid-Phase Microextraction Combined with HPLC for the Determination of Bisphenol A and 4-Tert-Butylphenol in Bottled Juice

A new analytical method by graphene-reinforced hollow fiber liquid-phase microextraction combined with high-performance liquid chromatography fluorescence detection was developed for the determination of bisphenol A and 4-tert-butylphenol in bottled juices. Several important experimental parameters were studied to get optimal extraction conditions for the analytes. Under the optimized conditions, the method showed a good performance having a linear response in the range from 0.05 to 10.0 ng mL^?1 with the correlation coefficients (r) of 0.9965–0.9994 and limits of detection of 0.01 ng mL^?1. The relative standard deviations were in the range from 6.4 to 7.2 % at the spiked concentration of 1.0 ng mL^?1. The method combines the high-adsorption capacity of graphene and the excellent clean-up performance of hollow fiber liquid-phase microextraction and has been successfully applied to the analysis of the analytes in bottled juice samples.     

Calixarene-Based Miniaturized Solid-Phase Extraction of Trace Triazine Herbicides from the Honey and Milk Samples

A fast, simple, and cost-effective miniaturized solid-phase extraction method using calixarenes as adsorbent was developed for the micro-extraction of cyanazine, simazine, atrazine, and propazine from complex samples. The ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was employed for the structural identification of target compounds. The parameters affecting the performance of extraction, such as the type of sorbents, the amount of the sorbent, desorption solvents, breakthrough volume, and adsorption capacity, were optimized. Under optimal conditions, the linear range was 6–600 ng mL^?1 with the coefficients of determination from 0.9943 to 0.9998. The limits of detection and quantification for the four triazines were 0.01–0.04 and 0.04–0.15 ng mL^?1, respectively. The proposed method was successfully used to determine triazine herbicides in the honey and milk samples.     

Determination of Menbutone in Bovine Milk and Meat Using Micellar Liquid Chromatography: Application to Injectable Dosage Forms

A simple, sensitive, and rapid method was developed for the routine identification and quantification of menbutone in different matrices by micellar liquid chromatography. Separation was performed in less than 4 min using a C₁₈ column with UV detection at 234 nm. A micellar solution composed of 0.12 M sodium dodecyl sulfate, 8 % n-butanol, and 0.3 % triethylamine in 0.02 M phosphoric acid at pH 6.0 was used as the mobile phase. The method was fully validated in accordance with International Conference on Harmonization (ICH) guidelines. The limits of detection and quantitation were 0.95 and 2.86 ng mL^?1, respectively. The method showed good repeatability, linearity, and sensitivity according to the evaluation of the validation parameters. The micellar method was successfully applied for the analysis of menbutone in its commercial injections with a mean % recovery value of 99.73?±?1.634 % and in spiked bovine milk and meat samples with a mean % recovery values in the range of 98.00–100.60 %. High extraction efficiency was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step. Hence, this method can be considered as an interesting example for green chemistry.     

Determination of Eugenol in Aquatic Products by Dispersive Solid-Phase Extraction and Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel procedure, dispersive solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), was developed for the determination of eugenol in aquatic products (shrimp, crab, and carp). Aquatic products were extracted with acetonitrile and primarily purified by dispersive solid-phase extraction with graphitized carbon black as absorbent. The pretreated acetonitrile extract was detected by UHPLC-MS/MS. UHPLC was carried out on Dikma Endeavorsil C₁₈ (30 mm × 2.1 mm, 1.8 μm) column eluted by methanol and water (80:20 v/v) at a rate of 0.30 mL min^?1. Tandem mass spectrometry was performed by electrospray ionization in negative ion mode to identify and quantify eugenol during multiple reaction monitoring. Under optimized analytical conditions, the matrix-matched spiked calibration sample demonstrates good linearity between 5.0 and 500.0 μg kg^?1 with a linear regression coefficient of 0.9996. The average recovery of eugenol from aquatic products is 95.3–103.4% at spiked levels between 5 and 50 μg kg^?1 with a relative standard deviation (n = 6) less than 5.4%. The limits of detection and quantification for eugenol were calculated to be 1.47 and 4.91 μg kg^?1, respectively. In comparison with those reported, the proposed method has advantages in low detection limit, high recovery, and short analysis time, meeting the requirements for the determination of trace eugenol residue in aquatic products.     

Sensitive Determination of Bromate in Water Samples by Capillary Electrophoresis Coupled with Electromembrane Extraction

Electromembrane extraction (EME) as a novel sample preparation technique was firstly applied for the purification and enrichment of bromate (BrO₃ ^?) in drinking water prior to capillary zone electrophoresis with capacitively coupled contactless conductivity detection (CZE-C⁴D). BrO₃ ^?, as the primary disinfection by-product of ozonation, could be well separated with the major inorganic anions coexisting in water samples using a 300 mmol L^?1 acetic acid solution as the running buffer. Under the optimum conditions, the calibration curve showed good linearity (r ²?=?0.996), and the limit of detection was down to 0.12 ng mL^?1 with the enrichment factor at 267. The relative standard deviation (RSD) values for peak area and migration time at a spiked concentration of 10 ng mL^?1 of bromate were below 8.8 and 2.5 %, respectively. This proposed EME-CZE-C⁴D method has been successfully applied to analyze bottled drinking water and tap water samples with recoveries in the range of 85~98 %, providing an alternative to the determination of bromate in drinking water.