Determination of 19 sulfonamides residues in pork samples by combining QuEChERS with dispersive liquid–liquid microextraction followed by UHPLC–MS/MS

A new simple and rapid pretreatment method for simultaneous determination of 19 sulfonamides in pork samples was developed through combining the QuEChERS method with dispersive liquid–liquid microextraction followed by ultra‐high performance liquid chromatography with tandem mass spectrometry. The sample preparation involves extraction/partitioning with QuEChERS method followed by dispersive liquid–liquid microextraction using tetrachloroethane as extractive solvent and the acetonitrile extract as dispersive solvent that obtained by QuEChERS. The enriched tetrachloroethane organic phase by dispersive liquid–liquid microextraction was evaporated, reconstituted with 100 μL acetonitrile/water (1:9 v/v) and injected into an ultra‐high performance liquid chromatography with a mobile phase composed of acetonitrile and 0.1% v/v formic acid under gradient elution and separated using a BHE C₁₈ column. Various parameters affecting the extraction efficiency were investigated. Matrix‐matched calibration curves were established. Good linear relationships were obtained for all analytes in a range of 2.0–100 μg/kg and the limits of detection were 0.04–0.49 μg/kg. Average recoveries at three spiking levels were in the range of 78.3–106.1% with relative standard deviations less than 12.7% (n = 6). The developed method was successfully applied to determine sulfonamide residues in pork samples.     

Liquid–solid disk extraction followed by supercritical fluid elution and gas chromatography of phenols from water

A method combining the techniques of liquid – solid disk extraction (LSDE) and supercritical fluid elution (SFE) has been developed for the phenols regulated by the Clean Water Act. LSDE uses a disk or membrane made of polytetrafluoroethylene (PTFE) fibrils impregnated with small particles, e.g. styrene divinylbenzene (SDB) resin, to extract phenols from water. After disk extraction the retained analytes are eluted from the disk using SFE. SFE is used as an alternative to liquid solvent elution with an organic solvent. Analytes are separated, identified, and quantified using gas chromatography – ion trap detector mass spectrometry (GC-ITDMS). The method is capable of sub parts per billion detection limits, and precision of 5–28% RSD. Evaluation of various disks or membranes, such as C₁₈-silica disks, SDB disks, and ion exchange membranes, has also been performed for the extraction of phenols from water. The results obtained from the in-situ aqueous acetylation of phenols and extraction of their acetates are quantitative. The utilization of LSDE and SFE techniques has proven to be a more effective approach than liquid – liquid extraction in minimizing air pollution and solvent waste.     

Up‐and‐down shaker‐assisted ionic liquid‐based dispersive liquid—liquid microextraction of benzophenone‐type ultraviolet filters

Sun protection is an important part of our lives. UV filters are widely used to absorb solar radiation in sunscreens. However, excess UV filters constitute persistent groups of organic micropollutants present in the environment. An environmentally friendly ionic‐liquid‐based up‐and‐down shaker‐assisted dispersive liquid?liquid microextraction device combined with ultra‐performance liquid chromatography coupled with photodiode‐array detection has been developed to preconcentrate three UV filters (benzophenone, 2‐hydroxy‐4‐methoxybenzophenone, 2,2′‐dihydroxy‐4‐methoxybenzophenone) from field water samples. In this method, the optimal conditions for the proposed extraction method were: 40 μL [C₈MIM][PF₆] as extraction solvent and 200 μL methanol as disperser solvent were used to extract the UV filters. After up‐and‐down shaking for 3 min, the aqueous solution was centrifuged at 5000 rpm speed, then using microtube to collect the settled extraction solvent and using ultra‐performance liquid chromatography for further analysis. Quantification results indicated that the linear range was 2–1000 ng/mL. The LOD of this method was in the range 0.2–1.3 ng/mL with r² ≥ 0.9993. The relative recovery in studies of different types of field water samples was in the range 92–120%, and the RSD was 2.3–7.1%. The proposed method was also applied to the analysis of field samples.     

Hydrophilic solid‐phase extraction of melamine with ampholine‐modified hybrid organic–inorganic silica material

In this work, an ampholine‐functionalized hybrid organic–inorganic silica sorbent was successfully used to extract melamine from a milk formula sample by a hydrophilic interaction solid‐phase extraction protocol. Primary factors affecting the extraction efficiency of the material such as extraction solvent, elution solvent, sample loading volume, and elution volume have been thoroughly optimized. Under the optimized hydrophilic solid‐phase extraction conditions, the recoveries of melamine spiked in milk formula samples ranged from 86.2 to 101.8% with relative standard deviations of 4.1–9.4% (n = 3). The limit of detection (S/N = 3) was 0.32 μg/g. The adsorption capacity toward melamine was 30 μg of melamine per grams of sorbent. Due to its simplicity, rapidity and cost effectiveness, the newly developed hydrophilic solid‐phase extraction method should provide a promising tool for daily monitoring of doped melamine in milk formula.     

Homogeneous liquid–liquid extraction combined with high performance liquid chromatography–fluorescence detection for determination of polycyclic aromatic hydrocarbons in vegetables

In this article, homogeneous liquid–liquid extraction (HOLLE), combined with HPLC-fluorescence detector (HPLC-FLD), has been developed for the extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in vegetables. ACN was used as extraction solvent for the extraction of target analytes from vegetables. When the previous extraction process was over, the ACN extract was transferred to the water-immiscible organic phase, tetrachloroethane, used as extraction solvent in HOLLE procedures. Under the optimum conditions, repeatability was carried out by spiking PAHs at concentration level of 12.5 μg/kg, the RSDs varied between 1.1 and 8.5% (n = 3). The LODs, based on S/N of 3, ranged from 0.025 to 0.25 μg/kg. Relative recoveries of PAHs from cucumber and long crooked squash samples were in the range of 72.4–104.9% and 65.5–119.3%, respectively. Compared with the conventional extraction method, the proposed method has the advantage of being quick, easy to operate, and having low consumption of organic solvent.     

Rapid method for determination of phenylurea herbicides in milk

Summary A method has been developed for the determination of thirteen phenylurea herbicide residues in milk. It involves one-step solvent extraction of the milk with methanol by ultrasonication. The extract is cleaned up on an Amberchrom resin cartridge. Reversed-phase, gradient elution, high-performance liquid chromatography with UV detection at 242 nm is used to analyse the residues. The recovery of thirteen phenylurea pesticides is quantitative, ranging from 71.4% to 97.9% for the individual herbicides investigated at concentrations around 0.05 mg kg^–1 and from 65.1% to 95.6% around 0.005 mg kg^–1. The method is not associated with any of the emulsion problems common to conventional solvent extraction, which considerably reduce the sample clean-up process compared with existing methods.     

Sensitive determination of amide herbicides in environmental water samples by a combination of solid‐phase extraction and dispersive liquid–liquid microextraction prior to GC–MS

In this paper, solid‐phase extraction (SPE) in combination with dispersive liquid–liquid microextraction (DLLME) has been developed as a sample pretreatment method with high enrichment factors for the sensitive determination of amide herbicides in water samples. In SPE–DLLME, amide herbicides were adsorbed quantitatively from a large volume of aqueous samples (100 mL) onto a multiwalled carbon nanotube adsorbent (100 mg). After elution of the target compounds from the adsorbent with acetone, the DLLME technique was performed on the resulting solution. Finally, the analytes in the extraction solvent were determined by gas chromatography–mass spectrometry. Some important extraction parameters, such as flow rate of sample, breakthrough volume, sample pH, type and volume of the elution solvent, as well as salt addition, were studied and optimized in detail. Under optimum conditions, high enrichment factors ranging from 6593 to 7873 were achieved in less than 10 min. There was linearity over the range of 0.01–10 μg/L with relative standard deviations of 2.6–8.7%. The limits of detection ranged from 0.002 to 0.006 μg/L. The proposed method was used for the analysis of water samples, and satisfactory results were achieved.     

Speciation of butyl- and phenyltin compounds in sediments using pressurized liquid extraction and liquid chromatography-inductively coupled plasma mass spectrometry

A liquid chromatographic method with inductively coupled plasma mass spectrometry is proposed for the speciation of butyl- (monobutyltin, dibutyltin, tributyltin) and phenyl- (monophenyltin, diphenyltin, triphenyltin) tin compounds in sediments. After evaluation of different additives in the mobile phase, the use of 0.075% (w/v) of tropolone and 0.1% (v/v) of triethylamine in a mobile phase of methanol-acetic acid-water (72.5:6:21.5) allowed the best chromatographic separation of the six compounds. Pressurized liquid extraction (PLE) with a methanolic mixture of 0.5 M acetic acid and 0.2% (w/v) of tropolone was suitable for the quantitative extraction of butyl- and phenyltin compounds with recovery values ranging from 72 to 102%. This analytical approach was compared to conventional solvent extraction methods making use of acids and/or organic solvent of medium polarity. The main advantages of PLE over conventional solvent extraction are: (i) the possibility to extract quantitatively DPhT and MPhT from sediments, which could not be done by a solvent extraction approach; (ii) to preserve the structural integrity of the organotin compounds; (iii) to reduce the extraction time from several hours in case of solvent extraction techniques to just 30 min. For spiked sediments, limits of detection ranged from 0.7 to 2 ng/g of tin according to the compound. The relative standard deviations were found to be between 8 and 15%. The developed analytical procedure was validated using a reference material and was applied to various environmental samples.     

Miniaturized ternary deep eutectic solvent-based matrix solid-phase dispersion: A green sample preparation method for the determination of chlorophenols in river sediment

New ternary deep eutectic solvents were prepared and applied as efficient green dispersing solvents in miniaturized matrix solid-phase dispersion to extract chlorophenols from river sediments for the first time. High-performance liquid chromatography coupled with a photodiode array detector was used to analyze the target analytes. The significant factors affecting the extraction were optimized as follows: dispersant (100 mg), sample (100 mg), ternary eutectic solvents (150 μl), grinding for 1 min, 450 μl of acetonitrile as the elution solvent, and vortex mixing for 20 s. Under the optimal conditions, the method exhibited excellent linearity (correlation coefficient > 0.9980), low limits of detection between 1.039–2.478 μg/g, and extraction recoveries between 93.9% and 99.2%. Furthermore, the method demonstrated excellent precision in the intra- and inter-day analysis with a relative standard deviation below 6%. When compared to conventional extraction techniques, the miniaturized matrix solid-phase dispersion considerably reduced samples and solvent usag, offering important environmental benefits. The green profile of the method was assessed using the complementary green analytical procedure index tool confirming its eco-friendship. The technique was finally employed to evaluate sediment samples from three distinct locations along the Zuibaiji River, indicating its applicability for monitoring environmental samples.     

化妆品中2种限用呫吨染料的高效液相色谱检测

建立了化妆品种中2种限用呫吨染料酸性黄73和溶剂橙16的高效液相色谱/二极管阵列检测器检测方法。在ODS C18反相色谱柱上,流动相为0.1 mol/L乙酸铵-甲醇-乙腈(体积比为65:17.5:17.5)等度洗脱,检测波长为492 nm,柱温35℃,流速1.0 mL/min。以保留时间定性,外标法定量。在5～500μg/mL范围内,酸性黄73和溶剂橙16的质量浓度与各自相应的峰面积呈现良好的线性关系,仪器检出限均为0.5μg/mL。样品前处理方法采用甲醇作溶剂超声提取,酸性黄73和溶剂橙16的加标回收率分别在91.2%～106.2%和93.2%～101.5%范围内。     

Dispersive liquid–liquid microextraction using a surfactant as disperser agent

A novel and efficient surfactant-assisted dispersive liquid–liquid microextraction combined with high-performance liquid chromatography–photodiode array detection was developed for the determination of phenylurea herbicides in water samples. Based on this procedure, which is a dispersive-solvent-free technique, the extractant is dispersed in the aqueous sample using methyltrialkylammonium chloride. Compared with the conventional dispersive liquid–liquid microextraction, the new extraction method has many advantages such as higher extraction efficiency, low cost, reduced environmental hazards, and consumption of less extracting solvent. A few microliters of chloroform containing an appropriate amount of methyltrialkylammonium chloride (mixture of C8–C10) was used to extract the analytes from water samples. The main parameters relevant to the extraction process (namely, type of surfactant, selection of extractant solvent, extractant volume, surfactant concentration, ionic strength, and extraction time) were investigated. The performed analytical procedure showed limits of detection ranging from 2.3 to 18 ng/L, and precision ranges from 0.6% to 2.0% (as intra-day relative standard deviation, RSD) and from 1.3% to 8.3% (as inter-day RSD) depending on the analyte. The method showed good linearity between 0.04 and 40 μg/L with squared correlation coefficients better than 0.9920. This newly established approach was successfully applied to spiked real water samples.     

Extraction and determination of linear alkylbenzenesulfonate detergents from the aquatic environment using a membrane disk and gas chromatography

Levels of linear alkylbenzenesulfonate (LAS) detergents have been measured in Anzali lagoon water sampled at fourteen stations. All samples were extracted with octadecyl-bonded silica membrane disks. Extraction efficiency, maximum capacity, and the effect of the solvent used to extract the LAS from the membrane disks were evaluated. Extraction efficiencies > 95% were obtained by elution of the disks with minimal amounts of solvent. It was demonstrated that membrane disk extraction introduced less error into analytical results than liquid – liquid extraction. Quantitative determination of total LAS levels and measurement of the distribution of LAS homologs with C₁₀? C₁₃ alkyl chains were performed by high resolution gas chromatography with flame ionization detection after derivatization of the detergents with sulfonyl chloride. The total level of LAS ranged from 0.01 to 0.89 ppm.     

Effects of different extraction methods and conditions on the phenolic composition of mate tea extracts

A simple and rapid HPLC method for determination of chlorogenic acid (5-O-caffeoylquinic acid) in mate tea extracts was developed and validated. The chromatography used isocratic elution with a mobile phase of aqueous 1.5% acetic acid-methanol (85:15, v/v). The flow rate was 0.8 mL/min and detection by UV at 325 nm. The method showed good selectivity, accuracy, repeatability and robustness, with detection limit of 0.26 mg/L and recovery of 97.76%. The developed method was applied for the determination of chlorogenic acid in mate tea extracts obtained by ethanol extraction and liquid carbon dioxide extraction with ethanol as co-solvent. Different ethanol concentrations were used (40, 50 and 60%, v/v) and liquid CO? extraction was performed at different pressures (50 and 100 bar) and constant temperature (27 ± 1 °C). Significant influence of extraction methods, conditions and solvent polarity on chlorogenic acid content, antioxidant activity and total phenolic and flavonoid content of mate tea extracts was established. The most efficient extraction solvent was liquid CO? with aqueous ethanol (40%) as co-solvent using an extraction pressure of 100 bar.     

Ultrapreconcentration and determination of organophosphorus pesticides in water by solid‐phase extraction combined with dispersive liquid–liquid microextraction and high‐performance liquid chromatography

Solid‐phase extraction coupled with dispersive liquid–liquid microextraction was developed as an ultra‐preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion‐methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid‐phase extraction coupled with dispersive liquid–liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid‐phase extraction coupled with dispersive liquid–liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9–6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.     

LC–MS–MS Determination of Stabilizers and Explosives Residues in Hand-Swabs

The contribution of explosive trace detection in samples from the hands of suspects has been fundamental in several forensic cases involving terrorists. This paper describes a method for the rapid extraction and unequivocal confirmation of some high potential explosives (trinitrotoluene, cyclotrimethylenetrinitramine, pentaerythritol tetranitrate, nitroglycerin) and two stabilizer (diphenylamine and ethylcentralite) residues in hand-swabs using liquid chromatography–tandem mass spectrometry. The extraction procedure of the analytes from the swabs is realized by solvent elution and the extracts are directly analyzed. Recoveries from spiked swabs range from 78 to 96%; the limits of quantification are between 0.04 and 1.8 ng injected and the inter-day method precision is less than 15%. The developed procedure was applied to the detection of explosives traces in samples after handling tests.     

Multiwalled‐carbon‐nanotubes‐based matrix solid‐phase dispersion extraction coupled with high‐performance liquid chromatography for the determination of honokiol and magnolol in Magnoliae Cortex

In this paper, multiwalled‐carbon‐nanotube‐based matrix solid‐phase dispersion coupled to HPLC with diode array detection was used to extract and determine honokiol and magnolol from Magnoliae Cortex. The extraction efficiency of the multiwalled‐carbon‐nanotube‐based matrix solid‐phase dispersion was studied and optimized as a function of the amount of dispersing sorbent, volume of elution solvent, and flow rate of elution solvent, with the aid of response surface methodology. An amount of 0.06 g of carboxyl‐modified multiwalled carbon nanotubes and 1.5 mL of methanol at a flow rate of 1.1 mL/min were selected. The method obtained good linearity (r² > 0.9992) and precision (RSD < 4.7%) for honokiol and magnolol, with limits of detection of 0.045 and 0.087 μg/mL, respectively. The recoveries obtained from analyzing in triplicate spiked samples were determined to be from 90.23 to 101.10% and the RSDs from 3.5 to 4.8%. The proposed method that required less samples and reagents was simpler and faster than Soxhlet and maceration extraction methods. The optimized method was applied for analyzing five real samples collected from different cultivated areas.     

高效液相色谱-离子阱质谱法快速筛查改善睡眠类保健食品中非法添加的24种镇静催眠药

建立了高效液相色谱-离子阱质谱(HPLC-IT MS)同时测定改善睡眠类保健食品中非法添加的24种镇静催眠药的快速筛查方法。样品经甲醇超声提取20 min,经0.45 μm滤膜过滤后进行HPLC-IT MS分析检测。采用Phenomenex Luna C18色谱柱分离,流动相A为0.05%(v/v)甲酸水溶液,流动相B为甲醇-乙腈(15:25, v/v)溶液,等度洗脱;采用电喷雾离子(ESI)源及正、负离子切换模式,扫描MS¹~MS³三级质谱,利用24种药物的MS/MS(MS²)和MS/MS/MS(MS³)质谱对样品进行定性筛查。24种镇静催眠药品在一定线性范围内线性关系良好,相关系数(r²)均大于0.999,检出限在4.0~446.6 μg/L之间,3个添加水平的回收率为88.6%~110.3%,相对标准偏差(RSD)在0.8%~9.8%之间。27批样品经筛查发现有18批样品检出褪黑素。该方法快速、灵敏、处理方法简单,可用于保健食品中非法添加镇静催眠类药品的快速筛查。     

Active single-drop microextraction for the determination of gaseous diisocyanates

Heterocyclic amines (HAs) were analysed in meat extract samples using a new method based on pressurised liquid extraction (PLE) and liquid chromatography-tandem mass spectrometry. This method combines the use of a pressurised fluid with a triple quadrupole MS/MS system, resulting in benefits from both systems: high extraction efficiency and sensitivity. The effects of solvent type and PLE operational parameters, such as temperature and extraction time, were studied to obtain maximum recovery of the analytes with minimum contamination. HA extraction was best achieved using dichloromethane/acetone (50/50, v/v) at 80 degrees C for 10 min. Recoveries ranged from 45% to 79% with good quality parameters: limit of detection values between 0.02 and 1 ng g(-1), linearity (r(2)>0.997), and run-to-run and day-to-day precisions with relative standard deviations lower than 13% achieved at both low (0.20 microg g(-1)) and medium (1.0 microg g(-1)) concentrations. This method reduces sample manipulation and total extraction time by nearly four-fold compared to conventional solid phase extraction. The optimised method was validated using laboratory reference material based on a meat extract, and was successfully applied to HA analysis in several cooked beef samples.     

Extraction of Anthraquinones from Rhubarb by a Molecularly Imprinted–Matrix Solid-Phase Dispersion Method with HPLC Detection

A simple method based on matrix solid-phase dispersion for selective extraction of anthraquinones from rhubarb samples was developed using a molecularly imprinted polymer as sorbent. The molecularly imprinted polymer was prepared using emodin as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking agent. The polymer was characterized by scanning electron microscopy and Fourier-transform infrared spectrometry. Isothermal adsorption and dynamic adsorption experiments were performed. The best extraction conditions for anthraquinones were obtained at a ratio of molecularly imprinted polymer to sample of 1:1, a dispersion time of 5 minutes, with 5% aqueous methanol as the washing solvent, and an elution solvent of methanol-acetic acid (99:1, v/v). Once the matrix solid-phase dispersion process was optimized, the extract was reacted with 8% hydrochloric acid for hydrolysis. The anthraquinones extracted from rhubarb were determined by liquid chromatography. The detection limits of chrysophanol, emodin, physcion, and aloe-emodin were 0.23, 0.24, 0.28, and 0.27 µg mL^?1, respectively. The proposed method was compared with the method in Chinese pharmacopoeia, and the results show that the extraction yield of anthraquinones obtained by molecularly imprinted polymer–matrix solid-phase dispersion method was higher. Moreover, the proposed method is faster and simpler and can achieve extraction and purification in the same system.     

Accelerated solvent extraction combined with dispersive liquid–liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples

A method combining accelerated solvent extraction with dispersive liquid–liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m‐cresol, 2,4‐dichlorophenol, and 2,4,6‐trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid–liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid–liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1–3080 ng/g), low limits of detection (0.06–1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9–110%. These findings indicate that accelerated solvent extraction with dispersive liquid–liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.