Effects of Protein on the Detection of Chlorobenzenes in Fish and Their Elimination by Modified QuEChERS Method

Molecular fluorescence spectrometry, resonance Rayleigh scattering and gas chromatography-mass spectroscopy（GC-MS） were used to study the effect of pure fish serum albumin（FSA） as the model protein on the extraction of three chlorobenzenes（CBs： 1,3-DCB, 1,2-DCB and 1,2,4-TCB; DCB=dichlorobenzene; TCB=trichlorobenzene） in fish samples. The results show that there was a strong binding effect between CB and FSA. In an aqueous solution of 90%（volume fraction） acetone, a slow but full protein denaturation might take place, which would cause the unfolding of protein and the releasing of CBs. Based on these results, a QuEChERS（quick, easy, cheap, effective, rugged and safe） method was modified by replacing the traditional acetonitrile with acetone aqueous solution in the present work. This modified QuEChERS method was applied in the determination of CBs in fish samples. The spiked recoveries and the limits of detection were 80.4%--118.3% and 2.4--7.3 ng/g, respectively. This paper proposes a new strategy by slowing down the protein denaturation and releasing bound organic compounds to enhance the extraction efficiency of CBs in fish samples.     

悬浮固化分散液液微萃取-高效液相色谱法测定水体中邻苯二甲酸酯

建立了悬浮固化分散液液微萃取（SFO-DLLME）结合高效液相色谱（HPLC）快速测定水样中6种邻苯二甲酸酯（PAEs）的分析方法。通过对影响萃取效率因素的优化,确定了最佳萃取条件：十二烷醇萃取剂20 μL、萃取温度60℃、离子强度20 g/L、萃取时间1 min。6种PAEs在2~2000 μg/L范围内呈良好的线性关系,相关系数（r）为0.9995~0.9999,检出限（S/N=3）为0.3~0.6 μg/L。对自来水、湖水、江水、污水、海水、市售塑料瓶装纯净水和矿泉水进行测定,能检测到部分PAEs。对加标水样进行回收率试验（10、100和1000 μg/L）,6种PAEs的回收率为84.9%~94.5%,相对标准偏差为4.1%~6.8%（n=5）。该法环保、简单,可用于实际水样中6种PAEs的检测分析。     

乙腈-无机盐-水双水相体系萃取-气相色谱法检测鱼肉中拟除虫菊酯

以乙腈-无机盐-水双水相体系,建立了一种环保、高效的用于气相色谱法检测鱼肉样品中拟除虫菊酯的样品前处理方法.实验利用荧光猝灭法与气相色谱法研究了拟除虫菊酯药物在以蛋白质为主要基质的水产品中的存在状态,考察了双水相的形成条件,并探讨了蛋白质对双水相萃取率的影响.结果表明,拟除虫菊酯药物通过疏水作用力与蛋白质牢固结合.以体积分数为80%的乙腈水溶液作为萃取液可以引起水产品中的蛋白质基质缓慢而彻底地变性,从而充分释放与蛋白质结合的药物,实现拟除虫菊酯的均相高效萃取.80%的乙腈水溶液具有较强的化学极性,因而在双水相系统上相中与药物残留共同萃入的脂溶性杂质较少,萃取液净化步骤大大简化.在双水相上相中加入无水MgSO4,PSA去除水分与杂质后,直接进样进行气相色谱检测.该方法用于鱼肉样品中六种拟除虫菊酯的萃取检测,回收率为81.1%～96.4%,检出限为8～14ng·mL-1.     

PDMS Rod-SBSE System Coupled with Gas Chromatography for Determination of PAHs in Aqueous Samples

A method for the analysis of trace polycyclic aromatic hydrocarbons(PAHs) in aqueous samples has been established by polydimethylsiloxane(PDMS) rod aided stir bar sorptive extraction(SBSE). The homemade PDMS rod has a size of 30 mm?3 mm o.d. with a volume of ca. 200 ?L, stable in thermal desorption process. The enriched PAHs by the PDMS rod were released in a homemade thermal desorption system coupled with gas chromatography. Experimental parameters for extraction of six PAHs were optimized including extraction time, pH, ionic strength and temperature of solution. The procedure has good recoveries of 80.0%―100.3% and very low limits of detection of 4.0―33 ng/L. PAHs in rain and river water were analyzed by this method.     

Successive Determination of Picogram Amounts of Phosphorus and Arsenic in Pure Water by Indirect Flameless Atomic Absorption (Mo) Spectroscopy

Abstract

The method involves the conversion of the P and As into the yellow 12-molybdo-phosphate or - arsenate complex, respectively, extraction into butyl acetate (in the case of As - with the preliminary addition of ethanol), the decomposition of the heteropoly-compounds with aqueous NH₃ and the back extraction of the liberated Mo into aqueous solution, for flameless AA determination. 10 pg P and 25 pg As in 0.4 ml samples of ultrapure water were determined with percentage errors below ±30%.     

Dispersive Liquid-liquid Microextraction for Simultaneous Determination of Six Parabens in Aqueous Cosmetics

A simple and rapid sample preparation method of dispersive liquid-liquid microextraction（DLLME） was applied in the simultaneous determination of six parabens in the aqueous cosmetics. The analysis was performed on gas chromatography coupled with a flame ionization detection（GC-FID）. The mixed solution containing 30 μL of chloroform（extraction solvent） and 300 μL of tetrahydrofuran（dispersive solvent） was rapidly injected into the sample solution for the purpose of microextraction. After that, the solution mentioned above was centrifuged at 4000 r/min for 10 min, and then the organic sediment phase was detected by GC-FID. The effects of experimental parameters, such as the extraction solvent and the volume of it, and the dispersive solvent and the volume of it, on the yield of the extraction were studied in detail. Under the optimum conditions, the enrichment factors of the target analytes range from 87 to 214. Linearity ranges are 0.05-10.0μg/mL for methylparaben and 0.025--5.0 μg/mL for the other five parabens. The relative standard deviations（RSDs） are lower than 8.2%（n=6）. The proposed method was applied to the analysis of six parabens in eleven aqueous cosmetics. The recoveries of the target analytes in the spiked real samples are in the range of 81.0%-103%.     

Determination of Carbamate Pesticides and Phthalates in Vegetables by a Cloud Point Extraction Process Using Tergitol 15-s-7 and High Performance Liquid Chromatography

An efficient and environmentally friendly analytical process based on cloud point extraction (CPE) has been developed for the determination of carbamate pesticides and phthalates in vegetables by high performance liquid chromatography (HPLC) separation and ultraviolet detection (UV). The readily biodegradable nonionic surfactant Tergitol 15-S-7 was chosen as the extraction solvent. To obtain optimum extraction efficiency, several experimental parameters including surfactant concentration, salt concentration, equilibration temperature, equilibration time, and sample pH were identified. Under the optimum conditions, the linear regression coefficients of the standard curves were greater than 0.9984. The limits of detection for carbaryl, pirimicarb, dimethyl phthalate (DMP), and diethyl phthalate (DEP) are 0.003, 0.015, 0.012, and 0.006 µg mL^?1, respectively. The intra-day and inter-day relative standard deviations are less than 5.75% and 6.97%. The proposed method has been proven to be an efficient, green, rapid, and inexpensive approach for extraction and determination of target analytes present in vegetable samples.     

Extraction of cobalt(Ⅱ) from aqueous solution by N,N'-carbonyl difatty amides

The development of economic and environmentally friendly extractants to recover cobalt metal is required due to the increasing demand for this metal.In this study,solvent extraction of Co(Ⅱ) from aqueous solution using a mixture of N,N’-carbonyl difatty amides(CDFAs) synthesised from palm oil as the extractant was carried out.The effects of various parameters such as acid,contact time,extractant concentration,metal ion concentration and stripping agent and the separation of Co(Ⅱ) from other metal ions such as Fe(Ⅱ),Ni(Ⅱ),Zn(Ⅲ) and Cd(Ⅱ) were investigated.It was found that the extraction of Co(Ⅱ) into the organic phase involved the formation of 1:1 complexes.Co(Ⅱ) was successfully separated from commonly associated metal ions such as Fe(Ⅱ),Ni(Ⅱ),Zn(Ⅲ) and Cd(Ⅱ).Co(Ⅱ) stripping from the loaded organic phase was studied in aqueous solution.These results are useful to recover Co(Ⅱ) from aqueous solution utilising(CDFAs) as an extractant.     

Ionic Liquid-based Microwave-assisted Liquid-liquid Microextraction and High Performance Liquid Chromatography Determination of Sulfonamides from Animal Oils

The authors performed ionic liquid-based microwave-assisted liquid-liquid microextraction(IL-based MALLME) coupled with high performance liquid chromatographic separation for the determination of 6 sulfonamides (SAs) from animal oils. The target analytes were extracted from animal oil samples with sodium hydroxide solution containing 1-butyl-3-methylimidazolium tetrafluoroborateand as the extraction solvent under microwave irradiation. The experimental parameters of the IL-based MALLME, including types of ILs, volume of IL, amount of ion-pairing agent(NH₄PF₆), pH value of sample solution, and extraction temperature and time were evaluated. The limits of detection and quantification obtained were in a range of 0.4―0.5 μg/kg and a range of 1.2―1.8 μg/kg, respectively. The accuracy of the method was evaluated by analyzing five spiked animal oil samples at two fortified levels(5 and 50 μg/kg), and the recoveries of SAs varied from 81.4% to 114.5% with relative standard deviations ranging from 0.8% to 9.0%.     

Determination of Phenolics in Water and Arthrospira (Spirulina) platensis by Concentrated Sulfuric Acid and Ultrasound-Assisted Surfactant-Enhanced Emulsification Microextraction and High Performance Liquid Chromatography

A novel, practical, and environmentally friendly technique, termed concentrated sulfuric acid cleanup and ultrasound-assisted surfactant-enhanced emulsification microextraction (CSAC-UASEM), was combined with HPLC for the preconcentration and determination of five phenolics in water and Arthrospira (Spirulina) platensis samples. The main advantages include that the concentrated sulfuric acid is used to decrease macromolecular interferences prior to microextraction and, unlike dispersive liquid–liquid microextraction procedures, no dispersive organic solvent is required. Chloroform and sodium dodecyl sulfate were used as the extraction solvent and emulsifier, respectively. The algal cell preparation and CSAC-UASEM procedure parameters, including selection of cleanup method, ultrasound power, cell cytocylasis time, type and volume of extraction solvent, extraction temperature, ultrasound-extracted time, and sample pH, were optimized. At the fortification levels of 1.0 and 10.0 µg/L, the enrichment factors of analytes were in the range of 201.38 to 269.24. The percent extraction ranged from 71.57% to 107.42% in environmental Arthrospira-350, -793, and -834 samples, whereas the range was from 74.17% to 106.72% in water samples. The limits of detection (at S/N = 3) were 0.02 to 0.04 µg/L (except for 4-bromobisphenol A of 0.10 µg/L). These values indicate an approximately ten-fold improvement compared with the values reported by other techniques. In summary, the CSAC-UASEM sample preparation technique has great potential in the routine determination of trace phenolics in environmental waters and aquatic biological samples.     

水相衍生-气相色谱-质谱法同时测定水产品中甲基汞和无机砷

建立了同时测定水产品中甲基汞和无机砷的水相衍生-气相色谱-质谱联用分析方法。采用6 mol/L盐酸超声辅助提取水产品中的甲基汞与无机砷,于-10℃冷冻离心后,提取液中的无机砷（As³⁺与As⁵⁺）与2,3-二巯基丙醇（BAL）溶液于35℃水浴中衍生反应30 min,用甲苯萃取衍生物与甲基汞,萃取前加入无水乙醇避免非脂成分进入有机相中,向甲苯萃取液中添加甲基汞的衍生剂四苯硼钠溶液（pH 3.6）。采用选择离子监测（SIM）模式,外标法测定水产品中的甲基汞与无机砷。结果表明,水产品中甲基汞与无机砷在5～2000 μg/L范围内线性关系良好,相关系数（r）均大于0.999;检出限为0.7～3 μg/kg （S/N=3）。在10、100、1000 μg/kg加标水平下,方法加标回收率为80.0%～110.0%,相对标准偏差（n=6）为2.5%～9.4%。该方法操作简便、准确、灵敏度高,已成功应用于水产品中无机砷与甲基汞的食品污染物风险监测中。     

Implementation of solid-phase microextraction with micellar desorption method for priority phenolic compound determination in natural waters

Eleven phenolic compounds considered by the Environmental Protection Agency to be priority pollutants are extracted and determined in different water samples. The method involves the extraction and clean-up step of target compounds by solid-phase microextraction and micellar desorption (SPME-MD) and a second step of determination by liquid chromatography with diode array detection. Different fibers and surfactants are evaluated for the analysis of these target analytes in water samples. In the optimum conditions for the SPME process, recoveries for the target compounds are between 80% and 109%; relative standard deviations are lower than 10%, and detection limits are in the range 0.3-3.5 ng/mL. The main advantages of this method are the combination of time and efficiency, safety, and an environmentally friendly process for sample extraction prior to instrumental determination. This demonstrates that SPME-MD can be used as an alternative to traditional methods for the extraction and determination of priority phenolic compounds in natural waters from different origins.     

Isolation and Extraction of Total Flavonoids from Epimedium Koreanum Nakai by Supercritical Fluid Extraction

In the present paper is reported the metnocl for the isolation and extraction of total flavonoids of Epimedium Koreanum Nateai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed bydynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.     

Stir-bar sorptive extraction based on hydroxyl-functionalized zirconium-metal-organic framework for the detection of three quinolones in actual samples

A novel analytical method based on stir-bar sorptive extraction was proposed for the determination of three trace quinolones in fish and shrimp samples. UiO-66-(OH)₂, a hydroxyl-functionalized zirconium metal-organic framework, has been coated on frosted glass rods by an in situ growth method. The product, UiO-66-(OH)₂ modified frosted glass rods, has been characterized and key parameters have been optimized in combination with ultra-high-performance liquid chromatography. The detection limits of enoxacin, norfloxacin, and ciprofloxacin were 0.48–0.8 ng ml⁻¹, and the detection concentrations were in the range of 10–300 ng ml⁻¹, showing a good linear relationship. This method was used for the determination of three quinolones in aquatic organisms, and the recoveries in spiked fish and shrimp muscle tissue samples were 74.8%–105.4% and 82.5%–115.8%, respectively. The relative standard deviations were less than 6.9%. The established method combined stir-bar sorptive extraction based on UiO-66-(OH)₂ modified frosted glass rods with ultra-high-performance liquid chromatography, has good application prospects for the detection of quinolone residues in fish and shrimp muscle samples.     

Preparation and evaluation of molecularly imprinted solid-phase micro-extraction fibers for selective extraction of phthalates in an aqueous sample

A novel molecularly imprinted polymer (MIP) that was applied to a solid-phase micro-extraction (SPME) device, which could be coupled directly to gas chromatograph and mass spectrometer (GC/MS), was prepared using dibutyl phthalate (DBP) as the template molecule. The characteristics and application of this fiber were investigated. Electron microscope images indicated that the MIP-coated solid-phase micro-extraction (MI-SPME) fibers were homogeneous and porous. The extraction yield of DBP with the MI-SPME fibers was higher than that of the non-imprinted polymer (NIP)-coated SPME (NI-SPME) fibers. The MI-SPME fibers had a higher selectivity to other phthalates that had similar structures as DBP. A method was developed for the determination of phthalates using MI-SPME fibers coupled with GC/MS. The extraction conditions were optimized. Detection limits for the phthalate samples were within the range of 2.17-20.84 ng L⁻¹. The method was applied to five kinds of phthalates dissolved in spiked aqueous samples and resulted in recoveries of up to 94.54-105.34%, respectively. Thus, the MI-SPME fibers are suitable for the extraction of trace phthalates in complicated samples.     

Determination of Polycyclic Aromatic Hydrocarbons in Tobacco Smoke by Ionic Liquid Enrichment and Gas Chromatography – Mass Spectrometry

A rapid, efficient and environmentally friendly method based on the ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]) was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in mainstream tobacco smoke. This technique combined ionic liquid (IL) enrichment with solvent reverse extraction for the replacement of solid phase extraction and rotary evaporation in the traditional method and enriched PAHs in the organic solvent. Several parameters, including the type of ionic liquid, volume of ionic liquid and water, extraction time, vortex time and reverse extraction time, were optimized. After pretreatment, the analytes were analyzed by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring (SIM). Satisfactory results were achieved when this method was applied to determine PAHs in mainstream tobacco smoke. The calibration curves were linear with correlation coefficients ranging from 0.9955 to 0.9999 at concentration levels of 10–800?µg?L^?1, and the relative standard deviations of the optimized method were between 0.7% and 5.3%. The limits of detection were 0.01–0.6?ng cig^?1, and the recoveries of the compounds were 80.2–118%. A comparison of this protocol with literature methods demonstrated that the proposed procedure provides accurate and reliable sample-treatment for the determination of PAHs in tobacco samples.     

Air-assisted liquid–liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples

A novel air assisted liquid–liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μg L⁻¹. The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3–13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.     

高效液相色谱-紫外检测法同时测定食品接触材料中7种苯多酸及其衍生物的特定总迁移量

建立了高效液相色谱-紫外检测(HPLC-UV)同时测定5种食品模拟物(10%(v/v)乙醇、20%(v/v)乙醇、50%(v/v)乙醇、3%(w/v)乙酸和橄榄油)中偏苯三甲酸、偏苯三甲酸酐、间苯二甲酰氯、间苯二甲酸、对苯二甲酰氯、邻苯二甲酸、对苯二甲酸的特定总迁移量(SML(T))的方法。用食品模拟物浸泡待测样品,冷却至室温并混匀,水基食品模拟物经亲水性聚四氟乙酸针头过滤器过滤后进样;橄榄油用0.1%(w/v)乙酸铵水溶液提取后,下层清液用亲水性聚四氟乙烯针头过滤器过滤后进样。用Synergi Polar-RP色谱柱(250 mm×4.6 mm, 4 μm)分离,梯度洗脱,检测波长为232 nm。5种食品模拟物中的定量限为0.1~0.2 mg/kg;水基食品模拟物在0.5~12 mg/L、橄榄油食品模拟物在0.5~12 mg/kg范围内线性关系良好(r² > 0.99991); 1.25、2.5、6.25 mg/kg水平的加标回收率为94.3%~105%,相对标准偏差为0.1%~2.3%。结果表明,该方法的色谱分离和线性关系较好,回收率和准确度高,完全满足欧盟(EU)No 10/2011法规附表2中7种苯多酸及其衍生物的SML(T)的限量要求,并已应用于实际样品的检测。     

Efficient separation and recovery of V(V) from Cr(VI) in aqueous solution using new task-specific ionic liquid of [C12H25NH3][Cyanex 272]

An environmentally friendly process for efficient separation and recovery of V(V) from aqueous solution containing Cr(VI) was proposed using the new task-specific ionic liquid of [C₁₂H₂₅NH₃][Cyanex 272]. The separation factor of V(V) from Cr(VI) was about 1.08 × 10³ with the optimum extraction conditions, and the extraction percentage of V(V) was about 99.5 %. The loaded organic phase was stripped using the NH₃·H₂O, and the recovered NH₄VO₃ was obtained with the processes of stripping, filtration, washing, and desiccation. The qualitative analysis of the recovered NH₄VO₃ was made using the X-ray diffraction, and its peaks were good consistent with the standard sample. Morphology of the recovered NH₄VO₃ was also studied using the scanning electron microscope. The extraction mechanism of V(V) using the [C₁₂H₂₅NH₃][Cyanex 272] was investigated using the slope method and infrared spectrum analysis. This new environmentally friendly process can be used for the separation and recovery of V(V) from real leaching solution with the aim of industrial application.     

Determination of four acidic nonsteroidal anti‐inflammatory drugs in wastewater samples by dispersive liquid–liquid microextraction based on solidification of floating organic droplet and high‐performance liquid chromatography

A simple, environmentally friendly, and sensitive dispersive liquid–liquid microextraction based on solidification of floating organic droplet for the extraction of four acidic nonsteroidal anti‐inflammatory drugs (ketoprofen, naproxen, ibuprofen, and diclofenac) from wastewater samples subsequent by high‐performance liquid chromatography analysis was developed. The influence of extraction parameters such as pH, the effect of solution ionic strength, type of extraction solvent, disperser solvent, and extraction solvent volume were studied. High enrichment factors (283–302) were obtained through the developed method. The method provides good linearity (r > 0.999) in a concentration range of 1–100 μg/L, good intra‐ and inter‐day precision (relative standard deviation < 7%) and low limits of quantification. The relative recoveries of the selected compounds were situated over 80% both in synthetic and real water samples. The developed method has been successfully applied for the analysis of the selected compounds in wastewater samples.