Trace analysis of diethylstilbestrol, dienestrol and hexestrol in environmental water by Nylon 6 nanofibers mat-based solid-phase extraction coupled with liquid chromatography-mass spectrometry

A simple, rapid and sensitive method for the determination of diethylstilbestrol (DES), dienestrol (DE) and hexestrol (HEX) was developed by using the Nylon 6 nanofibers mat-based solid-phase extraction (SPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS). These estrogens were separated within 8 min by LC using an ODS column and methanol/water (80/20, v/v) at a flow rate of 1.0 mL min(-1). Electrospray ionization conditions in the negative ion mode were optimized for MS detection of the estrogens. Under the optimum SPE conditions, all target analytes in 50 mL environmental water samples can be completely extracted by 1.5 mg Nylon 6 nanofibers mat at flow rate of 3.0 mL min(-1) and easily eluted by passage of 500 μL mobile phase. By using the novel SPE-LC/MS method, good linearity of the calibration curve (r(2) ≥ 0.9992) was obtained in the concentration range from 0.10 ng L(-1) to 1.0 mg L(-1) (except for DE which was 0.20 ng L(-1) to 1.0 mg L(-1)) for all analytes examined. The limits of detection (S/N = 3) of the three estrogens ranged from 0.05 ng L(-1) to 0.10 ng L(-1). This method was applied successfully to the analysis of environmental water samples without any other pretreatment and interference peaks. Several water samples were collected from Jinchuan River and Xuanwu Lake, and in Jinchuan River water DES was detected at 0.13 ng L(-1). The recoveries of estrogens spiked into tap water were above 98.2%, and the relative standard deviations were below 4.78%.     

Multiresidue analysis of polar pesticides in surface and drinking water by on-line enrichment and thermospray LC-MS

In the search for a fast and robust sample handling and preparation step to analyse various pesticides at trace levels in aqueous samples, an on-line trace enrichment has been combined with our thermospray LC-MS method [1] allowing both selective identification and a quantification down to the lower ng/L level. 51 polar pesticides were investigated by applying solid phase extraction to 50–100 ml aqueous samples using small cartridges filled with 40 mg adsorbent. Prior to their liquid chromatographic separation, the enriched analytes were eluted from the solid phase with the initial methanol/water gradient composition of the HPLC onto the analytical column using column switching techniques. A base-deactivated C₁₈ material and the two styrene-divinylbenzene copolymers PLRP-S and PRP-1 were tested for enrichment in combination with a C₈-bonded silica analytical column. The method developed was evaluated with respect to recoveries, precision, limits of detection and linearity. Furthermore, it was applied to various environmental samples. Apart from a few compounds of higher polarity, most of the pesticides show recoveries >60% (often >80%) with relative standard deviations between 1–15%. Overall method detection limits are in the range of 1–100 ng/L allowing, with one exception, a ready verification of the pesticide limit of 100 ng/L set in the EU drinking water guideline [2].     

Picogram determination of estrogens in water using large volume injection gas chromatography–mass spectrometry

In this study, a simple and efficient large volume injection gas chromatography–mass spectrometry (GC-MS) method, via a programmable-temperature vaporizer (PTV) inlet, has been developed and applied in the determination of estrogens in environmental water samples without a prior derivatization process. Three commonly used estrogens estrone, 17 β-estradiol and 17 α-ethynylestradiol were selected as target compounds for this study. It has been demonstrated that the type of gas chromatograph liner and the initial inlet temperature can greatly affect the response intensity of estrogens. Three different types of PTV liners have been studied; the multibaffle liner generated the strongest response intensities towards the estrogen analytes. The results showed that the response intensities of estrogens reduced sharply while the initial inlet temperature increased. Various instrument conditions and sample preparation methods were studied in detail. The optimized method has been validated with good linearity, precision and accuracy. The method detection limit of each estrogen was found to be 0.041 ng/L for estrone, 0.046 ng/L for 17 β-estradiol and 0.031 ng/L for 17 α-ethynylestradiol. To the best of our knowledge, these results represent the best sensitivities achieved for estrogens analyzed in water samples via traditional GC-MS method without a derivatization process. This method has been successfully applied in the analyses of different water samples.     

Analysis of polycyclic aromatic hydrocarbons in water and beverages using membrane-assisted solvent extraction in combination with large volume injection-gas chromatography-mass spectrometric detection

Membrane-assisted solvent extraction (MASE) in combination with large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was applied for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The MASE conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of extraction conditions (shaking speed, extraction temperature and time), extraction solvent and composition (ionic strength, sample pH and presence of organic solvent). Parameters like linearity and reproducibility of the procedure were determined. The extraction efficiency was above 65% for all the analytes and the relative standard deviation (RSD) for five consecutive extractions ranged from 6 to 18%. At optimized conditions detection limits at the ng/L level were achieved. The effectiveness of the method was tested by analyzing real samples, such as river water, apple juice, red wine and milk.     

李晶1,2, 徐济仓1, 李雪梅1, 周建光2, 朱岩3, 缪明明1*超高效液相色谱法同时测定香精香料中14种禁限用物质

建立了超高效液相色谱-二极管阵列检测器(UPLC-PDA)同时测定香精香料中14种禁限用物质的方法。样品经10%(v/v)甲醇水溶液(含1%(v/v)氨水)提取后进行UPLC测定。采用的色谱柱为Waters BEH C18柱(50 mm×2.1 mm, 1.7 μm),流动相为10 mmol/L乙酸铵(含0.1%乙酸)和乙腈,梯度洗脱,流速为0.2 mL/min,柱温为35 ℃,在200～500 nm范围内进行扫描检测。结果表明,该方法在12 min内可实现14种禁限用物质的分离和检测,在0.10～50 mg/L范围内具有较好的线性关系,各待测物的线性相关系数均大于0.995,检出限(以信噪比为3计)为0.32～2.51 mg/kg。在5、10、20 mg/L添加水平下待测物的平均回收率为93.0%～121.0%,相对标准偏差为0.51%～4.50%。该方法操作简易,灵敏度高,线性相关性好,重复性佳,可以满足国内对于香精香料样品中禁限用物质的检测要求。     

Loading controlled magnetic carbon dots for microwave‐assisted solid‐phase extraction: Preparation,extraction evaluation and applications in environmental aqueous samples

An adsorbent of carbon dot@poly(glycidyl methacrylate)@Fe₃O₄ nanoparticles has been developed for the microwave‐assisted magnetic solid‐phase extraction of polycyclic aromatic hydrocarbons in environmental aqueous samples prior to high‐performance liquid chromatography with UV/visible spectroscopy detection. Poly(glycidyl methacrylate) was synthesized by atom transfer radical polymerization. The chain length and amount of carbon dots attached on them can be easily controlled through changing polymerization conditions, which contributes to tunable extraction performance. The successful fabrication of the nano‐adsorbent was confirmed by transmission electronic microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and vibrating sample magnetometry. The extraction performance of the adsorbent was evaluated by using polycyclic aromatic hydrocarbons as model analytes. The key factors influencing the extraction, such as microwave power, adsorption time, desorption time and desorption solvents were investigated in detail. Under the optimal conditions, the microwave‐assisted method afforded magnetic solid‐phase extraction with short extraction time, wide dynamic linear range (0.02–200 μg/L), good linearity (R² ≥ 98.57%) and low detection limits (20–90 ng/L) for model analytes. The adsorbent was successfully applied for analyzing polycyclic aromatic hydrocarbons in environmental aqueous samples and the recoveries were in the range of 86.0–124.2%. Thus, the proposed method is a promising candidate for fast and reliable preconcentration of trace polycyclic aromatic hydrocarbons in real water samples.     

固相萃取-分散液液微萃取-柱前衍生法测定水样中痕量雌激素

建立了碳纳米管的固相萃取-分散液液微萃取-柱前荧光衍生化(SPE-DLLME-PFD)测定水体中痕量雌三醇(E3)、双酚A(BPA)、17α-乙炔基雌二醇(EE2)及17β-雌二醇(E2)的高效液相色谱方法.采用中心复合设计和响应曲面法分析并优化SPE、DLLME及PLD条件,最佳条件为210 mL水样以2.0 mL/min的流速过固相萃取柱(碳纳米管量30 mg),甲醇洗脱,氮气浓缩并定容至0.6 mL(分散剂),将100 μL C6MIM[PF6]与分散剂的混合液注入到NaCl含量为25％的2.0 mL去离子水中,离心,移取20 μL下层有机相于样品瓶中,与4.0 mg衍生剂混合,在40℃水浴中衍生25 min;用0.1mL甲醇溶解过量的衍生剂颗粒,取20 μL进样分析.在优化条件下.4种雌激素的线性范围为0.05～5.00 μg/L,相关系数R2=0.9966～0.9999;,检出限介于0.13～6.33 ng/L(S/N=3)之间.不同加标浓度条件下,雌激素的加标回收率在83.1％～122.4％范围内(RSD=1.7％～9.6％).在实际水样中E3和BPA检出率较高.与其它方法相比,本方法虽然萃取时间长、水样量大、步骤多,但具有检出限低、操作简便、环境友好等优点.     

流动注射在线预富集-高效液相色谱法测定四种硝基类化合物

建立了以香烟过滤嘴纤维作吸附剂,在线固相萃取-高效液相色谱（SPE—HPLC）测定水中邻硝基苯甲酸、对硝基苯胺、邻硝基苯酚、3-氯硝基苯四种硝基类化合物的方法。邻硝基苯甲酸、对硝基苯胺、邻硝基苯酚、3-氯硝基苯分别在0．006～4．80、0．003～2．40、0．002～1．60、0．002～1．60mg／L范围内峰面积与浓度呈线性关系,相关系数分别为0．9994、0．9996、0．9997和0．9996;检出限（S／N=3）分别为1．0、0．8、0．6,0．6μg／L;富集倍数分别为28．2、176．6、172．1、153．3。该法用于河水中四种硝基类化合物的测定,回收率为85．41％～116．44％,相对标准偏差在1．1％～5．4％范围内。     

液相色谱-串联质谱法同时测定动物血浆中21种霉菌毒素或其代谢物残留

建立了同时检测动物血浆中黄曲霉毒素B1等21种霉菌毒素或其代谢物残留的液相色谱-串联质谱方法.动物血浆样品中加入0.1％甲酸-乙腈溶液、NaCl和无水MgSO4进行萃取,无水MgSO4和C18,PSA,A-AL对提取液进行脱水净化,经浓缩、复溶和离心后,再进行测定.采用反相C18色谱柱分离,以0.1％甲酸-0.5 mmol/L乙酸铵溶液和0.1％甲酸-甲醇溶液作为流动相进行梯度洗脱,采用电喷雾离子源(ESI)多反应监测离子模式(MRM)进行检测,基质标准曲线外标法进行定量分析,线性范围在0.05 ～ 100 ng/mL之间,方法的定量限为0.05 ～0.5 ng/mL.在高、中、低3个添加浓度水平下,21种霉菌毒素的平均回收率为62.0％ ～ 116.4％,相对标准偏差小于19％.     

Solid-phase extraction using molecularly imprinted polymer for selective extraction of natural and synthetic estrogens from aqueous samples

A method is proposed for the clean-up and preconcentration of natural and synthetic estrogens from aqueous samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). The selectivity of the MIP was checked toward several selected natural and synthetic estrogens such as estrone (E1), 17β-estradiol (β-E2), 17α-estradiol (α-E2), estriol (E3), 17α-ethinylestradiol (EE2), dienestrol (DIES) and diethylstilbestrol (DES). Ultrahigh pressure liquid chromatography (UHPLC) coupled to a TSQ triple quadrupole mass spectrometry (QqQ) was used for analysis of target analytes. The chromatographic separation of the selected compounds was performed in less than 2 min under isocratic conditions. The method was applied to the analysis of estrogens in spiked river and tap water samples. High recoveries (>82%) for estrone, 17β-estradiol, 17α-estradiol, estriol and 17α-ethinylestradiol were obtained. Lower but still satisfactory recoveries (>48%) were achieved for dienestrol and diethylstilbestrol. The method was validated and found to be linear in the range 50-500 ng L(-1) with correlation coefficients (R(2)) greater than 0.995 and repeatability relative standard deviation (RSD) below 8% in all cases. For analysis of 100-mL sample, the method detection limits (LOD) ranged from 4.5 to 9.8 ng L(-1) and the limit of quantitation (LOQ) from 14.9 to 32.6 ng L(-1). To demonstrate the potential of the MIP obtained, a comparison with commercially available C(18) SPE was performed. Molecularly imprinted SPE showed higher recoveries than commercially available C(18) SPE for most of the compounds. These results showed the suitability of the MIP-SPE method for the selective extraction of a class of structurally related compounds such as natural and synthetic estrogens.     

Rapid analysis of triazolopyrimidine sulfoanilide herbicides in waters and soils by high-performance liquid chromatography with UV detection using a C18 monolithic column

In this work, the simultaneous analysis of five triazolopyrimidine sulfoanilide herbicides (flumetsulam, florasulam, metosulam, cloransulam-methyl, and diclosulam) by HPLC using UV detection and a C18 monolithic column is proposed. The mobile phase which was composed of ACN, water, and formic acid was pumped at a high flow rate (5 mmL/min) providing an analysis time of all the compounds in less than 2.3 min. The LODs were in the low microg/L range (i.e. between 60 microg/L for flumetsulam and 90 microg/L for florasulam) and the calibration curves showed good linearity (R2 > 0.9949). The method was applied to the analysis of these compounds in spiked mineral and tap waters and soils after an SPE preconcentration procedure using C18 cartridges. Mean recovery values ranged between 35 and 110% for water samples providing LODs of the whole procedure in the low ng/L level, down to 280 ng/L, and between 77 and 92% for soil samples with LODs down to 9.38 microg/kg. This is the first time that this family of pesticides is simultaneously analyzed in both types of samples by HPLC and also using a monolithic column.     

Magnetic mixed hemimicelles solid‐phase extraction coupled with high‐performance liquid chromatography for the extraction and rapid determination of six fluoroquinolones in environmental water samples

In this study, a mixed hemimicelle solid‐phase extraction method based on Fe₃O₄ nanoparticles coated with sodium dodecyl sulfate was applied for the preconcentration and fast isolation of six fluoroquinolones in environmental water samples before high‐performance liquid chromatography determination. The main factors affecting the extraction efficiency of the analytes, such as amount of surfactant, amount of Fe₃O₄ nanoparticles, extraction time, sample volume, sample pH, ionic strength, and desorption conditions, were investigated and optimized. The method has detection limits from 0.05 to 0.1 ng/mL and good linearity (r ≥ 09948) in the range 0.1–200 ng/mL depending on the fluoroquinolone. The enrichment factor is ～200. The recoveries (at spiked levels of 1, 5, and 50 ng/mL) are in the range of 79–120%.     

Polyacrylic acid-modified alumina for solid-phase extraction and preconcentration of trace iron and chromium from plant samples

A new method is presented for simultaneous preconcentration of trace Fe(III) and Cr(III) by using polyacrylic acid-alumina as a sorbent. The separation/preconcentration conditions of analytes were investigated, including effect of pH, flow rate, elution conditions, sample volume, and interfering ions. At pH 4, the maximum sorption capacities of Fe3+ and Cr3+ were 8.0 and 13.0 mg/g, respectively, by the column method. The linearity was maintained in the concentration range of 0.175-6.0 x 10(3) ng/mL for iron and 0.175-8.0 x 10(3) ng/mL for chromium in the original solution. The RSD values under optimum conditions were +/- 1.73 and +/- 1.28% for 2.0 microg/mL Fe and Cr, respectively. The preconcentration factor was 400 for both of the elements, and detection limits were 0.025 and 0.023 ng/mL for Fe and Cr in the original solutions. The proposed method was successfully applied to the determination of trace amounts of Fe and Cr in plant samples.     

Liquid‐phase microextraction based on two immiscible organic solvents followed by gas chromatography with mass spectrometry as an efficient method for the preconcentration and determination of cocaine,ketamine, and lidocaine in human urine samples

A new type of liquid‐phase microextraction based on two immiscible organic solvents was optimized and validated for the quantification of lidocaine, ketamine, and cocaine in human urine samples. A hollow‐fiber based microextraction technique followed by gas chromatography coupled with mass spectrometry detection was used to reduce matrix interferences and improve limits of detection. The analytes were extracted from aqueous sample with pH 11.0, into a thin layer of organic solvent (n‐dodecane) sustained in the pores of a hollow fiber, and then into a second organic acceptor (acetonitrile) located inside the lumen of the hollow fiber. With the application of optimized values, good linearity was obtained in the range of 1–500 μg/L for lidocaine and ketamine and 2–500 μg/L for cocaine with the determination coefficient values (r²) >0.9943. The preconcentration factors and limits of detection (S/N > 3) were 250–350 and 0.01–0.05 μg/L, respectively. Intra and interassay precision values were <7.3 and 9.3%, respectively. The method was successfully applied for the determination and quantification of target analytes in human urine samples.     

Electromembrane extraction of gonadotropin‐releasing hormone agonists from plasma and wastewater samples

In the present study, for the first time electromembrane extraction followed by high performance liquid chromatography coupled with ultraviolet detection was optimized and validated for quantification of four gonadotropin‐releasing hormone agonist anticancer peptides (alarelin, leuprolide, buserelin and triptorelin) in biological and aqueous samples. The parameters influencing electromigration were investigated and optimized. The membrane consists 95% of 1‐octanol and 5% di‐(2‐ethylhexyl)‐phosphate immobilized in the pores of a hollow fiber. A 20 V electrical field was applied to make the analytes migrate from sample solution with pH 7.0, through the supported liquid membrane into an acidic acceptor solution with pH 1.0 which was located inside the lumen of hollow fiber. Extraction recoveries in the range of 49 and 71% within 15 min extraction time were obtained in different biological matrices which resulted in preconcentration factors in the range of 82–118 and satisfactory repeatability (7.1 < RSD% < 19.8). The method offers good linearity (2.0–1000 ng/mL) with estimation of regression coefficient higher than 0.998. The procedure allows very low detection and quantitation limits of 0.2 and 0.6 ng/mL, respectively. Finally, it was applied to determination and quantification of peptides in human plasma and wastewater samples and satisfactory results were yielded.     

Pipette‐tip solid‐phase extraction using cetyltrimethylammonium bromide enhanced molybdenum disulfide nanosheets as an efficient adsorbent for the extraction of sulfonamides in environmental water samples

Surfactant cetyltrimethylammonium bromide enhanced molybdenum disulfide was used as an adsorbent in pipette‐tip solid‐phase extraction for the pretreatment of sulfonamides in environmental water samples. The factors affecting the extraction recoveries of the analytes, including the sample pH value, amount of sorbent, type and volume of eluent solution, and salt concentration were optimized. This pipette‐tip solid‐phase extraction method demonstrated good linearity (0.05–10.0 µg/L) with a coefficient of determination of 0.9984–0.9996, limit of detection (0.2–0.4 ng/L) and limit of quantitation (0.5–1.0 ng/L), good analyte recoveries (76–91), and acceptable limit of quantitation (<10%) under the optimized conditions. These results indicated that the proposed method was a good tool for monitoring sulfonamides in environmental water samples.     

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

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

Ionic liquid-based dispersive liquid-liquid microextraction for sensitive determination of aromatic amines in environmental water

Ionic liquid-based dispersive liquid-liquid microextraction was developed for the extraction and preconcentration of aromatic amine from environmental water. A suitable mixture of extraction solvent (100 μL, 1-butyl-3-methylimidazolium hexafluorophoshate) and dispersive solvent (750 μL, methanol) were injected into the aqueous samples (10.00 mL), forming a cloudy solution. After centrifuging, enriched analytes in the sediment phase were determined by HPLC-UV. The effect of various factors, such as the extraction and dispersive solvent, sample pH, extraction time and salt effect were investigated. Under optimum conditions, enrichment factors for 2-anilinoethanol, o-chloroaniline and 4-bromo-N,N-dimethylaniline were above 50 and the limits of detection (LODs) were 0.023, 0.015 and 0.026 ng/mL, respectively. Their linear ranges were 0.8-400 ng/mL for 2-anilinoethanol, 0.5-200 ng/mL for o-chloroaniline and 0.4-200 ng/mL for 4-bromo-N,N-dimethylaniline, respectively. Relative standard deviations (RSDs) were below 5.0%. The relative recoveries from samples of environmental water were in the range of 82.0-94.0%. Compared with other methods, dispersive liquid-liquid microextraction is simple, rapid, sensitive and economical.     

Graphene‐based solid‐phase extraction disk for fast separation and preconcentration of trace polycyclic aromatic hydrocarbons from environmental water samples

Graphene has great potentials for the use in sample preparation due to its ultra high specific surface area, superior chemical stability, and excellent thermal stability. In our work, a novel graphene‐based SPE disk was developed for separation and preconcentration of trace polycyclic aromatic hydrocarbons from environmental water samples. Based on the strong π–π stacking interaction between the analytes and graphene, the analytes extracted by graphene were eluted by cyclohexane and then determined by GC‐MS. Under the optimized conditions, high flow rate (30 mL/min) and sensitivity (0.84–13 ng/L) were achieved. The proposed method was successfully applied to the analysis of real environmental water samples with recoveries ranging from 72.8 to 106.2%. Furthermore, the property of anticlogging and reusability was also improved. This work reveals great potentials of graphene‐based SPE disk in environmental analytical.     

在线固相萃取净化-液相色谱-串联质谱法测定猪肉中10种大环内酯类抗生素

建立了在线固相萃取净化-液相色谱-串联质谱检测猪肉中10种大环内酯类抗生素残留的方法。样品经过乙腈提取,提取液40℃旋蒸至干后,分析物用2 mL磷酸盐缓冲液溶解,溶解液经在线固相萃取柱(HLB柱)富集净化,甲醇洗脱,然后转移至XBridge BEH C18色谱柱上,以10 mmol/L乙酸铵水溶液和乙腈溶液为流动相进行分离,最后用串联四极杆质谱检测。结果表明,10种大环内酯类抗生素在0.1~200μg/L范围内呈现良好的线性关系,相关系数均大于0.990。方法的检出限范围为0.05~0.30μg/kg,定量限范围为0.10~1.00μg/kg;添加水平为0.10~10.0μg/kg时,方法回收率为69.6%~115.2%,相对标准偏差(RSD)10%。该方法可以作为猪肉中大环内酯类抗生素的检测方法。