液液萃取-气相色谱-质谱联用法测定饮用水中19种农药残留量

提出了液液萃取富集-气质联用法测定饮用水中19种农药的残留量。样品用二氯甲烷萃取3次(20,10,10mL),萃取液合并后旋转蒸发至1.0mL,分取1.0μL进样,进行气相色谱-质谱分析。用HP-5MS毛细管柱分离及电子轰击离子源,用离子检测扫描模式做质谱测定。用菲-d_(10)作内标,峰面积定量。19种农药在一定浓度范围内呈线性,检出限(3S/N)为0.002～0.10mg·L~(-1)之间,回收率在81.1%～103.0%之间,相对标准偏差(n=6)为0.25%～7.7%。     

Determination of Barium in Bottled Drinking Water by Graphite Furnace Atomic Absorption Spectrometry

Abstract

In relation to the wide environmental spread of barium and to its cardiovascular effects, barium levels were determined by graphite furnace atomic absorption spectrometry in 60 different brands of bottled water marketed in Italy.

Matrix interferences were investigated in order to evaluate the use of an analytical calibration function rather than the much more time consuming addition technique.

The barium content ranged from limit of detection C_L (7.0 μg/l) up to 660 μg/l, the median value being 80 μg/l, while the recovery tests varied between 90 and 110 % and the precision of the method (s_yx) was 2.5 %.     

石墨炉原子吸收光谱法测定生活饮用水中砷的方法优化

建立了石墨炉原子吸收光谱(GFAAS)法测定生活饮用水中砷的方法。升压放电空心阴极灯的使用,降低了基线噪声水平和检出限。对温度程序、化学基体改进剂和热稳定剂进行了优化并用于GFAAS测定砷,无需进行初步处理。研究结果显示,线性方程为y=0.005 62x+0.000 04,相关系数R为0.998 3,样品体积为16μL时的检出限为0.26μg/L。加标回收率为98.1%～99.2%,相对标准偏差5%。取实际饮用水样验证了其适用性。     

石墨炉原子吸收光谱法测定生活饮用水中砷的方法优化

建立了石墨炉原子吸收光谱(GFAAS)法测定生活饮用水中砷的方法。升压放电空心阴极灯的使用,降低了基线噪声水平和检出限。对温度程序、化学基体改进剂和热稳定剂进行了优化并用于GFAAS测定砷,无需进行初步处理。研究结果显示,线性方程为y=0.005 62x+0.000 04,相关系数R为0.998 3,样品体积为16μL时的检出限为0.26μg/L。加标回收率为98.1%～99.2%,相对标准偏差<5%。取实际饮用水样验证了其适用性。     

一种高灵敏测定水中游离氯的新方法

探讨了在中性水溶液中，游离氯催化过氧化氢氧化副攻瑰苯胺的褪色反应及其动力学条件，建立了一种高灵敏、选择性好测定水中痕量Ｃｌ２的新方法，测定范围为０．０１５￣１．０μｇ／１０ｍｌ，成功地用于水中Ｃｌ２的测定。     

Biodegradation analyses of trichloroethylene (TCE) by bacteria and its use for biosensing of TCE

Trichloroethylene (TCE) is a toxic, recalcitrant groundwater pollutant. TCE-degrading microorganisms were isolated from various environments. The aerobic bacteria isolated from toluene- and tryptophan-containing media were Pseudomonas sp. strain ASA86 and Burkholderia sp. strain TAM17, respectively; these are necessary for inducing TCE biodegradation in a selective medium. The half-degradation time of TCE to a concentration of 1 mg/L was 18 h for strain ASA86 and 7 days for strain TAM17. While identifying toluene/TCE degradation genes, we found that in strain ASA86, the gene was the same as the todC1 gene product encoding toluene dioxygenase identified in Pseudomonas putida F1, and that in strain TAM17, the gene was similar to the tecA1 gene product encoding chlorobenzene dioxygenase identified in Burkholderia sp. PS12. A novel TCE biosensor was developed using strain ASA86 as the inducer of toluene under aerobic conditions. The TCE biosensor exhibited a linear relationship below 3 ppm TCE. Detection limit of the biosensor was 0.05 ppm TCE. The response time of the biosensor was less than 10 min. The biosensor response displayed a constant level during a 2 day period. The TCE biosensor displayed sufficient sensitivity for monitoring TCE in environmental systems.     

固相萃取-气相色谱-质谱法测定饮用水中36种农药残留量

提出了固相萃取-气相色谱-质谱联用法测定饮用水中36种农药的残留量。样品用石墨化碳/氨基复合型小柱净化和富集后,经DB-1701P弹性石英毛细管柱分离,用电子轰击离子源及选择离子监测扫描模式进行质谱测定。36种农药在一定浓度范围内呈线性关系,检出限(3S/N)在0.001 3～0.070mg.L-1之间。按方法在水样的基础上加入农药混合标准溶液做回收试验,测得回收率在90.8%～112.4%之间,测定值的相对标准偏差(n=5)在3.20%～13.2%之间。     

低温富集液液萃取-气相色谱-串联质谱法测定水样中15种农药残留

利用低温冷冻条件下农药在水相和有机相之间达到新的传质平衡,建立了低温富集液液萃取-气相色谱-三重四极杆串联质谱法同时测定水样中15种有机磷、有机氯及菊酯类农药的方法。通过对样品前处理中的溶剂选择、冷冻温度及冷冻时间的优化,最终确定的样品前处理条件为:萃取溶剂为甲苯2.0 mL;冷冻温度-40℃;冷冻时间1h。15种农药的检出限(3S/N)在0.005~0.02μg·L-1范围,测定下限(10S/N)为0.02~0.07μg·L-1。方法用于水样中农药的分析,加标回收率在78.8%~124%之间,测定值的相对标准偏差(n=5)在0.9%~9.1%之间。     

饮用水中挥发性有机物(VOCs)的GC-MS分析

用顶空－毛细管气相色谱－质谱联用仪测定了北京主要区域的自来水,北京目前市场销售的瓶装饮用水（包括天然矿泉水,纯净水等）中２３种挥发性有机物（ＶＯＣｓ）（包括有机氯化物,有机溴代物及苯系物等）的浓度,并与其它城市（如天津,上海,兰州等地）的自来水中ＶＯＣｓ的浓度进行了比较,结果表明北京市区内自来水及大多数市售瓶瓶饮用水中ＶＯＣｓ含量很低。     

顶空固相微萃取-气相色谱-质谱法测定饮用水源水中1,3,5-三氯苯

采用顶空固相微萃取-气相色谱-质谱法对饮用水源水中1,3,5-三氯苯进行了测定。以1,2-二氯苯-d4为内标,用PDMS萃取头顶空萃取20min,萃取头于气相色谱进样口解析5min。采用DB-624色谱柱在程序升温条件下进行分离,质谱分析中采用电子轰击离子源(230℃,70eV)及选择离子监测模式测定。结果表明:1,3,5-三氯苯在0.100～2.50μg.L-1范围内呈线性,检出限(3S/N)为0.019μg.L-1。方法用于河流及水库水中的1,3,5-三氯苯的测定,加标回收率在91.5%～126.0%之间。     

饮用水中痕量溴酸盐分析方法的研究进展

溴酸盐是用臭氧对饮用水进行消毒时产生的一种副产物,是一种潜在的致癌物。本文介绍了溴酸盐的形成、危害以及分析方法等,并着重对近年来溴酸盐的分析方法进行了详细的综述。     

A Validated LC Method for the Quantitation of Cefotaxime in pH-Sensitive Nanoparticles

A sensitive and rapid routine LC method was validated for measuring cefotaxime incorporated in three different pH-sensitive nanoparticles. The drug was chromatographed on a C18 reversed-phase column; the mobile phase used was 0.05 M aqueous ammonium acetate, acetonitrile and tetrahydrofuran (87:11:2, v/v) adjusted to pH 5.5 with acetic acid. The flow rate was 1 mL min^?1 and cefotaxime was quantified at 254 nm, with a sensitivity range of 0.005 AUFS. The validated method was specific, linear (R ² ≥ 0.999), precise and accurate in a concentration range of 0.2–50.0 μg mL^?1. The method was rapid, selective and suitable for evaluation of cefotaxime in pH-sensitive Eudragit nanoparticles.     

南昌大学（北区）饮用水中As,Se,Hg,Zn,Fe等无机元素的研究

从南昌大学和水的Ａｓ、Ｈｇ、Ｐｂ、Ｃｄ、Ｓｅ、Ｚｎ等１０种无机元素的测定研究入手，论述了这些无机元素与人体的关系。并将南昌大学的饮用水和南昌市市区饮用水与生活用水水质标准进行对比，证明南昌大学的饮用水并未污染。     

微溶剂萃取-气相色谱-质谱法测定水中邻苯二甲酸二(2-乙基己基)酯

取水样25mL,加入无水硫酸钠3.0g,加入环己烷2.0mL,振荡萃取3min。移取萃取了邻苯二甲酸二(2-乙基己基)酯(DEHP)的上层有机相2.0μL注入HP-5毛细管柱(30m×0.32mm,0.25μm)色谱分离后进行质谱测定。DEHP的质量浓度在50.0μg.L-1以内与其峰面积呈线性关系,方法的检出限(3S/N)为0.052μg.L-1。分析了早、中、晚不同时间的天津市自来水,并用标准加入法做回收试验,测得回收率在97.0%～109.4%之间,测定值的相对标准偏差(n=6)均小于2.5%。     

生活饮用水经餐具煮沸后金属元素含量分析

采用火焰原子吸收法测定了生活饮用水经不同餐具煮沸后金属元素Ｋ，Ｎａ，Ｃａ，Ｍｇ含量的变化，结果显示，自来水在煮沸２０ｍｉｎ后，４种金属元素含量均明显升高，而以经铝制高压锅和搪瓷锅煮后的中元素含量升高明显，而以经铁锅煮后水中元素含量升高最低，但各元素含量均在正常范围之内，长期饮用不会对健康产生明显影响。     

Optimizing conditions for the extraction of catechins from green tea using hot water

Six different factors involved in the extraction of catechins from green tea using water were examined for their impact on the yield of catechins and on the efficiency of water use. The best temperature and time combination for catechin extraction was at 80°C for 30 min. The yield of catechins was also optimal with a tea particle size of 1 mm, a brewing solution pH <6 and a tea‐to‐water ratio at 50:1 (mL/g). In terms of efficient use of water in a single extraction, a water‐to‐tea ratio of 20:1 (mL/g) gave the best results; 2.5 times less water was used per gram of green tea. At the water‐to‐tea ratio of 20:1 mL/g, the highest yield of catechins per gram of green tea was achieved by extracting the same sample of green tea twice. However, for the most efficient use of water, the best extraction was found to be once at a water‐to‐tea ratio of 12:1 (mL/g) and once at a water‐to‐tea ratio of 8:1 (mL/g). Therefore, all six of the factors investigated had an impact on the yield of catechins extracted from green tea using water and two had an impact on the efficiency of water use.     

Water as a green solvent combined with different techniques for extraction of essential oil from lavender flowers

Using water as a green solvent with a variable geometry makes use of physical and chemical phenomena that are fundamentally different from those applied in conventional extraction techniques such as hydro-distillation, steam distillation or solvent extraction. Advantages and drawbacks of using water as a solvent with different physical and chemical states have been compared. A total of ten extraction techniques: hydro-distillation (HD), steam distillation (SD), turbo-hydro-distillation (THD), salt-hydro-distillation (NaCL-HD), enzyme-hydro-distillation (Enzyme-HD), micelle-hydro-distillation (Micelle-HD), ultrasound-hydro-distillation (US-HD) or subcritical water-hydro-distillation (SW-HD), solvent-free microwave extraction (SFME) and microwave steam distillation (MSD) were used to extract the essential oil from lavender (Lavandula L.) and their results were compared. The quantity was measured by the yield of essential oil and the quality was evaluated using the oil composition especially the content of linalyl acetate, linalool and terpin-4-ol compared with the corresponding control sample: Hydro-distillation. For environmentally friendly of the process: extraction time, total energy consumption and CO₂ emission were considered and compared with conventional hydro-distillation. The mechanism explaining the linalyl acetate degradation has been resolved by using COSMO-RS software. Based on the present experimental conditions, it is recommended that lavender oil may be produced preferably by steam distillation assisted by microwave extraction to reduce the by-product formation by various chemical reactions and to get better oil recoveries.     

OH与TCE和PCE加成中间体消除反应的机理

用从头计算法在UHF/6-31G水平研究了羟基自由基与三氯乙烯和四氯乙烯形成的加成中间体的消除反应,通过振动分析确认了过渡态,计算了内禀反应坐标(IRC).研究表明,该反应消除一个氯化氢分子,形成具有平面构型的另一个中间体,反应活化势垒较低,分别为79.84kJ mol-1和62.68kJ mol-1,且二者反应在常温常压下是熵增、放热、吉布斯自由能ΔGΘ<Ο,具有较大自发趋势的过程。     

一阶导数吸光光度法直接测定饮用水中镁

研究了以甲基百里香酚蓝（MTB）作显色剂，在pH作10.0的NH4Cl-氨缓冲溶液中，用一阶导数吸光光度法测定饮用水中镁的最佳条件。以617nm波长处的零－谷导数值定量，用零交技术可消除钙等干扰。线性范围为0－15μg/25ml，加标回收率在98％－107％之间。经过对饮用水样的测定，并与其它分析方法比较，结果满意。     

Determination of Cu2+ in Drinking Water Based on Electrochemiluminescence of Ru(phen)32+ and Cyclam

A convenient and simple electrochemiluminescence (ECL) method was employed to detect trace amounts of Cu²⁺ in drinking water. This method is based on the inhibitory effect of Cu²⁺ on the ECL of Ru(phen)₃²⁺ and 1,4,8,11‐tetraazacyclotetradecane (cyclam) system. ECL intensity of Ru(phen)₃²⁺ was considerably enhanced by the addition of cyclam because of the ECL reaction between them. The ECL intensity of Ru(phen)₃²⁺/cyclam system rapidy decreased with the addition Cu²⁺ because of the formation of chelate complex [Cu(cyclam)]²⁺. Good linear response (R ²=0.9948) was obtained at Cu²⁺ concentration of 1.0×10⁻⁹−1.0×10⁻⁵ mol ⋅ L⁻¹ at glassy carbon electrode in 0.1 mol ⋅ L⁻¹ phosphate buffer (pH 9.0). Observed detection limit of 4.8×10⁻¹⁰ mol ⋅ L⁻¹ satisfied the maximum contaminant level goal (MCLG) for Cu²⁺ set by the US Environmental Protection Agency (US EPA). Applicability of the proposed method was verified by the good reproducibility and stability of the method when applied to determine Cu²⁺ in tap water and simulated wastewater. Thus, a novel ECL detection method was developed for Cu²⁺ detection.