二噁英类物质CALUX报告基因法在造纸行业的应用探究

选择典型造纸厂,采用化学激活报告基因法(CALUX)测定造纸过程中废水和纸浆中的二噁英类物质,并将部分样品测定结果与高分辨气相色谱-高分辨质谱(HRGC-HRMS)法测定结果作线性回归,换算系数为0.21,表明CALUX可用于造纸行业废水中二噁英类物质的快速筛查。将CALUX用于测定造纸厂废水中二噁英类物质,结果表明用含元素氯的漂白工艺会产生大量二噁英类物质,其中漂白废水中的目标物毒性当量浓度最高,经处理后可达到国家排放标准;而用无元素氯的漂白工艺,二噁英类物质的产生量会大幅降低。     

Polychlorinated biphenyls (PCBs) analysis using a miniaturized high-resolution time-of-flight mass spectrometer "MULTUM-S II"

In this study, we conducted polychlorinated biphenyls (PCBs) analysis using fast gas chromatography (GC)/high-resolution mass spectrometry (HRMS). Mass spectrometry (MS) was performed with a miniature multi-turn time-of-flight (TOF) analyzer called "MULTUM-S II". MULTUM-S II is truly a portable high resolution mass spectrometer. The mass spectrometer's high resolution capability is due to its theoretical infinite flight path utilizing perfect space and time focusing within a closed flight orbit. Mass resolution above 10?000 was easily achievable employing this portable system. This mass resolution is comparable to magnetic sector mass spectrometers, which have traditionally performed PCB analyses in the past. At a resolution of 10?000, a limit-of-detection of 1 ppb was determined using a heptachlorinated biphenyl standard sample. Using this fast GC/HRMS, 66 PCB congeners were analyzed within 5 min. In addition experiments aimed at confirming interference of PCB signal peaks and matrix peaks in diluted dielectric coolant fluids were performed. We found that the PCB signal peaks were detected without matrix interference via high mass resolution.     

Evaluation of the methyl ester O-methyl acetate derivative of muramic acid for the determination of peptidoglycan in environmental samples by ion-trap GC-MS-MS

Muramic acid (MA) is a unique amino sugar that is a constituent of the peptidoglycan (PG) present in prokaryotic cell walls. MA can serve as a marker for quantifying bacterial load, e.g. in indoor environments, by using gas chromatography-tandem mass spectrometry (GC-MS-MS). We demonstrated recently that the methyl ester O-methyl acetate (MMA) derivative can be used to detect MA in house dust by ion-trap GC-MS-MS. However, since the MMA derivative is not formed from free MA quantification was not optimal. Here we report 1) significant improvements in sample preparation of the MMA derivative and 2) an evaluation of the performance of derivative, using for comparison the alditol acetate derivative, the gold standard in quantitative trace analysis of MA in complex matrices. The MMA derivative was analysed using an MS instrument with internal ionization and the alditol acetate derivative was analysed using an instrument with external ionization. 13C-labelled cyanobacteria, containing MA in their PG, were used as the internal standard. A linear relationship was found between the two methods in studies on 27 parallel samples of airborne dust from school classes collected on filters. Although the analytical sensitivity of the MMA derivatives was somewhat slightly lower than of the alditol acetate derivative, this may be due to differences in yield of derivative, sample clean-up efficiency, or different performance of the GC columns or MS instruments. However preparation of the MMA derivative is quick and compatible with preparation of methyl esters of 3-hydroxy fatty acids (used as markers of Gram negative endotoxin) allowing the levels of both markers to be determined in the same dust sample. In conclusion, the MMA procedure can be used to determine MA in environmental samples with good reproducibility provided the concentration of the 13C-labelled MA internal standard in the cyanobacteria is first determined with an alternative method.     

A pilot study on the determination of perfluorooctanesulfonate and other perfluorinated compounds in blood of Canadians

A pilot study was conducted to provide preliminary data on the concentrations of perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorooctanesulfonamide (PFOSA) in the blood of Canadians. A set of 56 human serum samples was collected from non-occupationally exposed Canadians and analyzed by microbore HPLC-negative ion electrospray tandem mass spectrometry. PFOS was the main component of perfluorinated organic compounds (PFCs) and was detected in all 56 blood specimens at an average concentration of 28.8 ng mL(-1) and a range from 3.7 to 65.1 ng mL(-1). The concentration of PFOA was an order of magnitude lower than that of PFOS and was found only in 16 samples (29%) at concentrations above the limit of quantification (LOQ). PFOSA was not detected at levels above the method detection limit (MDL) in any of the samples. The levels of PFCs observed in the sample group of non-occupationally exposed humans in Canada were similar to the levels reported in a previous US study with a similar sample pool size. Two distinct PFOS isomers in human serum were identified by accurate mass determination.     

测定游离氯和总氯样品保存方法研究

建立了游离氯和总氯样品保存方法。用氢氧化钠溶液作为固定剂,现场固定含有游离氯和总氯的水样,使水样pH>12。结果表明,样品经4℃低温避光保存,5 d内测定,测量结果没有显著变化,方法检出限(以Cl2计)为0.004mg/L,加标回收率为96.7%～104%。     

便携式GC-MS仪快速测定水中硝基苯及其在应急监测中的应用

采用便携式GC-MS仪快速测定水中硝基苯,通过优化水中离子强度和顶空加热时间,使方法在0μg/L^300μg/L范围内线性良好,方法检出限为2.5μg/L。标准溶液6次测定结果的RSD为7.8%~10.9%,实际水样的加标回收率为80.7%~103%。同步测定试验表明,硝基苯与7种苯系物分离良好。与国标方法对比,该方法单个样品测定时间由2 h缩短为15 min。将该方法用于应急监测工作中,及时有效的数据可为污水处理及事故调查提供分析和研判依据。     

吹扫捕集-气相色谱/质谱法同时测定水中的27种挥发性有机物

水中的VOCs经吹扫富集、解吸后,用HP-VOC色谱柱分离,采用全扫描和选择离子监测模式分析,内标法定量。最佳富集条件为:吹扫流速为40 m L/min,吹扫温度为40℃,吹扫时间为15 min,解吸温度为200℃,解吸时间为2 min。该法27种VOCs在一定的质量浓度范围内与其峰面积呈线性关系,相关系数r0.995,检出限为0.02~1.18μg/L。以空白样品为基体进行加标回收试验,测得回收率为79.8%~114%,相对标准偏差为0.3%~12%。     

Oxidation of Cr(III) to Cr(VI) during chlorination of drinking water

Drinking water treatment typically uses strong oxidants such as chlorine which are capable of converting Cr(III) to Cr(VI). The rates and extent of Cr(III) oxidation by chlorine are not well established. Cr(III) oxidation experiments were therefore conducted in distilled deionized water and New York City tap water dosed initially with Cr(III) and supplemented with sodium hypochlorite to increase free chlorine residual. Reaction progress was monitored using capillary electrophoresis which quenched reactions and allowed for quantification of Cr(VI). Three different forms of Cr(III) were used as reactants: a Cr(III) nitrate salt, Cr(III)-EDTA, and Cr(III) hydroxide. Rates of Cr(VI) production for all three forms of Cr(III) were rapid, on the order of hours. However, oxidation rates slowed and a plateau in Cr(VI) concentrations was reached. This resulted in less than 100% conversion of Cr(III) to Cr(VI) even at relatively high chlorine doses (10 to 100 mg L(-1) as Cl(2)). The loss of free chlorine due to a non-Cr chlorine demand, the precipitation of Cr(III) to Cr(OH)(3)(s), and the partial oxidation of Cr(III) to intermediate oxidation states (i.e. Cr(IV) and Cr(V)) were examined and eliminated as possible explanations for this behavior. Consumption of chlorine via reaction with intermediate oxidation states of Cr is therefore offered as a possible explanation for the plateau in Cr(VI) concentrations.     

液相色谱-串联质谱法同时测定污水中10种精神活性物质

建立了采用液相色谱-串联质谱法(LC-MS/MS)同时测定污水中10种精神活性物质的分析方法。污水样品经甲酸与甲酸铵调节pH后,加入氘代内标混匀,离心并过滤膜后可直接上样分析。研究表明,在1~250 ng/L的线性范围内,10种精神活性物质的线性相关系数均大于0.992,定量限均低于0.5 ng/L。在3个加标水平下,10种精神活性物质的加标回收率为87.2%~114%,相对标准偏差为0.53%~3.60%(n=3)。将该方法应用于某区域10份生活污水样品的检测,在3份水样中检出吗啡、甲基苯丙胺、氯胺酮等精神活性物质,对应的质量浓度范围分别为3.41~9.55、0.90~1.63、1.06~1.78 ng/L。与经固相萃取前处理后的分析方法相比,该方法可在10 min内完成分离和检测的全过程,具有简单、快速、节约的优点,可用于污水样品中10种痕量水平精神活性物质的定量分析。     

Identification of surfactant degradation products as toxic organic compounds present in sewage sludge

A cost-effective strategy combining chemical analysis and bioassays for the identification of polar toxic compounds in sewage sludge is reported. ToxAlert 100 bioluminescence inhibition assay was used in combination with chemical analysis involving extraction, clean-up, chromatographic separation and mass spectrometry detection. This methodology was applied to real samples of sludge from three wastewater treatment plants (WWTP) located in Catalonia (Spain) during a 3 month period. In the first step, sewage sludge was lyophilized, treated by sonication with a mixture of methanol and chloroform and finally cleaned up using a sequential solid phase extraction (SSPE) with an octadecylsilica cartridge (C18) in series with a polymeric Lichrolut EN cartridge (Lic EN). In the second step, the toxicity of each fraction of the sludge sample was investigated using the ToxAlert 100. The unequivocal identification and quantification of polar organic cytotoxic substances present in the fractionated extracts were determined by liquid chromatography-mass spectrometry (LC-MS). Major toxic compounds identified were: non-ionic polyethoxylated surfactants (nonylphenol polyethoxylates, alcohol polyethoxylates), their intermediates (polyethylene glycol polyethoxylated, nonylphenol carboxylates and polyethoxylated alcohol carboxylates), linear alkylbenzenesulfonates and heavy metals. The toxic response (in terms of bioluminescence inhibition using ToxAlert 100), defined by the 50% effective concentration (EC50), and the toxicity units (TU) for every standard non-ionic surfactant were calculated. The results provided the identification of polar cytotoxic compounds as well as the evaluation of their contribution to the total toxicity observed in sewage sludge.     

True and false positive rates in maximum contaminant level tests

The U.S. Environment Protection Agency (EPA) is promulgating a revised national primary drinking water regulation (NPDWR) which includes a monthly sample size and maximum contaminant level (MCL) for total coliform bacteria in public water systems. No previous quantification has been made of the coliform content that must be present in the sampled water in order for an MCL to be exceeded. This paper presents a method for evaluating the coliform level an MCL will detect with likelihood P.Our approach is to treat an MCL as a decision rule, with Type I (false positive) and Type II (false negative) error rates. The stringency of an MCL is quantified as the mean coliform level in the sampled system that it will detect with likelihood P. MCLs are contrasted on stringency by comparing the mean coliform level each targets for detection, with fixed error rates.Interim rules (NIPDWR), in effect since 1975, are shown to vary widely on the coliform content each targets for detection, that is, on stringency. Yes/no decisions on contamination have not been decided based on mean coliform content. Coliform levels permitted in monitored public water systems have been determined by the particular MCL used for testing. The same coliform level will test positively with one MCL 90 times in 100 yet be guaranteed 95% nondetection by a second MCL.EPA's reasonably safe standard for drinking water is reformulated on our stringency criteria. Its proposed monthly MCL is evaluated on its capability for maintaining this standard. Smaller systems will not provide its users this level of protection under the new rule.In addition, our evaluation of the safe water standard on stringency and the rationale for a monthly MCL require that coliform levels be identically distributed (i.d.) across month and sampled system. Empirical data strongly refute this model and question the utility of a monthly MCL.This work suggests an alternative, single sample MCL, with repeat sampling for verification, which can be configured to provide monitoring to discover mean coliform values at any level, in any size of system, at minimal extra cost.     

便携式GC-MS快速测定水中苯胺

采用便携式GC-MS测定水体中的苯胺,并对水样中离子强度和顶空分析的平衡时间进行优化。试验表明,苯胺在10．0μg/L～200μg/L范围内有较好的线性,r为0．998;方法检出限为5．8μg/L;回收率为92．8％～96．7％;RSD为3．2％～8．6％。用54种VOCs混合标样对苯胺标液进行干扰试验,结果试验条件下苯胺与VOCs得到有效分离。     

Causes of temporal variability of lead in domestic plumbing systems

Sources of lead in drinking water are primarily lead pipe, lead/tin solder, and brass fixture materials.Lead levels in the water depend upon many solubility factors, such as pH, concentrations of substances such as inorganic carbonate, orthophosphate, chlorine, and silicate, the temperature, the nature of the pipe surface, etc. Physical factors, time, and chemical mass transfer are significant in governing lead levels in nonequilibrium systems. The diameter and length of lead pipe is extremely important, as well as the age and chemical history of the solder and brass fixtures. Analytical variability is not particularly significant relative to between-site and within-site variability. Knowledge of temporal variability at each site is necessary to define a statistically valid monitoring program. An analysis of published data covering repetitive measurements at a given site show that the variability of lead concentration at each site tends to be characterized by the frequent occurrence of spikes. Variability expressed as approximate relative standard deviations tends to be of about 50 to 75% in untreated water, regardless of the mean lead concentration. The distributions are frequently nonnormal for small numbers of samples. Monitoring programs must incorporate controls for the causes of the within-site and between-site variability into their sampling design. The determination of necessary sampling frequency, sample number, and sample volume must be made with consideration of the system variability, or the results will be unrepresentative and irreproducible.     

The role of GC-MS and LC-MS in the discovery of drinking water disinfection by-products

Gas chromatography-mass spectrometry (GC-MS) has played a pivotal role in the discovery of disinfection by-products (DBPs) in drinking water. DBPs are formed when disinfectants, such as chlorine, ozone, chlorine dioxide or chloramine, react with natural organic matter in the water. The first DBP known--chloroform--was identified by Rook in 1974 using GC-MS. Soon thereafter, chloroform and other trihalomethanes were found to be ubiquitous in chlorinated drinking water. In 1976, the National Cancer Institute published results linking chloroform to cancer in laboratory animals, and an important public health issue was born. Mass spectrometry and, specifically, GC-MS became the key tool used for measuring these DBPs in water and for discovering other DBPs that were formed. Over the last 25 years, hundreds of DBPs have been identified, mostly through the use of GC-MS, which has spawned additional health effects studies and regulations. Early on, GC with low resolution electron ionization (EI)-MS was used, together with confirmation with chemical standards, for identification work. Later, researchers utilized chemical ionization (CI)-MS to provide molecular weight information and high resolution El-MS to aid in the determination of empirical formulae for the molecular ions and fragments. More recently, liquid chromatography-mass spectrometry (LC-MS) with either electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) has been used to try to uncover highly polar DBPs that most experts believe have been missed by earlier GC-MS studies. Despite 25 years of research in the identification of new DBPs, new ones are being discovered every year, even for chlorine which has been the most extensively studied.     

离子色谱法测定地表水中总氮

采用碱性过硫酸钾消解水样,OnGuardⅡBa柱萃取、过滤,去除消解液中大量硫酸盐,离子色谱法测定地表水中总氮含量。试验表明,方法在0ms／L～20．0mg／L之间线性良好,相关系数r为0．9994,方法检出限为0．007mg／L。该方法与国标法同时测定标准物质,测定值均在定值范围内,6次平行测定结果的RSD分别为2．3％和1．8％,地表水样的加标回收率为95．7％～105％。实际水样的测定结果与国标法比对,无明显差异。     

Monitoring of Coliforms and chlorine residual in water distribution network of Rawalpindi, Pakistan

The present study was undertaken to examine the drinking water quality of Rawal Treatment Plant, Rawalpindi and its distribution network by collecting samples from eight different locations. The aim was to determine potential relationship between the presence of microorganisms and chlorine residual in the distribution network. Quantification of chlorine residual, turbidity, standard plate count (SPC), fecal and total coliforms by Most Probable Number (MPN) was performed. Three different forms of chlorine were measured at each sampling station such as free chlorine, residual chlorine, chloramines and total chlorine residual. A critical evaluation of data presented indicated that pH generally ranged from 7.02–7.30; turbidity varied from 0.34–2.79 NTU; conductivity fluctuated from 359–374 μS/cm; and TDS values were found to be ranging between 180–187 mg/l. Station # 7 was found to be most contaminated. The value of total chlorine was found to be 0.86 to1.7 mg/l at Station # 3 and 6, respectively. Highest standard plate count was 62 CFU/ml at Station # 7. Total coliforms were less than 1.1 MPN/100 ml at almost most of the stations except at Station # 3 where it was found to be greater than 23.0 MPN /100 ml. Overall aim of this study is to create awareness about contamination of drinking water in the water distribution networks and to make recommendations to provincial agencies such as EPA, CDA and WASA that regular monitoring should be carried out to ensure that the chlorine residual is available at consumer end.     

高氯离子废水化学需氧量分析方法的研究

提出一种测定高氯离子废水 COD的新方法。其消解条件与现行国标法基本相同 ,消解过程产生的氯气用Na OH吸收并测定出氯离子的 COD校正值。由表观 COD值减去氯离子的 COD校正值 ,即为水样的真实 COD值。标样的相对误差在 -1.5 %～ 5 %之间 ,RSD%≤ 5 .5 %。高氯废水的 RSD%≤ 8.0 %。     

Potential Applications for Pyrolysis-GC/MS in Bioremediation

Preliminary data are presented from a set of experiments designed to promote the use of pyrolysis-GC/MS in bioremediation. Studies were designed to aid researchers in developing a pyrolysis-GC/MS method and identifying how the method could help characterize bioremediation, particularly in organic soils. Since sample size affects the results of pyrolytic analyses, the first experiment demonstrated how an appropriate sample size might be selected for pyrolysis-GC/MS testing. In order to show how quantitative results can be obtained from pyrolysis-GC/MS, a second experiment determined the 'goodness of fit' for a standard curve relating the chromatographic area under a pyrogram to actual mass units. The third experiment investigated ways in which pyrolysis-GC/MS analyses could improve our understanding of bioremediation in organic soils contaminated with crude oil. Experimental results confirmed that differences in analyte mass affect the extent of pyrolytic cracking. In pyrograms of the test soil, the ratio of toluene to total product showed that for a sample mass between 1.8 and 2.0 mg, variability in the cracking pattern was minimized. Unlike deviations outside this range, small deviations within the range did not appreciably effect the toluene ratio. A standard curve was prepared for pyrolytic analyses by plotting the total chromatographic area of all pyrolysis products versus the mass of organic material pyrolyzed. These data were fit with a straight line having an 'R²' of 0.73. Based on a bench scale bioremediation experiment, preliminary pyrolysis-GC/MS results were used to predict that compounds derived from lignin and carbohydrates would be degraded faster in uncontaminated than contaminated soils. Appreciable degradation of both compounds, however, occurred in contaminated soils. In addition, results suggested that using pyrolysis-GC/MS to quantify the sum of all n-alkanes and the ratio of odd to even chain n-alkanes could help researchers distinguish between the degradation of petroleum and non-petroleum hydrocarbons in contaminated and uncontaminated soils.     

Simultaneous determination of insecticide fipronil and its metabolites in maize and soil by gas chromatography with electron capture detection

An integrated method for the simultaneous determination of insecticide fipronil and its three metabolites, desulfinyl, sulfide, and sulfone, in maize grain, maize stem, and soil was developed. This three-step method uses liquid–solid extraction with ultrasound or mechanical grinding, followed by liquid–liquid partitioning and florisil solid-phase extraction (SPE) for cleanup. The quantification was conducted by gas chromatography–electron capture detection in triplicate for each sample. The method was validated with five replicates at three fortification concentrations, 0.002, 0.01, and 0.1 mg kg^?1, in each matrix and gave mean recoveries from 83 to 106 % with relative standard deviation ≤8.9 %. The limits of quantification (LOQ) were 0.002 mg kg^?1 for the compounds in all matrixes. In the field study in Beijing and Shandong 2012, fipronil-coated maize seeds were planted and the proposed method was applied for checking the possible existence of four compounds in maize and soil samples, but none of them contained residues higher than the LOQs in both application rates. Moreover, the dissipation of fipronil in soil fits first-order kinetics with half-lives 9.90 and 10.34 days in Beijing and Shandong, respectively. Combined with an adequate sample treatment, this technique offers good sensitivity and selectivity in the three complex matrixes. The results could provide guidance for the further research on pesticide distribution and safe use of fipronil as seed coat in cereals.     

On-line dechlorination–hydrogenation of chlorinated paraffin mixtures using GC and GC/MS

Chlorinated paraffins (CPs) are straight chain hydrocarbons that are produced as complex mixtures and are used as flame retardants and paint additives. These mixtures are extremely difficult to characterize using conventional chromatographic methods, as conventional gas chromatography results in unresolved complex chromatograms that preclude the identification and quantification of individual congeners or any reasonable assessment of the average carbon chain length. Carbon chain length is an important parameter for assessing physical properties and the toxicity of these materials. We have modified and improved a previously published gas chromatography–flame ionization detector method that uses Pd catalyst held in the gas chromatograph injector to simultaneously dechlorinate the CPs and separate the resulting alkanes. In addition, we have adapted this method to gas chromatography–mass spectrometry. Dehalogenation of other compounds was also studied with this system to investigate potential application to other complex halogenated mixtures.