顶空气相色谱法测定水中氯丁二烯

应用顶空气相色谱法测定饮用水及地表水中微量的氯丁二烯,色谱柱为HP-1,检测器为ECD。结果表明,所建立的方法对氯丁二烯的检出限为0.23μg/L,加标回收率为89.7%～97.7%,相对标准偏差为7.02%(n=10),适用于水中氯丁二烯的测定。     

生活饮用水中氯苯类化合物和溴氰菊酯的气相色谱法测定

建立了生活饮用水中氯苯类化合物和溴氰菊酯的气相色谱检测方法。该方法对1,3-二氯苯、1,4-二氯苯、1,2-二氯苯、1,3,5-三氯苯、1,2,4-三氯苯、1,2,3-三氯苯、1,2,3,5-四氯苯、1,2,4,5-四氯苯、1,2,3,4-四氯苯、五氯苯、六氯苯和溴氰菊酯的检出限分别为0.116,0.186,0.120,0.016,0.022,0.014,0.009,0.011,0.005,0.002,0.001和0.024μg/L,相对标准偏差为0.7%～3.2%,加标回收率为95%～105%。该方法可同时检测12种化合物,水样预处理简单,溶剂用量小,回收率高,精密度好且相互之间没有干扰。     

Direct analytical method for aliphatic compounds in water by steam carrier gas chromatography

Conditions for direct analyses of various aliphatic compounds in water by the recently developed steam carrier gas chromatography (SCGC) were studied using a hydrogen flame ionization detector and acid washed Chromosorb P modified with 3.5 ± 0.3 wt% of phosphoric acid as a stationary solid in 2 mm i.d. × 2 m glass column. A flowrate of approx. 60 ml min⁻¹ of carrier steam and a column temperature of 150–180°C were considered to be the optimum conditions for analysing water samples containing several groups of aliphatic compounds. The relationship between the retention time and the boiling point was obtained for two groups of soluble and slightly soluble compounds. The retention time of an aliphatic compound can, therefore, be predicted from its boiling point and solubility, and conversely, the compounds in an unknown sample can be characterized for identification from their retention times. The relative peak area increased proportionally with increase of the effective number of carbon atoms in the compound. By SCGC, various aliphatic compounds present in water at concentrations higher than approx. 40 μg 1⁻¹ can be analysed directly including some polar compounds which are difficult to analyze by conventional gas chromatography without complicated pre-treatment.     

Direct analytical method for aromatic compounds in water by steam carrier gas chromatography

Conditions for direct analyses of various aromatic compounds in water by steam carrier gas chromatography (SCGC) were studied by using a hydrogen flame ionization detector and acid washed Chromosorb P modified with 3.5 ± 0.3 wt% of phosphoric acid as a stationary solid in 2 mm i.d. × 2 m glass column. A flowrate of approx. 60 ml min⁻¹ of carrier steam and a column temperature of 150–180°C were considered to be the optimum conditions for analyses of water samples containing several groups of aromatic compounds. Under constant conditions, aromatic compounds were generally eluted in order of their boiling points. The relationship between the retention time and the boiling point was obtained for two groups of substitutes of benzene and naphthalene. The retention time of a substitute of benzene or naphthalene can, therefore, be predicted from its boiling point, and conversely, the aromatic compounds in an unknown water sample can be characterized for identification from their retention times. By SCGC, various aromatic compounds in water at concentrations higher than approx. 30 μg l⁻¹ can be analysed directly without complicated pre-treatment.     

Determination of trace low-molecular-weight volatile polar organics in water by gas chromatography using distillation method

The distillation technique has been investigated as a means of concentrating in the distillate the low-molecular-weight volatile polar organic compounds such as alcohols, ketones, and aldehydes in aqueous solution. The volatility of these compounds relative to that of water was found to be a useful parameter in determining the concentration of the respective compounds in the distillate. By directly injecting the distillate onto a gas chromatographic column, low-molecular-weight volatile polar organics can be determined quantitatively at the ppb level. The relative standard deviation for the distillation technique is approximately 5% based on triplicate runs using an internal standard. This study shows that the distillation technique is a simple, unique, and efficient method of concentrating low-molecular-weight volatile polar organics at the ppb level for subsequent gas chromatographic analysis.     

Analysis of trihalomethanes in drinking water using headspace-SPME technique with gas chromatography

In many drinking water treatment plants, the chlorination process is one of the main techniques used for the disinfection of water. This disinfecting treatment leads to the formation of trihalomethanes (THMs) such as chloroform, dichlorobromomethane, chlorodibromomethane and bromoform. In this study, headspace-solid-phase microextraction (HS-SPME, 85 microm carboxen/polydimethylsiloxane fiber) technique was applied for the analysis of THMs in drinking water. The effects of experimental parameters such as kinds of SPME fiber, the volume ratio of sample to headspace, the addition of salts, magnetic stirring, extraction temperature, extraction time and desorption time on the analysis were investigated. Analytical parameters such as linearity, repeatability and limit of detection were also evaluated. The results of THMs from the survey of Seongnam (Korea) drinking water samples showed that the highest total trihalomethane and chloroform were 24.03 and 13.34 microg/l, which were well within the Korean drinking water quality standard of 100 and 80 microg/l, respectively.     

New standards for the determination of geosmin and methylisoborneol in water by gas chromatography/mass spectrometry

Deuterium labelled geosmin and methylisoborneol (MIB) have been synthesized and evaluated as internal standards in the determination of geosmin and MIB in water by closed loop stripping followed by gas chromatography/mass spectrometry (GC/MS). The labelled standards were compared with chloroalkanes added as internal standards either at the time of sampling or immediately before closed loop stripping. When added at sampling time, the new standards enabled accurate determination of the geosmin and MIB present initially, even when the samples were analysed as much as 3 weeks later. The new standards gave better precision and accuracy than the chloroalkanes and overcame the underestimation of initial analyte concentration which usually results from losses of analyte through adsorption, volatilisation, biodegradation etc. during sample storage. Geosmin had a limit of detection of<0.1ng/l and 1 ng/lwas determined with a coefficient of variation (CV) of 1.2% (n = 5). MIB was determined at 1 ng/l with a CV of 3.5% (n = 5).     

Determination of dichloroacetic acid and trichloroacetic acid in drinking water by acidic methanol esterification and headspace gas chromatography

A simple and rapid headspace method for gas chromatographic determination of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in drinking water was developed. Acidic methanol esterification followed by a headspace technique using a capillary column gas chromatograph (GC) equipped with an electron capture detector (ECD) was applied to determine the levels of DCAA and TCAA in drinking water. The major advantages of this method are the use of acidic methanol as the derivatization agent instead of the hazardous diazomethane, and esterification is carried out in water instead of organic solvent. DCAA and TCAA methyl esters produced in the reaction were determined directly by a headspace GC/ECD method. The linear correlation coefficients at concentrations ranging from 0 to 60 microg/L were 0.992 and 0.996 for DCAA and TCAA, respectively. The relative standard deviations (RSD, %) for the determination of DCAA and TCAA in drinking water were 15 and 21.3%, respectively (n=3). The detection limits of this method were 3 and 0.5 microg/L for DCAA and TCAA, respectively, and the recovery was 68-103.2% for DCAA and TCAA.     

气囊堵水在供水管道上的应用

通过试验,分析论证了气囊在供水管道上应用的可能性,并提出了具体的建议,指出带导流孔的气囊在供水管道中凭借其在堵水作业中发挥出的独特技术优势和经济优势,具有大面积推广的实用价值。     

改进离子色谱法测定水中氟含量

离子色谱法测定水中氟离子含量,由于水中负峰的干扰,会存在较大偏差,通过在样品中添加淋洗液,可消除水的负峰,使测定结果更准确可靠。     

Improved ammonia oxidation by ozone in the presence of bromide ion during water treatment

Ammonia oxidation by ozone proceeds more rapidly in the presence of bromide ion than in its absence. Unlike the direct ozonation of ammonia, the bromide-catalyzed process is little affected by changes in pH. A reaction scheme is proposed in which bromide is oxidized to HOBr, which then brominates ammonia to produce NH₂Br. NH₂Br in turn reacts with O₃ to form NO₃⁻ and also to generate Br⁻, which thus acts as a catalyst. In accordance with the reaction model, zero-order kinetics for ammonia consumption are observed. This work points out once again the importance of Br⁻ as a water quality parameter due to its role as a catalyst in both ozonation and chlorination processes in general.     

聚氨酯固化剂中游离HDI气相色谱分析

以DB1701P毛细管柱为分析柱,十四烷为内标物,建立了一套用于聚氨酯固化剂中游离六亚甲基二异氰酸酯(HDI)检测的气相色谱条件.通过对进样温度、气化室程序升温进行选择,分别对低浓度游离HDI样品(已知样品N75)和高浓度游离HDI样品(实验室制HDI缩二脲未知样)进行分析.实验结果得到己知样品变异系数为6.48％,未知样品变异系数为1.77％;同时对合成反应过程中的高游离HDI的检测也有很好的准确度和重现性.表明该方法既适用于检测聚氨酯固化剂产品中的低浓度(0.1％～2.0％)游离HDI含量,也适用于跟踪反应过程中高浓度(30％～90％)游离HDI含量变化,对于确定合成反应的终点和检测HD1缩二脲产品性能具有重要意义.     

Simultaneous determination of alkylbenzenesulfonates and dialkyltetralinsulfonates in water by liquid chromatography

A previous method based upon Liquid Chromatography (HPLC) with fluorometric detection for determining linear alkylbenzenesulfonates (LAS) in aqueous environmental samples has been modified for extending it to the monitoring of dialkyltetralinsulfonates (DATS). DATS are reaction byproducts of LAS surfactant synthesis. 10, 100, 200, 1000 ml of respectively untreated sewage, treated one, riverwater and groundwater samples have been extracted by a 0.5-g Graphitized Carbon Black (GCB) cartridge. After sample extraction, co-extracted basic, neutral and weakly acidic compounds have been washed out by a formic acid containing solvent system. DATS and LAS have been then reextracted by passing through the cartridge a basified organic eluant mixture. After solvent removal and residue reconstitution by a suitable solvent system, the subfractionation of the analytes have been achieved by chromatographing them on a C-8 reverse-phase HPLC column. Recovery studies have shown that DATS have been quantitatively extracted by the GCB cartridge. By this procedure, the concentrations in water of DATS entering and leaving two sewage treatment plants in Rome have been monthly monitored over 1 year. With respect to LAS, the higher resistance to biodegradation of DATS has been demonstrated by comparative biodegradation tests. Analysis of a sewage-contaminated groundwater sample has shown that, although DATS are minor components in LAS formulations, the concentration of the former was even higher than that of the latter, with C₁₀ DATS being the most abundant species.     

ICS-90型离子色谱仪测定饮用水中溴酸盐含量

建立了使用ICS-90型离子色谱仪测定饮用水中溴酸盐的方法,标准曲线在2～200 μg/L的范围内有良好线性(r=0.999 6),最低检出限达到0.6 μg/L.对采用氯消毒的臭氧生物活性炭深度处理工艺出水进行了检测,加标回收为97%～109%之间,在检测精密度、最低检出限和加标回收方面均达到了相关要求.     

Validation of an automated fluorescein method for determining bromide in water

Surface, atmospheric precipitation and deionized water samples were spiked with μg l^?1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l^?1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l^?1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.     

Investigation of used synthetic lubricants by computerized gas chromatography/mass spectrometry

The chemical fractions of a used, synthetic lubricating oil for petrol engines were separated by flash chromatography on a silica gel column using variable mixtures of hexane/chloroform as eluents. The products extracted in the most polar fraction were separated by gas chromatography and then analyzed by computerized mass spectrometry. The analytical method used allowed the identification, among the various compounds, of a family of tetrahydropyran homologues with an aminic chain, phthalates, thiophene and pyridine derivatives. The presence of these structures, some of which are of toxicological interest, was also shown by infrared spectra.     

气相色谱顶空进样方法的改进

对传统的手动顶空进样和自动顶空进样进行了分析,结果表明,自动顶空进样法测定准确,并达到了简便操作,重现性好的效果,指出自动顶空进样法在气相色谱分析中可以替代传统的手动顶空进样法。     

吹扫捕集-气相色谱法同时测定水中苯系物和氯苯化合物

利用吹扫捕集法富集样品、DB—FFAP毛细管柱分离、FID检测器同时测定水中八种苯系物和四种氯代苯。通过对捕集柱吸附剂材料、毛细管色谱柱等条件进行详细研究,确定了最佳分析条件。结果表明,使用BTEXTRAP捕集柱和DB—FFAP毛细管柱可以减少干扰,有效实现了水中苯系物各组分的完全分离。当进样体积为5．0mL时,12种组分的最低检测限在0．13～0．44μg／L之间,加标回收率为95．9％～106．8％,相对标准偏差在3．9％～7．3％之间。该方法无需溶剂萃取和浓缩,缩短了分析周期,实现了一次进样多组分同时测定,具有准确度高、灵敏度高和操作简便等特点,对实际水样进行分析,获得了良好的实验效果,适用于饮用水和地表水中挥发性苯系物和氯代苯的测定。     

Self-sealing of fractures in indurated claystones measured by water and gas flow

Self-sealing of fractures in the indurated Callovo-Oxfordian (COX) and Opalinus (OPA) claystones, which are considered as host rocks for disposal of radioactive waste, was investigated on artificially fractured samples. The samples were extracted from four lithological facies relatively rich in clay mineral, carbonate and quartz, respectively. The self-sealing of fractures was measured by fracture closure, water permeability variation, gas penetration, and recovery of gas-induced pathways. Most of the fractured samples exhibited a dramatic reduction in water permeability to low levels that is close to that of intact rock, depending on their mineralogical composition, fracture intensity, confining stress, and load duration. The self-sealing capacity of the clay-rich samples is higher than that of the carbonate-rich and sandy ones. Significant effects of sample size and fracture intensity were identified. The sealed fractures become gas-tight for certain injection pressures. However, the measured gas breakthrough pressures are still lower than the confining stresses. The gas-induced pathways can recover when contacting water. These important findings imply that fractures in such indurated claystones can effectively recover to hinder water transport but allow gas release under relatively low pressures without compromising the rock integrity.