地面水中常见有机磷农药残留量气相色谱分析方法的研究

通过对色谱工作条件和水样萃取条件选择的分析，建立了有机磷农药残留量的分析方法。该方法选择涂渍４％ＳＥ－３０＋６０％ＱＦ－１的玻璃色谱柱及火焰光度检测器，有效分离定量了地面水中乐果、甲基对硫磷、乙基对硫磷三种成分峰，方法简单、快速、灵敏、重现性好。     

低温等离子体治理H2S污染的实验研究

低温等离子体技术是一种高效、快速的污染消除技术，国内外都在对其进行广泛而深入的研究。采用脉冲电晕放电等离子体对空气中的硫化氢进行降解研究，探索了、脉冲峰压、脉冲频率、气体流量以及气体初始浓度对净化效果的影响，气体浓度由气相色谱仪测定。结果表明，脉冲电晕放电可以有效消除硫化氢污染，净化率随脉冲峰压和脉冲频率的增加而提高，随气体初始浓度和流量的增加而下降，且在初始浓度360mg／m^2、流量1200mL／min、脉冲峰压30kV、脉冲频率80Hz的条件下，处理后的气体中已检测不到H2S，根据色谱检测限（0．29mg／m^3）计算出的净化率≥99．92％。采用离子色谱对产物进行了定性分析，发现H2S经放电处理后主要产物为SO2和SO3。     

热解析-固相微萃取-气相色谱法测定空气样品中挥发性有机化合物

建立了热解析-固相微萃取-气相色谱法测定空气样品中挥发性有机化合物的分析方法，并对色谱分离条件、玻璃针筒保存样品的稳定性、固相微萃取萃取纤维、萃取时间、色谱进样时间等条件进行了优化，9种挥发性有机化合物的峰面积与其质量浓度在所测范围内有较好的线性关系，相对标准偏差＜8.8%，检出限为0.05～0.75 μg/100 mL，满足实际空气样品测定需要。     

离子色谱技术中气泡的影响

离子色谱(Ion Choromatography 编写 Ic)是近年来在原经典层析基础上迅速发展起来的新技术。关于离子色谱技术国内已有不少介绍。我们在实际工作中观察到气泡影响这类仪器的正常工作。当系统引入气泡后,工作压力不稳定,分离重现性差,负峰位置改变,噪音提高,甚至使曲线出现“毛刺”,以及其它异常现象。在经典     

低温等离子体治理H2S污染的实验研究

低温等离子体技术是一种高效、快速的污染消除技术,国内外都在对其进行广泛而深入的研究.采用脉冲电晕放电等离子体对空气中的硫化氢进行降解研究,探索了、脉冲峰压、脉冲频率、气体流量以及气体初始浓度对净化效果的影响,气体浓度由气相色谱仪测定.结果表明,脉冲电晕放电可以有效消除硫化氢污染,净化率随脉冲峰压和脉冲频率的增加而提高,随气体初始浓度和流量的增加而下降,且在初始浓度360 mg/m3、流量1200 mL/min、脉冲峰压30 kV、脉冲频率80 Hz的条件下,处理后的气体中已检测不到H2S,根据色谱检测限(0.29 mg/m3)计算出的净化率≥99.92%.采用离子色谱对产物进行了定性分析,发现H2S经放电处理后主要产物为SO2和SO3.     

污水中溶解游离氨基酸和结合氨基酸测定方法研究

采用邻苯二甲醛作为柱前衍生化试剂，结合反相高效液相色谱，对污水中溶解游离氨基酸（dissolvedfreeami．nOacid，DFAA）进行定性和定量分析，探讨了污水样品有无前处理对DFAA分析的影响，并采用气相酸水解方法对污水中总溶解氨基酸（dissolvedtotalaminoacid，DTAA）进行了分析。结果表明，污水经过pH调节和N，流清洗后，可以明显去除氨和挥发性胺的干扰，色谱峰更加清晰；前处理后的水样经RP—HPLC分析，能够快速检测出14种氨基酸，各氨基酸在一定线性范围内呈现良好的线性关系，相应的线性相关系数（R^2）均大于0．99，加标回收率为92％～102％。污水处理厂进水和出水中氨基酸主要以溶解结合氨基酸（dissolvedcombinedaminoacid，DCAA）为主，与进水相比，出水中DFAA含量减少了0．22μmol／L，DTAA由5．68μmol／L降至3．08μmol／L。     

丙烯酸装置废水特征有机污染物及其荧光特性

采用吹扫捕集-气相色谱/质谱法(PT-GC/MS),液液萃取-气相色谱/质谱法(LLE-GC/MS)等方法对丙烯酸装置废水中主要特征有机污染物进行了定性、定量分析,研究了废水和各主要特征污染物的三维荧光特性。结果表明,废水中共检出有机酸、苯系物、酯、醛、醇等24种有机污染物,其中含量较大的有乙酸55.13%,丙烯酸23%,甲醛21.81%,甲苯0.03%,4-羟基-2-丁酮0.02%,丙烯酸甲酯0.01%,正丁醇0.01%。丙烯酸废水中含有3个荧光峰,区域IV内的荧光峰(λex/em=290/355 nm)主要由废水中高浓度的丙烯酸产生,区域V内的2个荧光峰(λex/em=390/495 nm,λex/em=295/480nm)由水中的腐殖质产生。丙烯酸抑制了甲苯、甲醛、乙酸等3种荧光物质对丙烯酸废水荧光强度的贡献。4种荧光物质的荧光基团影响力大小:碳碳双键+羧基苯环羰基羧基。     

鸡粪堆肥水溶性有机物转化特性研究

采用离子色谱和三维荧光光谱,分别对鸡粪堆肥不同阶段水溶性有机物(DOM)中典型小分子有机酸、磷酸和荧光有机物进行了研究。分析显示,所研究的7种酸(乙酸、琥珀酸、苹果酸、草酸、柠檬酸、酒石酸及磷酸)中,苹果酸的含量最高(1 000 mg/L),草酸的浓度最低(3 mg/L),琥珀酸和柠檬酸未检测到。随着堆肥的进行,各种酸的含量先上升而后下降,堆肥结束降至最低;堆肥过程样品所有荧光峰强度之和与COD达到显著相关(R=0.917,P0.05),类蛋白荧光峰强度与总荧光峰强度的比值不断降低,而类富里酸荧光峰强度与总荧光峰强度的比值不断上升。结果表明,堆肥过程小分子有机酸主要出现在堆肥中期;类蛋白荧光强度或类富里酸荧光强度与总荧光强度之比可以有效表征堆肥腐熟过程。     

滇池铜绿微囊藻（Microcystis aeruginosa Kueitz）毒素及其在水体中的变化

本文研究了昆明市滇池富营养化所形成水华的主要蔬菜－铜绿微囊藻（Microcystis aeruginosa Kueitz)的毒素及其在水体的变化。经研究,滇池铜绿微囊藻的提取液有一个毒峰出现,用双波长紫外分光光度计测定,发现于240nm出现一个毒峰。用色质谱联用扫描得出,其分子离子峰为1040M／Z。用小白鼠注入藻类提取液进行试验,发现其肝脏肿大,并呈紫褐色。再将肝脏匀浆提取液用高压液相色谱测定,发现有毒峰出现。在不同季节、不同地点,采取湖水,经过滤后（去除藻类和碎屑）进行测定,结果得出：在藻类生长旺季及生长繁茂的地点,水体中藻毒素的含量较高。而在藻类生长淡季及分布较少的地点,水中藻毒素含量则较少。但总的看来,经过过滤后的湖水,其中藻毒素含量少。     

改进GC/ECD法连续测定大气中的CFCs

基于气相色谱仪 (GC)和电子捕获检测器 (ECD) ,设计了一种连续测量大气中痕量氯氟烃的自动系统。系统色谱基线稳定 ,分离效果好 ,定性、定量准确可靠 ,系统高度自动化 ,长期运行无需人值守 ,自动校正数据 ,定时进行严格的质量控制 ;系统具有较高的现场测量频率 (6次 /h) ,改进的反吹 /外切设计使CFCs色谱峰不再受氧峰的干扰 ,大大延长了检测器的寿命 ,使长期连续观测成为可能。系统设计在分离效果方面优于世界气象组织 (WMO)全球大气监测网 (GAW )目前所使用的测量大气本底CFCs的方法 ,采用美国EPA认可的标气 ,外标工作曲线法测定大气CFCs的浓度 ,最低检测限可达1pL/L ,检测精密度小于 1 % ,准确度在± 3%之内 ,可用于我国本底大气观测站对CFCs的连续测定     

Voltammetric detection of trifluralin in tap water,fruit juice,and vegetable extracts in the presence of surfactants

This study describes a novel electrochemical method to determine the herbicide trifluralin in samples of water, fruit juice, and vegetable extracts in the presence of surfactants, using a glassy carbon electrode (GCE). In acidic media, trifluralin was irreversible on the glassy carbon electrode surface at ?0.5 V vs. Ag/AgCl. Surfactant presence on the electrode–solution interface modified current intensities and shifted the reduction peak potential of trifluralin. Different types of surfactant and their concentrations were investigated. The anionic surfactant significantly enhanced the peak current intensity of trifluralin. Under optimal analytical conditions, an analytical curve was obtained in the concentration range of 0.48–32.20 µM. The limits of detection and quantification were estimated at 0.031 and 0.104 µM, respectively. The method was successfully applied to quantify trifluralin in samples of water, orange and tomato juice, and green pepper, carrot, and onion extracts, with recovery rates of 97.9–102.1%. The results were in good agreement with those obtained using high-performance liquid chromatography, indicating that the proposed electrochemical method can be employed to quantify trifluralin in various types foods, with sensitivity, specificity, selectivity and reproducibility.     

The C02 Pulse Technique for Determining the Condition of Adsorbent Charcoal Beds

Activated charcoal is widely used for the purification of air. Charcoal has a large surface area (ca. 1000 square meters per gram) and acts to purify air by adsorbing gaseous pollutants on its surface. When the capacity of the surface is exhausted, the charcoal is no longer effective and must be replaced.

The carbon dioxide (CO₂) pulse technique, developed at NRL, is a non-destructive method by which one can determine the remaining capacity, or the residual life of a charcoal bed before it has become exhausted. A dose of CO₂ is injected into the air stream ahead of the charcoal bed and is eluted through the bed. The shape of the emerging CO₂ elution peak is determined by the condition of the charcoal bed. For a new, unused charcoal bed the CO₂ elution peak is considerably dispersed (flattened and broadened) due to adsorption and desorption at the charcoal surface. For a partially spent bed the elution peak is dispersed to a degree proportional to the remaining capacity of the bed. For a fully spent bed the CO₂ elution peak is little affected by passage through the bed.

The carbon dioxide puise technique has been shown to be indicative of charcoal capacity for a wide range of non-polar materials (such as hydrocarbons, alcohols, etc.), which are taken up primarily by physical adsorption. The method is essentially insensitive to relative humidity in the range between 10 and 70%. An adaptation of the method has been used for detection of leaks in a charcoal bed, such as those caused by channeling, faulty packing, etc.     

Estimation of bed shear stress and analysis of sediment resuspension in Lake Chaohu,China

Resuspended sediment is an important carrier of underwater material circulation, and bed shear stress is usually considered to be closely related to sediment resuspension. To analyze the resuspension dynamics in severely eutrophic Lake Chaohu, China, three fixed stations were set up to collect wave, current, and suspended sediment concentrate (SSC) data under windy weather, and two significant sediment resuspension events were recorded. Based on the Gaussian-shaped spectrum characteristics of waves in Lake Chaohu, the wave orbital velocity was estimated by using the wave parameter method. The selection of the general wave spectrum is important for the accurate estimation of wave orbital velocity. The results of the simple linear wave method were very similar to those of the wave parameter method with a Gaussian-shaped spectrum in Lake Chaohu. The total bed shear stress combining waves and currents during the observation period was calculated, and most of it was contributed by wind-driven waves. The bed material of Lake Chaohu has silt-enriched and weak cohesive features, and an examination of critical shear stress showed that the modified Shields curve method was still applicable to Lake Chaohu. When a sediment resuspension event occurred, the vertical gradient of SSC increased significantly, and the peak SSC value depended on the peak value of bed shear stress. As a predictor, bed shear stress only showed a good linear relationship during sediment resuspension events. At other times, the prediction of SSC using bed shear stress may be biased, especially at the time after a significant sediment resuspension event.

     

Direct electrochemical detection of glyphosate at carbon paste electrode and its determination in samples of milk,orange juice,and agricultural formulation

Abstract

This paper describes a simple, inexpensive, highly sensitive, selective, and efficient electrochemical method to determine glyphosate (GLY) in samples of milk, orange juice, and agricultural formulation. The oxidation reaction on the electrode surface was electrochemically characterised by cyclic voltammetry (CV) and square wave voltammetry (SWV). The investigation of GLY at carbon paste electrode revealed a non-reversible oxidation peak at +0.95 V versus Ag/AgCl, which was used for electrochemical detection of GLY. The operating parameters (pH, frequency, step potential, and amplitude) were optimised in relation to the peak current intensity, and a calibration curve was set up in a concentration range of 4.40?×?10^?8–2.80?×?10^?6 mol L^?1, with a detection limit of 2?×?10^?9 mol L^?1. After calibration curve was plotted, the developed procedure was applied to determine GLY in previously contaminated samples: milk and orange juice, and in a commercial formulation, obtaining recovery values between 98.31% and 103.75%. These results show that the proposed method can be used for GLY quantification in different samples with high sensitivity, specificity, stability, and reproducibility.     

Convenient dioxin measuring method using an efficient sampling train, an efficient HPLC system and a highly sensitive HRGC/LRMS with a PTV injector

An efficient sampling method for dioxins from flue gas, an efficient automatic purification and fractionation method by a new HPLC system using a sulfuric acid-silica/silica column, a Nitro column and a PGC column, and sensitive determination method by an economical HRGC/LRMS using a programmable temperature vaporization (PTV) injector were developed. It was confirmed that the dioxins could be easily collected by the proposed simple sampling train consisting of only two bottles, and the extracted sample could be purified sufficiently and separated as mono-ortho PCBs, non-ortho PCBs and PCDDs/PCDFs completely with the proposed HPLC system. The peak areas of GC/MS were increased linearly with the injection volume up to 40 microl by the PTV technique, and the sensitivity could be increased to 20 times higher than usual. This convenient measuring method can drastically reduce operation time, consumption of hazardous solvent and cost.     

Peak identification for PCDD/Fs in environmental samples at different temperature programs

A method has been developed for peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at different temperature programs. Their retention behaviours are predicted on the basis of an identification database of retention values (A, B) of gas chromatography. By the retention times of 13C labelled 2,3,7,8-substituted PCDD/F internal standards, the retentions of all PCDDs and PCDFs can be calculated. After comparison with the retentions of practical environmental samples, the predicted values have been proved to be very accurate.     

天然气引射调峰系统的噪声形成及其治理研究

采用天然气引射调峰技术，能使上海某储配站10台天然气高压球罐的储气调峰能率提高68％，大大有助于解决天然气用气高峰时的供需平衡问题，并能节约初投资人民币1亿元。但使用超音速引射器后，当球罐压力下降到某一值时会产生高频噪声，影响管束区操作环境。本文分析了噪声产生的原因．提出了合理的噪声治理方案，并进行了方案的实施。实践证明：噪声治理效果良好，降低了管束区噪声污染，达到了国家“工业企业噪声卫生标准”。     

天然气引射调峰系统的噪声形成及其治理研究

采用天然气引射调峰技术,能使上海某储配站10台天然气高压球罐的储气调峰能率提高68%,大大有助于解决天然气用气高峰时的供需平衡问题,并能节约初投资人民币1亿元.但使用超音速引射器后,当球罐压力下降到某一值时会产生高频噪声,影响管束区操作环境.本文分析了噪声产生的原因,提出了合理的噪声治理方案,并进行了方案的实施.实践证明:噪声治理效果良好,降低了管束区噪声污染,达到了国家"工业企业噪声卫生标准".     

Analysis of photochemical pollution in summer and winter using a photochemical box model in the center of Tokyo, Japan.

In order to give an effective and rapid analysis of the photochemical pollution and information for emission control strategies, a photochemical box model (PBM) was applied to one moderate summer episode, 11 July 1996, and one typical winter episode, 3 December 1996, in the center of Tokyo, Japan. The box model gave a good prediction of the photochemical pollution with minimal investment. As expected, the peak ozone in summer is higher than in winter. The NOx concentrations in winter are higher than those in summer. In summer, NO and NO2 have one peak in the morning. In winter, NO and NO2 show two peaks during the day. Three model runs including no reactions, a zero ozone boundary condition and dark reactions were conducted to understand the photochemical processes. The effects of emission reduction on the formation of the photochemical pollution in the center of Tokyo have been studied. The results show that the reduction of NMHC emission can decrease the ozone, however, the reduction of NOx emission can increase the ozone. It can be concluded that if the NOx emission are reduced, the reduction of NMHC should be more emphasized in order to decrease the ozone concentration in the center of Tokyo, Japan, especially the reduction of the NMHC from stationary source emission.     

Persistence of residues in water and sediment op a fresh‐water lake after surface application of technical chlordane

Abstract

A fresh‐water lake, free from detectable pesticide residues before this study, was treated with a commercial formulation of technical chlordane. Water and sediment samples were analysed for chlordane residues 7, 24, 52, 279. and 421 days after treatment. Residues moved rapidly from the water to the lake bottom, supporting earlier results of a laboratory study with other organochlorines.

In water, α‐ and γ‐chlordane concentrations remained proportional to total chlordane concentrations, as determined by total‐peak area measurements of gas‐liquid chronatogrammes. But in bottom sediments, α‐ and γ‐chlordane were more persistent than other constituents of technical chlordane, supporting recent evidence that quantification of technical chlordane residues on the basis of γ‐chlordane quantification only (or that of a‐ and γ‐chlordane only), can lead to incorrect results and that this method, although simple and fast, should no longer be recommended.