卡尔费休库仑法测定微量水的装置改进

针对工业生产中聚合级原料气体中微量水检测中的问题,对卡尔费休库仑装置进行了改进。利用改进后的装置测定聚合级异丁烯、氯甲烷中微量水,平均相对标准偏差为5.8％,回收率为92.4％～103.7％;测定六氟化硫气体中痕量水,其测定结果与五氧化二磷电解法基本相符。通过潮湿环境实验,证明了改进后的装置适宜在潮湿环境下测定气体中的微量水,操作简便,测定结果可靠。     

微量水对α-丙酸类化合物对映体正相色谱分离选择性的影响

采用正相液相色谱系统,通过向流动相中添加微量水,建立了8种手性α-丙酸类污染物或降解产物对映体的拆分方法,并探讨了微量水的影响机制。采用的色谱柱为Chiralcel OJ-H column (25 cm×4.6 mm, 5 μm),以正己烷-异丙醇-乙酸为流动相,流速为0.8 mL/min。结果表明,微量水的添加能显著影响α-丙酸类污染物及其降解产物对映体的分离效果;微量水可通过竞争待测组分在手性固定相上的作用位点,或者诱导流动相pH的变化来改变弱酸类化合物的解离,影响α-丙酸类化合物的手性拆分;弱酸类化合物比羧酸酯和酰胺类等中性化合物对微量水的响应更敏感,其中部分化合物的拆分机制发生了改变。     

靛蓝-F-组合探针光度法检测非质子有机溶剂中的微量水

以靛蓝-F^-为组合探针,建立了非质子有机溶剂(DMSO、THF、DMF、二恶烷、乙腈)中微量水的比色检测新方法。结果表明,F^-加入靛蓝溶液后体系的颜色由蓝色变为黄绿色,进一步加入微量水之后,体系从黄绿色又变回蓝色,因而可作为一种变色探针实现对有机溶剂中微量水的裸眼识别检测。体系具有较高灵敏度,对DMSO、THF、DMF、二恶烷及乙腈中微量水的检测限分别为0.022%、0.043%、0.016%、0.34% 和0.015%。该方法实验操作简便、快速、灵敏、安全。实验结果表明,靛蓝与F^-的结合比为1:2。利用核磁滴定方法对机理进行了探讨。     

吸附伏安法测定表面活性剂的临界胶束浓度

以易溶于有机溶剂，微溶于水的氧化－还原指示剂中性红为探针，用吸附伏安法测定了阴离子表面活性剂的临界胶束浓度。测量的基本原理是：存在于表面活性剂溶液中的微量中性红在悬汞电极上的吸附伏安峰电流对表面活性剂浓度的曲线在临界胶束浓度处有一拐点。     

超纯气体中微量水的气相色谱分析

超纯气体制备和用超纯气体做保护气的许多工业部门,对气体中微量水是需要经常分析的。目前常用的大都是露点法,其缺点是仪器只能专用;而用高灵敏度热导检测器气相色谱仪,不但可方便地测出超纯气体中的微量水,而且还可以测定超纯气体中的微量气体杂质及作其它有机物分析之用。气相色谱仪操作简单,定量也较方便准确。     

四氧化二氮微量水标准物质的研制

以四氧化二氮为原料,经预脱水、深度脱水和精馏等处理工艺制备了7种浓度的四氧化二氮微量水标准物质.两家实验室采用核磁共振方法对标准物质中的微量水含量进行定值分析.用方差统计方法对定值结果进行数据处理和不确定度评定.     

用新型高分子多孔小球分析水的研究

本文提出一种新型高分子多孔小球固定相,它具有比商品的尤其是苯乙烯系高分子多孔小球更加优越的色谱性能,特别适合于各种有机物和无机气体中微量至常量水的分析,同时还是测定大量水中微量有机物的一种较为理想的固定相。     

用氢化铝锂-气相色谱法分析液体中的微量水

在石油化工产品和有机溶剂的使用中,常常需要分析其中的水含量。文献报导了很多微量水的分析方法,使用较多的有卡尔一费休库伦法,红外光谱法,气相色谱法等,各有特点,并均在不断改进中。气相色谱法分析微量水研究的较多。有两种方式,一为直接进样法,一为转化进样法。直接进样法是利用色谱柱把水和     

一种在非水介质中检测有机化合物微量水的电化学传感器

制备了聚二-(1,10-邻菲啰啉)(1,10-邻菲啰啉-5,6-二酮)合钌修饰玻碳电极,研究了在非水介质中与水反应后的电极反应,成功构建了一种检测微量水的电化学传感器,建立了在非水介质中检测有机物中微量水的电化学分析法.在含有0.05 mol/L六氟磷酸四丁基胺的乙腈溶液中,采用差分脉冲伏安法,在电位-0.12 V处测得的阳极峰电流与水含量在0.02％～5.66％范围内成正比,检出限为0.005％(S/N=3).将传感器分别应用于乙腈、丙酮、93号汽油、柴油4种有机物中微量水的测定,相对标准偏差小于3.6％,加标回收率为94.1％ ～ 105.0％,测定结果与卡尔费休法相符.     

7259型氯离子计的研制

为了防止不锈钢锅炉产生氯离子应力腐蚀,要求对锅炉水中微量的氯离子作连续自动的监测。我们研制了适合该用途的全套仪表——7259型氯离子计。该仪器的检测下限为20ppb,表头直读范围为0.1～10ppm。测量精度为±5％。该仪表设计时已考虑到防潮、防震、防冲击、防腐蚀等工业现场使用条件。既适用于现场监测,又适用于实验室。操作简单,使用方便,测量准确。全套仪表由探头,氯离子计,动水台架和电磁搅拌器组成。     

卡尔-费休库仑法水分测定仪的改进

对GB7600—1987推荐的YS-2型微库仑仪进行了功能改进，设计出DT-305型全自动微量水分测定仪，增加了大电流冲击电解液中的残余水分、掉电存储参数、通讯、程序升级等新功能，仪器改进后提高了测量的准确度和实验的方便性。     

Dispersed Molecular Aggregates

Colloidal dispersions of tungstic acid (H(2)WO(4)) have been prepared in water/(TX-100+alkanol)/n-heptane water-in-oil microemulsion media by reacting Na(2)WO(4) with HCl. The effects of alkanol chain length, TX-100/alkanol mass ratio, temperature, and dilution at different [water]/[TX-100] mole ratios (omega) have been studied by the dynamic light scattering technique. The formation of H(2)WO(4) in the microwater pool has been established by FT-IR measurements. The particle sizes and shapes in microemulsion media and in isolated states have been measured by TEM and SEM techniques. The enthalpy of formation of H(2)WO(4) in the water pool of the microemulsions has also been determined microcalorimetrically. Copyright 2001 Academic Press.     

Contributions to the ethyl acetate application in residue analysis

Summary For the determination of pesticide residues 10 fruit and vegetable samples and 2 wheat samples with unknown spray history were extracted by the micro on-line extraction technique using the binary solvent system water + ethyl acetate as the extracting agent. The results of this proposed micro extraction were compared with already tested methods and it was found that the micro ethyl acetate method was equally effective. The reduction of solvents and chemical waste by miniaturization of analytical procedures is an important step for environmental protection.     

Field determination of trace iron in fresh water samples by visual and spectrophotometric methods.

Sensitive visual and micro spectrophotometric methods have been developed for field determination of trace iron in fresh water samples. For the visual method, a water sample (0.45-microm filtrate acidified to 0.1 M HCl) was placed in a glass vial and mixed with a reagent solution containing 1,10-phenanthroline, sodium thiocyanate and 0.1 M HCl. Iron was extracted as pink ferroin thiocyanate with 1 ml of 4-methy-2-pentanone. The sample up to 20 ml was added step-by-step, until the color of the extract was detected visually. Without any special instrument or color standard, iron down to 0.001 mg 1(-1) (0.025 microg) in a sample can be determined with an error of 20% in the field. For the micro spectrophotometric method, the extract for 20 ml of sample was separated by capillary suction in a column (micro pipette chip) with acrylic fibers. A part of the extract was pushed out into a micro cell for the absorbance measurement at 525 nm. The column was re-usable after washing with ethanol. This method had a detection limit of 0.001 mg 1(-1) and allowed determinations within an error of 5%. The proposed methods were applied to deionized-, tap-, river-, lake- and reservoir-water samples.     

Simultaneous determination of triclosan,triclocarban, and transformation products of triclocarban in aqueous samples using solid‐phase micro‐extraction‐HPLC‐MS/MS

The presence of triclosan and triclocarban, two endocrine‐disrupting chemicals and antimicrobial agents, and transformation products of triclocarban, 1,3‐di(phenyl)urea, 1,3‐bis(4‐chlorophenyl)urea and 1,3‐bis(3,4‐dichlorophenyl)urea, in tap water, treated household drinking water, bottled water, and river water samples were investigated using solid‐phase micro‐extraction coupled with‐HPLC‐MS/MS, a rapid, green, and sensitive method. Factors influencing the quantity of the analytes extracted onto the solid‐phase micro‐extraction fiber, such as addition of salt, sample pH, extraction time, desorption time, and sample volume, were optimized using solid‐phase micro‐extraction‐HPLC‐MS/MS. The results showed that the method gave satisfactory sensitivities and precisions for analyzing sub‐part‐per‐trillion levels of triclosan, triclocarban, and transformation products of triclocarban in samples collected locally. The recoveries of analytes ranged from 97 to 107% for deionized water samples, and 99 to 110% for river water samples, and limits of detection were in the range of 0.32–3.44 and 0.38–4.67 ng/L for deionized water and river water samples, respectively. On average, the daily consumption of triclosan and triclocarban by an adult by consuming 2 liters of different types of drinking water were estimated to be in the range of 6.13–425 ng/day as a result of the concentrations of triclosan and triclocarban measured in this study.     

In-tube solid-phase microextraction-capillary liquid chromatography as a solution for the screening analysis of organophosphorus pesticides in untreated environmental water samples

This paper describes a method for the selective screening of organophosphorus pesticides in water. In-tube solid-phase microextraction (SPME) in an open capillary column coupled to capillary liquid chromatography (LC) with UV detection has been used to effect preconcentration, separation and detection of the analytes in the same assembly. For in-tube SPME two capillary columns of the same length and different internal diameters and coating thicknesses have been tested and compared, a 30 cm x 0.25 mm I.D., 0.25 micro m thickness coating column, and a 30 cm x 0.1 mm I.D., 0.1 micro m of coating thickness column. In both columns the coating was 95% dimethylpolysiloxane (PDMS)-5% diphenylpolysiloxane. The proposed methodology provided limits of detections (LODs) for the tested organophosphorus pesticides in the 0.1-10 micro g/L range, whereas the direct injection of the samples onto the capillary LC system provided LODs in the 50-1000 micro g/L range. The sensitivity of the proposed in-tube SPME-capillary LC method is adequate to monitorize the analyte levels in drinking water. Several triazines, polycyclic aromatic hydrocarbons (PAHs), nonylphenol, organochloride pesticides or polybrominated diphenyl ethers (PBDEs) have been evaluated as possible interferents. The reliability of the described method is demonstrated by analysing different real water samples.     

Preparation,properties, and application of polypropylene micro/nanofiber membranes

Nanofiber membranes have huge potential applications in many areas due to their unique properties. However, the thermoplastic micro/nanofiber membranes were rarely reported. In this paper, polypropylene (PP) nanofibers were prepared by melt extrusion of immiscible blends of PP, cellulose acetate butyrate (CAB), and subsequent removal of the CAB matrix. The wet‐laid application was used to make PP nanofiber membranes and PP‐g‐MAH/nonwoven micro/nanofiber membrane. The properties of membranes including morphology, apparent density, porosity, contact‐angle, pore size distribution, and water flux were characterized. The results showed that the consequent membranes were provided with optimistic porosity and pore size distribution. Moreover, they were all with high pure water fluxes, which were superior to that of PP microporous membrane. They performed an excellent separation performance of TiO₂ suspension and dyeing wastewater. The work revealed this method could be an efficient one to make thermoplastic polymer micro/nanofiber membranes, and they would have a brilliant potential application for water treatment. Copyright © 2010 John Wiley & Sons, Ltd.     

A collaborative study for intermethod comparison

A collaborative study for the determination of vinclozolin and captan in lettuce and pears was conducted in the author's laboratory. In two 3-day courses the participants of twelve laboratories analysed the samples by the micro on-line method and two macro methods for intermethod comparison. The pesticides were determined by GC-ECD after clean-up on silica gel deactivated by 10% water. The results of the micro method are well comparable with those of the macro methods. Therefore, the macro extraction methods can be substituted by the micro on-line method.     

Low EOF rate measurement based on constant effective mobility in microchip CE

A new method for quickly determining low EOF rates (micro(EOF)) in microchip CE is described. The measurement is based on the notion that the effective mobility (micro(eff)) of an analyte is a constant in a certain BGE. The micro(eff) of an analyte is determined in a reference fast-electroosmosis microchip, and the apparent mobility (micro(app)) of the analyte can be determined in the microchip with unknown low electroosmosis, and then micro(EOF) in the low-electroosmosis microchip can be calculated according to the equation mu(EOF) = micro(app) - micro(eff). By an indirect method or other conventional methods, micro(eff) can be easily measured in the reference microchip. The proposed method is particularly useful for low-electroosmosis measurements in wall-modified microchannels.