微库仑法测定高纯铁中痕量硫

微库仑法测定高纯铁中的痕量硫具有灵敏度高、简便等特点。本文在资料[理化检验,(4),24(1982)]的基础上进行了改进。方法原理:硫在铁内以硫化铁和硫化锰形式存在,以盐酸溶解样品时,发生如下反应:     

微库仑法测定纯镍、纯钴及镍铝合金中的痕量硫

本文提出了用微库仑法测定纯镍、钴及镍铝合金中痕量硫,采用盐酸和过氧化氢溶解金属镍及镍铝合金,同时将硫离子氧化为硫酸根。在氢碘酸一次磷酸介质中,硫酸根被还原为硫化氢。逸出的硫化氢由氮气载入电解池中,库仑滴定所需电量由电子积分器显示,试样中含硫量由校正曲线给出。对于测定0.0004％硫的标准偏差是4×10~(-5)％。     

两个多核四硫代富瓦烯类衍生物的合成和电化学行为

合成了２个含３个四硫代富瓦烯单元的化合物，给出了它们的核磁共振氢谱、质谱、紫外吸收光谱及元素分析数据。用循环伏安法测定了它们的氧化还原电位，并将其与仅含１个或２个四硫代富瓦烯单元的化合物的氧化还原电位比较。发现随着分子内共轭程度的增加，分子内的库仑斥力也随之降低。     

紫外荧光光谱法测定焦炉气中的痕量总硫

采用紫外荧光光谱法测定焦炉气制取液化天然气的原料气中痕量总硫,考察了样品引入速率、进样量、气体流量、燃烧温度、取样方式和进样方式等条件对分析结果的影响。总硫检出限为15μL·m-3,测定结果与气相色谱法和微库仑法的结果相吻合,测定值的相对标准偏差(n=7)小于10%。     

库仑滴定法测定铁矿石中硫

铁矿中硫的测定国家标准采用硫酸钡重量法[1]、燃烧碘量法[2]。近年来,库仑定硫的分析方法在许多方面得到广泛应用,并实现了分析的自动化。煤中全硫分析[3],库仑滴定法已作为国标分析方法之一。以库仑滴定为基础的各种智能定硫仪的应用,给冶金生产中各阶段不同产品中硫的控制分析应用带来了宽广的前景,越来越显示其生命力。本文使用KZDL 3B型快速智能定硫仪,试验了不同含硫量的铁矿、烧结矿、球团矿的标准试样,就库仑定硫仪的载气、流量、催化剂及其用量等对分析结果的影响作了探索和讨论。1　试验部分1.1　主要仪器与试剂KZDL 3B快…     

电量法测定轻质石油产品中氯含量

轻质石油产品中痕量氯的测定有灯法、联苯钠法、氨钠法以及微库仑法等。但这些方法有的操作繁琐费时,有的消耗大量试剂造成空白偏高,有的条件过于苛刻,操作困难。本文用自制的WK-1型微库仑滴定仪,探讨了微库仑滴定法测定氯的影响因素,并对测定轻质石油产品中0.2～500ppm氯含量的操作条件进行了讨论。     

微库仑法测定石油及其产品中总氮

微库仑法测定石油产品中总氮,已得到广泛应用,有些国家已列为标准方法.为了用同一装置和方法测定性质广泛变化的各种石油及产品中的氮含量,我们又进行了原油、渣油中总氮测定的研究.     

库仑法测定CODcr的改进

CODCr是港口污水达标排放的一项重要水质指标。库仑法测定CODCr与重铬酸钾经典滴定法相比，具有操作快，试剂省，测量范围大，无需每天标定FeSO4标准溶液等,优点，但库仑法测定CODCr还存在重现性，稳定性不够理想的问题。     

微库仑法测定石油硫含量

建立了测定石油中硫含量的微库仑法。用硫标准样品对库仑仪的最佳工作参数进行试验和调整,结果表明:裂解段温度为1 000℃,空气流量为1 L/min,裂解段停留时间至少2.5 min时测定结果较为理想。低硫含量、中硫含量、高硫含量油品的取样量分别为10~20 mg,9.5~11.5 mg,5.5 mg左右。该方法测量结果的相对标准偏差小于3%(n=6),两种硫标准样品回收率分别为100.2%,101.9%。该法适用于石油中硫含量的测定。     

硅、二氧化硅中微量硫的库仑滴定

微量硫的存在直接影响硅及二氧化硅制品的性能。我们利用库仑滴定的方法,自己组装仪器,设计制造吸收室,解决了硅及二氧化硅中微量硫的测定。方法简便、快速,灵敏度为0.5 ppm,空白1-5ppm,再现性±7.7％。实验装置库仑定硫装置如图1所示。其简要流程示于图2。     

A spectrophotometric method for the determination of nitrite

Nitrite reacts with dichromate quantitatively under suitable conditions of temperature and acid concentration. A linear relationship was found to exist between nitrite concentration and the absorbance at 580 nm of the chromium (III) species produced. This was used to determine the nitrite. The influence of a number of ions on the determination of nitrite was investigated; up to 100-fold excess nitrate has no influence on the determination of nitrite.     

Catalytic adsorptive stripping voltammetry determination of ultra trace amount of tungsten using factorial design for optimization

A highly sensitive procedure is presented for the determination of ultra-trace concentration of tungsten by catalytic adsorptive stripping voltammetry. The method is based on adsorptive accumulation of the tungsten-pyrocatechol violet complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species by voltammetric scan using differential pulse modulation. The reduction current is enhanced catalytically by chlorate. The influence of variables was completely studied by factorial design analysis. Optimum analytical conditions for the determination of tungsten were established. Tungsten can be determined in the range 0.06–12.0 ng/mL with a limit of detection of 0.02 ng/mL. The influence of potentially interfering ions on the determination of tungsten was studied. The procedure was applied to the determination of tungsten in one sandwich polyoxometalate and some synthetic samples similar to alloy compounds with satisfactory results.     

Determination of Metal Traces in Polypropylene by Gas Chromatography

A procedure was developed for determination of metal traces in polypropylene on chromatographic sorbents and phases of various polarities. The thermal stability of volatile aluminum, chromium, and gallium acetylacetonates under the conditions of gas chromatography was studied. The influence exerted on the determination process by the column material, temperature, and polarity of phases was examined.     

氢化物发生电热原子吸收法测定食品中微量锑铋

本文将电热氢化物原子吸收光谱技术应用于食品中微量锑铋测定,检出限可达ppb级。探讨了被测元素价态、预还原条件等因素对测定灵敏度的影响,并应用于罐头食品中微量锑铋分析。     

测定甲醇合成气中微量硫化物的注意事项

根据微量硫分析仪测定人工煤气中微量硫化物的原理和仪器本身的特点，分析了用该法测定甲醇合成气中微量硫化物时，温度、气体配比等因素对测定结果的影响，指出了测定时应注意的事项。     

Preconcentration of trace amounts of uranium in water samples on octadecyl silica membrane disks modified by bis(2-ethylhexyl) hydrogen phosphate and its determination by alpha-spectrometry without electrodeposition

A simple and reliable method for the selective extraction and determination of uranium in water using octadecyl-bonded silica membrane disks modified with bis (2-ethylhexyl) hydrogen phosphate and alpha-spectrometry is described. Extraction efficiency and influence of sample matrix, optimum amount of extractant, type and minimum amount of organic eluent and flow rates were evaluated. The limit of detection of the proposed method is 40 ng per 1000 ml. The influence of potential interfering cations in water samples on the recovery of U(VI) was investigated. The method was successfully applied to the extraction and determination of uranium in natural water.     

复混肥料中氯离子含量测量不确定度的评定

对硫氰酸铵滴定法测定复混肥料中氯离子含量的测量不确定度进行了评定。分析了测量重复性、滴定管、标准溶液浓度等因素对氯离子含量测量不确定度的影响。计算得复混肥料中氯离子含量测定结果的扩展不确定度为0．049％。     

微波消解分光光度法测定污水中的总磷

建立微波消解分光光度法测定污水中总磷的方法。采用微波消解法消解污水．讨论了消解时间和压力对消解效果的影响。测定总磷的线性范围为0～0．4mg/L。用该法测定总磷环境标准样品中的总磷,测定结果与标准值基本一致,测定结果的相对标准偏差为1．65％(n=5)。     

Photochemical derivatization and fluorimetric determination of reserpine in a flow-injection assembly

The fluorimetric flow-injection determination of reserpine was achieved with the drug being derivatized on-line by photoreaction. PTFE tubing was helically coiled around a germicide lamp located between the injection valve and detector. Two analytical procedures are proposed using either dilute acetic acid or pure methanol as the carrier stream. The influence of foreign compounds was studied and the method was applied to the determination of reserpine in pharmaceutical formulations.     

Solid phase extraction and graphite furnace atomic absorption spectrometric determination of ultra trace amounts of bismuth in water samples

A simple and reliable method for the selective extraction and determination of bismuth in water as well as alloy samples using octadecyl bonded silica cartridge modified with cyanex 301 and graphite furnace atomic absorption spectrometry is described. Extraction efficiency and influence of sample matrix, optimum amount of extraction ligand, type and least amount of proper eluent and flow rates were evaluated. The limit of detection of the proposed method is 0.01 ng ml(-1). The influence of potential interfering cations in water samples on the recovery of bismuth was investigated. The method was successfully applied to the extraction and determination of bismuth in natural water and alloy samples.