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1.
纪雷  刘钢  王岩  崔鹤 《分析化学》2002,30(2):247-247
1引言碳(碳酸盐)的测定曾做过广泛研究,其中,非水库仑滴定测碳因其滴定效率高,稳定性好被列入ASTMD-513-82;该方法推荐使用美国库仑公司的专利仪器及电解液,其关键技术是非水电解液。本文对该方法的电解液进行了组分选择及优化,建立起完整的测定装置,取得了较好的结果;可作为测定金属含碳量、水体中溶解无机碳的首选方法,广泛应用于冶金、环保等领域。2实验部分2.1仪器与试剂KLT-1型库仑仪(江苏电分析仪器厂);PHS-2型酸度毫伏计(上海雷磁仪器厂)。试剂:二甲亚砜、乙醇胺、四乙墓滨化胺为分析纯;…  相似文献   

2.
对运用卡尔菲休滴定仪库仑法测定液体石油产品中微量水的简单原理、分析方法的建立与分析流程进行了论述.实验结果表明,该方法测定结果的相对标准偏差为0.66%~1.30%(n=8),用该方法测定3种标准物质,其相对误差不大于2%.该方法分析快速、简便,适用于含有醇类、无机含氧弱酸特殊样品的测定.  相似文献   

3.
许多碱性药物的测定通常是采用非水中和滴定法,但对于含量少(毫克级)的药物用上述方法不易准确测定,为此我们尝试用非水库仑法测定。其理论依据是法拉第电解定律。只要能准确地测定电解电流和时间,物质的量就能准确地测定。与水介质不同,在水介质中指示电极使用双铂片电极可得到很明显的终点响应,而在非水介质中结果不满意。因此,我们采用通小电流极化的两个醌氢醌铂片电极作为指示电极[1]的库仑滴定法来测定碱性药物安定片。其结果符合药典法的要求。  相似文献   

4.
测定金属中碳的方法一般是将金属试样放在氧气流中燃烧,其中的碳化物及游离碳全部转化为二氧化碳,然后用重量法、气体容量法、氢氧化钡滴定法、非水滴定法、电导法、库仑法等方法进行测定。本文用库仑法测定铌、钽中0.002—0.1%碳,对有关条件进行了试验,选取  相似文献   

5.
用苯甲酸中和叔丁醇钾中的微量杂质氢氧化钾,使二者反应生成水,再利用卡尔·费休库仑滴定法测定其水的含量,从而计算出叔丁醇钾中游离碱的含量。研究了样品处理方法、测定过程的影响因素以及测定条件。测定结果表明,该法操作简便,结果准确、可靠,适用于该类样品的测定。  相似文献   

6.
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。  相似文献   

7.
用苯甲酸中和叔丁醇钾中的微量杂质氢氧化钾,使二者反应生成水,再利用卡尔·费休库仑滴定法测定其水的含量,从而计算出叔丁醇钾中游离碱的含量.研究了样品处理方法、测定过程的影响因素以及测定条件.测定结果表明,该法操作简便,结果准确、可靠,适用于该类样品的测定.  相似文献   

8.
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。  相似文献   

9.
本文首次报道用催化动力学和库仑分析相结合的方法测定抗癌药物乐疾宁中的主要成份6-巯基嘌呤(6-MP)。此法基于测定与催化剂(或称诱导剂)6-MP浓度成正比的库仑池反应诱导期(从接通电源到指示电流突然增大到指定值的毫库仑数),从而求出催化剂6-MP的量。本法具有库仑分析法与催化动力学分析法的优点即准确、灵敏、快迅和简便。方法线性范围为1.47×10~(-7)~5.29×10~(-6)mol/L。应用于药物乐疾宁中6-MP的测定,回收率为95%~103%,结果满意。  相似文献   

10.
为了减少高毒试剂苯的使用,缩短脱脂时间,减少酸性洗涤过程中半纤维素水解不完全对测定结果的干扰,采用乙醇–乙醚混合液超声对烟草样品进行脱脂处理,用2 mol/L盐酸洗涤后测定酸性洗涤纤维,对YC/T347–2010标准方法进行优化。方法优化后减少了试剂毒害,脱脂时间由8.5 h缩短为1.5 h;测定酸性洗涤纤维中半纤维素水解更完全,洗涤剂法计算的半纤维素含量与水解法测定半纤维素含量的结果基本一致。改进后方法的回收率为98.38%~99.97%,测定结果的相对标准偏差为0.25%~1.88%(n=6)。该方法可以代替苯–醇–醚加热回流脱脂法测定烟草及烟草制品中中性洗涤纤维和酸性洗涤纤维。  相似文献   

11.
Budevsky O 《Talanta》1989,36(12):1209-1216
A new approach for selection of a suitable solvent system as a medium for non-aqueous acid—base titration is proposed. The essence of the approach is the development of a new criterion called “effectivity”. The latter is based on consequences of the Brønsted and Izmailov acid—base theories and represents a quantitative measure for improving or worsening the titration conditions of acids and bases in non-aqueous solvents as compared with water. The “effectivity” E is given by the relation E = ΔpKs - ΔpKs where ΔpKs is the difference between the logarithmic values of the autoprotolysis constants of water and the solvent in question, and ΔpK is the so-called medium effect. The latter is a constant value which shows that acids and bases with the same charge alter their strength to the same extent when transferred from water into a non-aqueous solvent. The medium effect is calculated by statistical treatment of a great number of acid—base constants determined experimentally both in water and the non-aqueous solvent in question. The effectivity of the solvents most often used in non-aqueous acid—base titrimetry, determined by this approach, shows that in many cases these solvents offer significant advantages over water, but drawbacks are also observed. Some limitations of the approach are discussed. Special attention is paid to dimethylsulphoxide and its mixtures with water, which prove to be highly effective media for the acid—base titration of many substances.  相似文献   

12.
The biguanide concentration of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was measured by non-aqueous titration with HClO4, argentometric titration, the Kjeldhal method, and colloidal titration. The summation value of non-aqueous titration and argentometric titration corresponded to two titrable nitrogens in five nitrogens per one unit of PHMB-HCl, and consisted with the result of the Kjeldhal method to the five nitrogens. The colloidal titration of PHMB-HCl at pH 2.05 was equal to that with the two nitrogens. The relative standard deviations of non-aqueous titration, argentometric titration, the Kjeldhal method, and colloidal titration were 0.50% for 8 runs, 0.13% for 7 runs, 3.61% for 6 runs, and 0.69% for 6 runs, respectively.  相似文献   

13.
Wahbi AA  Onsy S 《Talanta》1978,25(11-12):716-717
Direct and indirect non-aqueous titrimetric methods for the determination of mebendazole are presented. These methods are reproducible, with relative standard deviations of 0.3%. Mebendazole in tablets (100 mg per tablet) has also been determined spectrophotometrically with use of perchloric acid as solvent. The relative standard deviation was 1.4%. The methods are easy to automate for routine analysis.  相似文献   

14.
对有机物燃烧热的测定方法进行了改进。改变点火丝的安装方法,采用高性能量热计,改变氧弹内氧气的压力及燃烧样品的用量,确定了新的测定方法。采用新的测定方法测定萘的燃烧热,测定结果的相对误差为0.05%,相对标准偏差为0.077%。  相似文献   

15.
利用气相色谱手性分析,对醇腈酶促不对称合成手性氰醇中的pH值、温度、底物浓度和水含量对酶反应速度和非酶反应速度的影响作了研究。结果表明,上述因素对酶反应和非酶反应速度均有显著影响。在水含量较低的非水相酶反应体系中,pH值在4.0以下或反应温度为0-5℃时,非酶反应受到较大程度的抑制,而酶反应仍具有相对较快的反应速度,故可获得高光学纯度的产物。  相似文献   

16.
Plaques of branched polyethylene stabilized with 0.1 wt.% 4,4′-thiobis(6-tert-butyl-3-methylphenol) [Santonox® R] were aged at different temperatures between 75 and 95 °C in anaerobic (nitrogen or water) and aerobic (air or water saturated with air) media. Antioxidant concentration profiles were obtained by oxidation induction time (OIT) measurements using differential scanning calorimetry. Results obtained by high performance liquid chromatography of extracts confirmed that the gradual decrease in OIT with increasing ageing time was due to migration of antioxidant to the surrounding medium. The antioxidant concentration profiles along the plaque thickness direction were flat in the plaques aged in the non-aqueous media indicating that the migration of antioxidant to the surrounding medium was controlled by the low evaporation rate at the material boundary. Crystals of antioxidant were detected by optical microscopy on the samples exposed to nitrogen. The similarity of the antioxidant concentration profiles obtained after ageing in nitrogen and in air suggested that the fraction of the antioxidant oxidized is negligible in comparison with the loss of antioxidant by migration to the surrounding media. The antioxidant concentration profiles along the plaque thickness direction obtained after ageing in water were less flat, suggesting faster dissolution in the water phase than evaporation in the case of non-aqueous ageing. The antioxidant diffusivity could be determined from the aqueous experiments and was in reasonable agreement with data reported by Moisan. For the samples exposed to water, the loss of antioxidant was faster from the samples exposed to water saturated with air. This difference is attributed to a faster degradation of the antioxidant in the oxygen-containing water phase increasing the mass transport from the polymer phase boundary to the water phase.  相似文献   

17.
Details of the standardization of the reference electrode Hg/HgCl2(s) versus the SHE by a potentiometric method using two acids (viz., perchloric and 2,5-dichlorobenzene-sulfonic acids) in 80 mass % propylene carbonate (PC) + p-xylene (PX), are presented. Using this reference electrode, the standard electrode potential of the quinhydrone electrode was determined in this medium. The reference electrode potential and the standard electrode potential of the quinhydrone electrode were found to be (0.277±0.003) and (0.760±0.003) V versus SHE in 80 mass % PC + PX at 25 °C, respectively. The voltammetric behavior of the quinhydrone system in this medium was investigated at a micro platinum electrode against a non-aqueous double-junction Ag/AgCl reference electrode. The standard electrode potential of the quinhydrone system was also calculated using voltammetric and chronocoulometric data that is comparable with the value obtained by potentiometry.  相似文献   

18.
The solubility and the protolytic constants of 1-(2-pyridylazo)-2-naphthol (PAN) have been accurately determined at temperatures between 20.0 and 30.0°C in ethanol–water solutions with ethanol concentrations ranging from 10.0% to 95.0% (v/v). The measurement of the protolytic constants is based on the spectrophotometric determination of the concentrations of the corresponding conjugate acid–base pairs in ethanol–water solutions containing PAN and hydrochloric acid or sodium hydroxide. The traditionally used pH measurements in such studies in non-aqueous solutions are thus avoided. The solubility and the protolytic constants of PAN in pure water have been calculated by extrapolating the ethanol–water results to pure water where PAN is practically insoluble. The determination of the thermodynamic data mentioned above is necessary for elucidating the interactions of PAN with various metal ions in solutions and in cation-exchange membranes (e.g., Nafion®) used as PAN-based optodes.  相似文献   

19.
孙进  宋洪涛  张天虹  王卓  何仲贵 《色谱》2006,24(2):164-167
建立了快速、灵敏和准确的柱前衍生化高效液相色谱测定固定剂量复方抗结核制剂中盐酸乙胺丁醇的含量和溶出度的方法。在无水环境下,盐酸乙胺丁醇与苯乙基异氰酸酯发生柱前衍生化反应的最佳反应的物质的量比为1∶6,检测波长为215 nm。该法成功地用于由4种药物组成的复方抗结核制剂中盐酸乙胺丁醇的含量和溶出度的测定。  相似文献   

20.
It is demonstrated that the addition of 5% of water to the non-aqueous solvent for the titrimetric determination of carbon in steel improves the performance of the titration. Modifications to the procedure are proposed which allow the normal titrant, tetra-n-butylammonium hydroxide dissolved in benzene-methanol, to be replaced by an aqueous solution of potassium hydroxide. The proposed procedure has been applied to the analysis of a wide range of standard steel samples.  相似文献   

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