酸性镀锌溶液中氯化锌的分析方法

制定了测定酸性镀锌溶液中氯化锌的新方法。在pH=5.4的条件下用抗坏血酸掩蔽镀液中的亚铁离子,用氟化铵掩蔽铝离子,用硫脲掩蔽铜离子,以二甲酚橙作指示剂,用EDTA标准滴定溶液滴定锌。实验表明,本法的相对平均偏差为0.09%,回收率为99.24%,精密度和回收率都较高。     

硝酸银容量法快速测定水质中氰化物

经蒸馏得到的碱性馏出液,用硝酸银标准溶液滴定。本方法重现性好,回收率满意,采用两种方法检验结果无显著性差异,检出限为0·0026mg/l,本法简便、快速、准确,能满足水质卫生标准要求,可适用于基层单位对水质中氰化物的测定,具有一定的实用价值。     

容量滴定法测定味精中谷氨酸钠含量的研究

采用标准试剂合成味精试样,对GB/T5009.43-1996酸度计法测定味精中谷氨酸钠含量进行了研究。结果表明,其滴定终点控制在pH9.40～9.60或9.80～10.00时,测定结果与旋光法及理论值有明显差异;当滴定终点控制在pH9.67时,与后二者结果一致,最佳终点pH值为9.67。对味精中其它添加物呈味核苷酸钠、蔗糖及淀粉的干扰情况也作了进一步实验摸索。     

正极材料钴酸锂中钴含量的测定

用高氯酸溶解LiCoO2试样,用抗坏血酸为掩蔽剂,加入六次甲基四胺缓冲溶液,在pH=6．5的酸性条件下,用孔雀石绿和二甲酚橙作为指示剂,采用乙二胺四乙酸（EDTA）络合滴定容量法,使EDTA与Co^2＋形成稳定的络合物,测定锂离子蓄电池正极材料钴酸锂中的钴含量。讨论了酸溶剂、温度、共存离子等对测定结果的影响。结果表明该方法操作简单,终点容易判断。该方法的相对标准偏差小于0．1％,回收率在99．5％～100．5％之间。     

酸性镀铜溶液中硫酸铜和锌杂质的分析方法

酸性镀铜溶液中的锌杂质严重影响硫酸铜的测定结果。介绍了硫酸铜和锌杂质的分析方法。用三乙醇胺光度法测定硫酸铜,用EDTA容量法测定硫酸铜和锌杂质的总量,从总量中减去硫酸铜的量得到锌杂质的质量浓度。方法简单,快速而准确,能够满足监控酸性镀铜溶液的要求。     

系列液体和固体水分标准物质的研制

针对水分检测领域对标准物质的需要,研制了系列水分标准物质,包括4种液体水分标准物质,量值覆盖范围为0.139~47.6 mg/g,不确定度范围为0.012~1.1 mg/g;还包括3种含结晶水化合物水分标准物质,量值覆盖范围为50.7~156.3 mg/g,不确定度范围为0.6~1.3 mg/g,以及3种混合物水分标准物质,量值覆盖范围为0.142~9.90 mg/g,不确定度范围为0.013~0.20 mg/g。该系列液体和固体水分标准物质,适用于卡尔·费休库仑法和容量法水分仪的校准和检定,以及水分测量方法的验证,能够保障我国水分检测的量值准确和等效一致。     

铈盐滴定法测定铸造轴承合金中锑的含量

采用硫酸—硫酸钾溶解试样,以定量滤纸作还原剂,亚甲基蓝、甲基橙为指示剂,建立了硫酸铈铵滴定法测定铸造轴承合金中锑的分析方法。对测定条件、共存离子干扰进行了试验,方法的相对标准偏差在0.59%~1.42%之间,加标回收率在在97.4%~102.8%之间,标准样品测定值与标准值的相对误差在0.25%~1.71%之间,满足铸造轴承合金中1.5%~20%锑含量的测定。     

Synthesis of polyesters as binders for deinkable inks. II. Kinetics and mechanism of polyesterification between o-phthalic anhydride and neopentyl glycol in bulk at 200°C

The kinetics of the polyesterification in bulk at 200°C between o-phthalic anhydride and neopentyl glycol (2,2-dimethyl-1,3-propanediol) in a nonequimolecular ratio and in the absence of an external catalyst was investigated. The formation of the monoester and two dimeric compounds by uncatalyzed heating of o-phthalic anhydride with neopentyl glycol was virtually complete after dissolution of the anhydride. The data were analyzed statistically by a mathematical method due to Fradet and Maréchal for the estimation of the orders of reaction. This statistical adjustment of the data analysis supports the assumption that the kinetics of polyesterification in the absence of both the solvent and catalyst may be fitted to several orders of reaction over all the conversion. At first, our experimental data may be fitted to 3, or , or 2, etc., overall orders. The results establish that the overall kinetic order of the polyesterification depend upon the goodness of the experimental results and cannot be only selected by means of a correlation coefficient. If this last criterium is adopted, the polyesterification at low, medium, as well as at high conversions may be 3 as the most probable one, order one with respect to acid group concentration, and order two with respect to alcoholic group concentration, in agreement with Flory's predictions. A mechanism consistent with the most plausible kinetic results (I_m,n = 0.9990 and m, n = 1, 2) is proposed. It consists of a dimerization of the alcoholic groups followed by an attack of the acid to the dimer. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2409–2431, 1997     

Early and Degressive Putamen Atrophy in Multiple Sclerosis

Putamen atrophy and its long-term progress during disease course were recently shown in patients with multiple sclerosis (MS). Here we investigated retrospectively the time point of atrophy onset in patients with relapsing-remitting MS (RRMS). 68 patients with RRMS and 26 healthy controls (HC) were admitted to 3T MRI in a cross-sectional study. We quantitatively analyzed the putamen volume of individual patients in relation to disease duration by correcting for age and intracranial volume (ICV). Patient’s relative putamen volume (RPV), expressed in percent of ICV, was significantly reduced compared to HC. Based on the correlation between RPV and age, we computed the age-corrected RPV deviation (ΔRPV) from HC. Patients showed significantly negative ΔRPV. Interestingly, the age-corrected ΔRPV depended logarithmically on disease duration: Directly after first symptom manifestation, patients already showed a reduced RPV followed by a further degressive volumetric decline. This means that atrophy progression was stronger in the first than in later years of disease. Putamen atrophy starts directly after initial symptom manifestation or even years before, and progresses in a degressive manner. Due to its important role in neurological functions, early detection of putamen atrophy seems necessary. High-resolution structural MRI allows monitoring of disease course.     

硫酸-亚钛-钒酸铵容量法测定矿石中铀

用硫酸、氢氟酸、过氧化氧分解矿样，在6mol／L硫酸介质中，用亚钛将铀(Ⅵ)还原成铀(Ⅳ)。用亚硝酸钠氧化过剩的亚钛，过量亚硝酸钠用尿素破坏，以邻二氮菲亚铁为指示剂，钒酸铵容量法测定铀。本法ω(U)测定下限为0．03％，RSD优于3％，回收率为95％～105％，与铀矿石标准样品对照分析，误差小于2％。