磷酸三丁酯萃取原子吸收光谱法测定微量Cr(Ⅲ)和Cr(Ⅵ)

常用的 APDC-MIBK 和 DDTC-MIBK 萃取原子吸收法一般只能测至十几个ppb 浓度的铬,且需在较高温度下进行萃取.本文报道一种用磷酸三丁酯(TBP)萃取原子吸收光谱法测定微量 Cr(Ⅲ)和 Cr(Ⅵ)的方法.实验表明,Cr_2O_7在盐酸介质中可与 TBP 形成 Cr(Ⅵ)-TBP-Cl-溶剂化合物,借此可测定0-0.25μg·ml~(-1)浓度范围内的 Cr(Ⅵ).若用 KMnO_4将平行试样中的 Cr(Ⅲ)氧化为 Cr(Ⅵ),测得总铬量,通过差减法即可算出Cr(Ⅲ)的含量.本法灵敏度高,准确度好.     

流动注射分光光度法测定微量硫氰酸根

基于３，５－Ｂｒ２－ＰＡＤＡＰ硫氰酸根分别与重铬酸根，铈（ＩＶ）在硫酸介质中反应成不稳定的蓝色产物，建立了两种测定微量硫氰酸根的流动注射分光光度新方法，在前一方法中，硫氰酸根含量在０．８０～７．２０ｍｇ／Ｌ范围内可定量测定，检出限为０．２７ｍｇ／Ｌ在后一方法中，硫氰酸根含量在０．８０～６．４０ｍｇ／Ｌ范围内呈线性，检出限为０．３０ｍｇ／Ｌ。当进样体积为１００μＬ时，进样频率为６０次／ｈ，所建立的两     

流动注射-结晶紫-磷钼杂多酸离子缔合体系光度法测定水中痕量正磷酸盐

在一定的酸度条件下,结晶紫与磷钼杂多酸离子缔合物的流动注射分光光度法可直接测定痕量磷.灵敏度高,重现性和选择性好.水中常见离子不干扰痕量磷的测定,工作曲线的线性范围为0～500μg·L~(-1)的磷,检出下限达1.0μg·L~(-1),以120h~(-1)采样频率,对各种天然水样进行测定,回收率为92.5%～105.0%,相对标准偏差为0.1%～6.7%.     

哌仑西平的单扫描示波极谱法测定

本报道一种测定哌仑西平的单扫描示波极谱法，在０．１ｍｏｌ／ＬＮＨ４Ｃｌ－ＮＨ３．Ｈ２Ｏ（ｐＨ８．０±０．１）缓冲液中，哌仑西平有一极谱还原波，其峰电位为－１．５１Ｖ（ｖｓ．ＳＣＥ），其一阶导数峰高与哌仑西闰浓度在６．６×１０＾－７－４．６×１０＾－６ｍｏｌ／Ｌ（ｒ＝０．９９８１）和６．６×１０＾－６－１．６×１０＾－５ｍｏｌ／Ｌ（ｒ＝０．９９９１）范围内有线性关系，检测限为３．４×１０－７ｍｏｌ     

银微电极微分电位溶出分析法研究

本文首次报道了银微电极微分电位溶出分析法。用化学刻蚀法方便地制作了银微电极，用于ＤＰＳＡ具有背景值低，分辨率好、精密度及灵敏度高，在不搅拌，仅需一定酸度而酸度而无其它介质的条件下就能测试等优点，对人工试样及自来水样分析，结果令人满意。     

Implementation and efficiency of an automatic peak-purity-control procedure in HPLC-UV-VIS-coupling based on principal component analysis

Summary Based on a thorough knowledge of the actual system precision significance testing of the primary eigen values, resulting from principal component analysis of the two-dimensional data array of HPLC with photodiode-array detection, is a powerful means to uncover unresolved chromatographic peaks. The implementation of this chemometric technique for assuring peak homogeneity and results showing the efficiency for two-component peaks in regard to spectral characteristics, chromatographic resolution and absorbance ratio of the investigated compounds are presented.     

Cyclocondensation of 2-Aminobenzimidazole with Dimedone and Its Arylidene Derivatives

The reactions of 2-aminobenzimidazole with substituted benzaldehydes and dimedone, 2-arylidene derivatives of dimedone, 9-arylhexahydro-1H-xanthene-1,8(2H)-diones and also with dimedone and DMF have been studied. The direction of formation of the pyrimidine ring has been established and discussed. An X-ray structural investigation of 2,2-dimethyl-2,3-dihydrobenzimidazo[1,2-a]quinazolin-4(1H)-one has been carried out.     

Molecular structure of (diethyldithiocarbomoyl)diphenylthiophosphinate

X-Ray study of (diethyldithiocarbomoyl)diphenylthiophosphinate was carried out. AZ-conformation of the diethyldithiocarbomoyl ligand, which results in a short nonvalent intramolecular P...S contact (3.315 Å), is realized in the molecule. Steric hindrances in the molecule increase the P-S-C bond angle to 106.39°.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1978–1980, October, 1995.The work was financially supported by the International Science Foundation (Gram RH1 000).     

Quantitation of diethylene glycol monoethyl ether in citrus oils

The use of diethylene glycol monoethyl ether as a flavor solvent is restricted. Since existing methods of quantitation are tedious or require sophisticated multi-dimensional GC instrumentation, a simple method has been developed using low cost GC-MS. Monitoring of ions 31 and 45 enables quantitation of DEGEE in essential oils at levels down to 1 μg/g with accuracy equal to or better than 15%.     

Pressure effects on the phase transition of urea adducts withn-paraffins and polyethylene

The decomposition of urea adducts with hydrocarbons is treated as a first-order phase transition and the pressure dependence is studied up to 0.7 GPa for several kinds of adducts. The thermodynamic quantities at the decomposition of the adduct can be analysed as a sum of those quantities of the component materials. The transition from the orthorhombic to the hexagonal form of the adduct with polyethylene is also investigated by X-ray diffraction and the pressure dependence of the lattice parameters is measured for the adducts. The results are compared with the phase transition in the pure paraffin.