Determination of iron(II) with chemically-modified carbon-paste electrodes

The utility of carbon-paste electrodes modified with 2,2'-bipyridyl and Nafion for the differential pulse voltammetric determination of iron(II) in aqueous medium is demonstrated. The method is based on formation of the 2,2'-bipyridyl complex of iron(II) and its accumulation by the Nafion. The differential pulse voltammetric response of the accumulated complex is used as the analytical signal. The response was evaluated with respect to carbon-paste composition, preconcentration time, pH, iron(II) concentration and other variables. A 3-min accumulation period permits measurement of iron(II) down to 10(-8)M, and a relative standard deviation of 3.8% for 2 x 10(-6)M iron(II). Rapid and convenient chemical renewal allows use of a single modified carbon-paste electrode in multiple analytical measurements over several days. The proposed procedure was applied to the determination of iron in certified standard reference materials and trace iron in natural waters.     

光谱复杂的稀土基体中稀土杂质ICP光谱测定的一些问题

ICP激发光源以其独特的功能使ICP/AES技术在稀土分析中的应用日益广泛,在一定程度上取代了经典的直流电弧光谱法,但应指出,由于常规雾化器的低雾化效率(≤5％)和试样的高倍稀释,ICP/AES技术的实际检测能力的改善并不明显,本文用ICP光谱法测定了     

Ecdysteroids of a culture of tissues and cells ofAjuga turkestanica

The possibility has been studied of obtaining ecdysteroids — ecdysterone and turkesterone — with the aid of a culture of the tissues and cells of the plantAjuga turkestanica. Conditions have been selected under which the yield of ecdysteroids in the culture of tissues and cells is comparable with amounts of the same substances in the organs of the whole plant.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 51–52, January–February, 1990.     

在增溶剂存在下硫氰酸盐-结晶紫光度法测定微量钨

在明胶存在下,钨与硫氰酸盐和结晶紫生成可溶性三元缔合物,最大吸收波长为540nm,表现摩尔吸光系数为4.1×10~5 L·mol~(-1)·cm~(-1),钨在0～11μg/25ml范围内服从比尔定律。方法已用于测定岩石中微量钨。     

二氧化碳多相催化加氢的新进展

就近年来关于ＣＯ２活化、几个重要的ＣＯ２多相催化加氢反应及廉价氢的供给的研究进展进行综述。参考文献３４篇。     

N－烷基吡咯烷酮的合成

Ｎ－烷基吡咯烷酮的合成王锡臣，张颂培，祝钧（北京轻工业学院化工系北京１０００３７）关键词烷基吡咯烷酮，固－液相转移催化，合成Ｎ－烷基吡咯烷酮可用作香波增稠剂，染发烫发调理剂，啤酒、葡萄酒中多酚洁净化剂和洗涤去渍剂等［１］，其合成一般采用吡咯烷酮Ｎ－烷...     

Choice of preferred stationary phases for gas chromatography. Part II

Summary The regularities of changes of the polarity factors with the composition of mixed stationary phases are discussed. Values of the polarity factors of active solids, partitioning liquids and also colloidal stationary phases are compared. Part I: ref. [1].