Analysis of guanidine in high salt and protein matrices by cation-exchange chromatography and UV detection

A simple and sensitive HPLC method for quantitative determination of guanidine in high salt and protein matrices was developed. The HPLC system consisted of an Agilent 1100 pump with an online degasser, a UV detector, an autosampler, and Dionex CS 14 cation-exchange guard (4 mm x 50 mm) and analytical (4 mm x 250 mm) columns. The mobile phase was 3.75 mM methanesulfonic acid (MSA) with a flow rate of 1 mL/min. The other analysis parameters were: 50 microL injection volume, 195 nm UV detection, and 21 min runtime. The limit of quantitation (LOQ) for guanidine HCl was determined to be 0.25 mg/L and the standard curve ranged from 0.25 mg/L to 10 mg/L. Sample preparation was required for the samples containing high protein concentrations. Proteins were removed by centrifuging a sample in a 30 K NanoSep centrifugal filter at 15,300 x g for 20 min. The method could determine guanidine accurately in sample matrices containing up to 200 mM sodium ion or up to 50 mM potassium ion. The method can be used for clearance testing of guanidine in biopharmaceutical products.     

Hydrogenation of CO over carbides of tungsten

CO hydrogenation on tungsten carbides has been investigated.The methanation activitiesof tungsten carbides are comparable to that of supported Group VIII metal catalysts.Temperature-programmed thermal desorption spectra of CO on tungsten carbide show that CO is adsorbed non-dissociatively,and the surface—CO bond appears to be rather weak.     

配合物聚合反应研究──Ⅱ．以二氨基磺磷酸盐配合物合成聚脲

以二氨基磺酸盐配合物合成了一系列主链上合金属元素（Ｃａ，Ｎｉ，Ｃｏ，Ｃｕ）的聚脲聚合物．用ＩＲ和１ＨＮＭＲ对其结构进行了表征，以ＴＧ－ＤＴＡ研究了其热性能，并讨论了金属元素种类及其含量对聚脲聚合物溶液粘度的影响．     

偏最小二乘法在原子吸收光谱分析中的应用——钴和铟的同时测定

本文用偏最小二乘法（ＰＬＳ）校正了火焰原子吸收分析Ｉｎ２５２．１３７ｎｍ对Ｃｏ２５２．１３６ｎｍ的吸收线重叠干扰,对混合样中Ｃｏ和Ｉｎ的含量进行了测定,结果令人满意。