Surface chemical analysis of raw cotton fibres and associated materials

The surface chemical composition of raw unscoured cotton was successfully investigated by the surface analytical techniques X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The presence of non-cellulosic material at the fibre surface was established and determined to be a complex mixture of fatty acids, alcohols, alkanes, esters and glycerides. The effect of scouring and bleaching was to reduce the surface concentration of these materials but even after aqueous processing some non-cellulosic material residue was still detected at the fibre surface.     

Binding Aedes aegypti densonucleosis virus to ion exchange membranes

Experimental and numerical results for binding Aedes aegypti densonucleosis virus (AeDNV) using anion and cation exchange membranes are presented. AeDNV particles are adsorbed by anion and cation exchange membranes providing the virus particles and membranes are oppositely charged. Q membranes which are strongly basic anion exchangers were the most effective. Dynamic and static capacities for Q membranes were found to be similar. A numerical model is proposed which assumes a log normal pore size distribution. By estimating the required parameters from static binding experiments, the model may be used to calculate the breakthrough curve for virus adsorption.     

Performance of the diffusive gradients in thin films technique for measuring Ca and Mg in freshwater

Measurements of the major cations Ca and Mg by the technique of diffusive gradients in thin films (DGTs) were systematically evaluated. The concentration in solution was calculated using Fick’s first law of diffusion from the directly measured flux to the DGT device. A selective cation exchange resin (Bio-Rad Chelex^®100), which has been used extensively with DGT for trace metals, such as Cd²⁺, Cu²⁺ and Ni²⁺, was used for this work.

Elution of Ca and Mg from the resin with 1 M HNO₃ was very reproducible. Measurements of Ca and Mg concentrations in synthetic solutions agreed well with the theoretical predictions. The negative response on uptake caused by lowered pH was investigated. Uptake was found to decline below pH 5. The capacity of the DGT device for Ca and Mg was also investigated to establish maximum deployment times for given concentrations.

Experiments with filtered and modified lake water show that DGT can be used to measure Ca and Mg when trace metals are present in the solution. An in situ deployment of DGT combined with an ultrafiltration study suggest that the Mg concentration measured by DGT is similar to the concentration found in the fraction <1 kDa.     

Unusual ion pairs and their relationship to acid ionization

Osmotic and activity coefficients, determined from isopiestic measurements, are presented for aqueous solutions of eight tetramethylguanidinium salts. It is proposed that both hydronium and tetramethylguanidinium ions are capable of forming stable ion pairs with many anions by means of bridged hydrogens forming six-membered rings and that these ion pairs are stable in rather dilute aqueous solutions.     

芳香酸淋洗液的单柱阳离子色谱法测定碱金属,铵离子和烷基胺

研究了邻苯二甲酸、苯甲酸和对羟基苯甲酸３种芳香酸分别做淋洗液的单柱阳离子色谱法分离测定Ｌｉ＋、Ｎａ＋、ＮＨ４＋、Ｋ＋、甲胺、乙胺和正丙胺７种物质。３种芳香酸做淋洗液均可将７种物质分离开，且分离结果差异不大。在淋洗液浓度相同的条件下，邻苯二甲酸做淋洗液测定的检出限较低。选择３．０ ｍｍｏｌ／Ｌ邻苯二甲酸做淋洗液测得了上述７种物质的检出限和线性范围，并进行了叶面肥试样分析，７种物质的加标回收率在９６．４％～９８．６％之间。     

Evaluation of a PVC‐Based Thionine‐Zeolite and Zeolite Free Membranes as Sensing Elements in Ion Selective Electrode

The construction and performance characteristics of thionine electrodes based on the ion‐pair complex thionine‐tungstophosphate and thionine‐mordenite zeolite embedded in a polyvinyl chloride (PVC) matrix is described. Thionine electrode based on the ion‐pair is used for the indirect determination of ascorbic acid by standard addition method.     

Transport properties and electroanalytical response characteristics of drotaverine ion-selective sensors

The construction and electroanalytical response characteristics of poly(vinyl chloride) matrix ion-selective sensors (ISSs) for drotaverine hydrochloride are described. The membranes incorporate ion-association complexes of drotaverine with tetraphenylborate, picrate, tetraiodomercurate, tetraiodobismuthate, Reinecke salt, and heteropolycompounds of Keggin structure—molybdophosphoric acid, tungstophosphoric acid, molybdosiliconic acid and tungstosiliconic acid as electroactive materials for ionometric sensor controls. These ISSs have a linear response to drotaverine hydrochloride over the range 8×10^–6 to 5×10^–2 mol L^–1 with cationic slopes from 51 to 58 mV per concentration decade. These ISSs have a fast response time (up to 1 min), a low determination limit (down to 4.3×10^–6 mol L^–1), good stability (3–5 weeks), and reasonable selectivity. Permeabilities and ion fluxes through a membrane were calculated for major and interfering ions. Dependences of the transport properties of the membranes on the concentrations of the ion exchanger and near-membrane solution and their electrochemical characteristics are presented. The ISSs were used for direct potentiometry and potentiometric titration (sodium tetraphenylborate) of drotaverine hydrochloride. Results with mean accuracy of 99.1±1.0% of nominal were obtained which corresponded well to data obtained by use of high-performance liquid chromatography.     

Determination of Total Reduced Thiol Levels in Plasma Using a Bromide Substituted Quinone

The exploitation of 2‐bromo‐1,4‐naphthoquinone (NQBr) as a selective redox label for the determination of reduced thiol functionalities (RSH) has been investigated. The system is selective for RSH functionality, giving distinct voltammetric signals for glutathione and cysteine but can also be adapted for broad spectrum thiol detection. Ion chromatographic protocols based on conductimetric detection enable total RSH analysis (protein and monomolecular moieties) within human plasma. Bromide released through the reaction can be easily quantified and integrated within normal IC measurements. The efficacy of the approach has been assessed and the response validated through comparison with the standard colorimetric technique.     

电迁移微离子色谱及其应用

本文提出一种新型的离子色谱方法,采用恒电流电场代替机械泵输送离子,研制出体积小、重量轻、成本低、易操作的电迁移微离子色谱仪,并检测了几种常见的阴离子,Cl~-、Br~-、NO_2~-的检测极限为10~(-11)～10~(-12)mol,峰高和保留时间重现性相对标准偏差均<3％,进样量与峰高的线性关系良好。