Low-temperature electrothermal vaporization of thenoyltrifluoroacetone complex of Sc(III) and Y(III) for sample introduction in an inductively coupled plasma atomic emission spectrometry,and their determination in biological samples

A new method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace Sc and Y, based on gaseous compound introduction into the plasma as their thenoyltrifluoroacetone (TTA) complexes by electrothermal vaporization was developed. Using the reagent TTA as chemical modifier can not only enhance the analytical signals, but also reduce the vaporization temperature. At a temperature of 1,000 °C the trace Sc and Y can be vaporized completely into ICP. The factors affecting the formation of the chelate and its vaporization behavior, such as drying time, vaporization temperature/time, reaction medium and the amount of TTA, were investigated in detail. Under the optimized conditions (drying temperature/time 100 °C/10 s, vaporization temperature/time 1,000 °C/4 s), the limits of detection for Sc and Y were 19 pg and 34 pg (3), respectively, and the relative standard deviations for Sc and Y were 4.2% (c _Sc=0.2 g mL^–1; n=7) and 2.6% (c _Y=0.5 g mL^–1; n=7). The linear ranges of the calibration graphs cover three orders of magnitude. The method was applied to the analysis of the biological reference materials (GBW 07602, bush branches and leaves; GBW 07604, poplar leaves), and the results obtained were in good agreement with the certified values.     

Determination of the uronic acid composition of seaweed dietary fibre by HPLC

A high-performance liquid chromatographic (HPLC) method is described for determination of the ratio of beta-d-mannuronic acid to alpha-l-guluronic acid (M/G ratio) in dietary fibre of edible seaweeds. Total dietary fibre (TDF) content was determined gravimetrically. The TDF fraction was hydrolysed with 12 m and 1 m H(2)SO(4), then neutralized with AG 4 x 4 resin. The uronic acids were separated in a Tracer Extrasil SAX 5 micro m column (25 cm x 4 mm) at 35 degrees C, with 2 mm KH(2)PO(4) containing 5% methanol as mobile phase at a fl ow rate of 1.5 mL/min. The detection wavelength was UV 210 nm. The chromatographic identifications of beta-d-mannuronic acid and alpha-l-guluronic acid were confirmed by liquid chromatography-mass spectrometry (LC-MS). The method precision was 1.4% for beta-d-mannuronic acid and 3.5% for alpha-l-guluronic acid. The method was used to determine M/G ratio in canned seaweeds (Saccorhiza polyschides and Himanthalia elongata) and in dried seaweeds (H. elongata, Laminaria ochroleuca, Undaria pinnatifida, Palmaria sp. and Porphyra sp.).     

Open-access liquid chromatography/mass spectrometry in a drug discovery environment

The use of open-access mass spectrometry to monitor synthetic chemistry reactions, and also the integrity and purity of new chemical entities, has been a part of the medicinal chemist's tool-box for more than 5 years. Originally in our group at Wyeth Research there were two open-access methods available to the chemists, flow injection analysis (FIA) and liquid chromatography/mass spectrometry (LC/MS). The FIA method was approximately 3 min long, while the LC/MS method was approximately 20 min long (including an 8 min gradient). Within the first 2 years, the total number of open-access analyses increased by approximately 125%. It is interesting, however, that the number of LC/MS analyses increased by more than 285%. This is attributed to the fact that the chemists began using the LC/MS data to monitor reactions and also to check final product integrity and purity. In addition, the number of chemists performing parallel synthesis reactions has increased; thus, individual chemists can produce sample sets of up to 100 vials. This paper describes the implementation of new methodology, which accommodates the need for much faster run times and also the ability to acquire alternating positive and negative ion spectra within the same run. In addition, the instrument has been configured to e-mail the resulting processed data report to the submitting chemist. Several methods have been developed, including structure elucidation using in-source collision-induced dissociation (CID) and night-time analysis. The LC/MS methods for this system are described herein and are applicable to both industrial and academic synthetic chemistry optimization efforts.     

混合溶剂火焰原子吸收法直接测定原油中的镍

混合溶剂火焰原子吸收法直接测定原油中的镍刘广东袁存光张丙华刘文钦（石油大学（华东），山东东营２５７０６２）彭力（中国石油天然气总公司环保处，北京１００７２４）关键词原油，混合溶剂，无机盐标准，原子吸收法，镍测定原油中，微量元素镍、钒、铁、铜的存在对...     

废弃线路板化学分析采样、制样及检测方法

介绍废弃线路板中有回收价值元素和有害物质分析的采样、制样及检测技术。样品经过分类采样、剪切破碎和高温灰化制样,采用样品全分析或副批混合样分析。通过提高称样量、多次测定求平均值的办法,火试金富集-重量法测定贵金属金、银。湿法王水溶解样品,碘量法测定主体元素铜。电感耦合等离子体发射光谱(ICP-AES)法测定其它杂质元素,被测元素质量浓度在0~10μg/mL范围内与光谱强度呈良好线性关系,相关系数均大于0.9998。测定结果的相对标准偏差小于10%(n=5),加标回收率为97.0%~102.5%。该方法简单、快速,有效地解决了线路板样品不均匀而难采样,以及硬度、韧性强制样难,金属易包裹难分解的技术瓶颈,测定结果准确,具有代表性。该方法适用于废弃线路板化学成分分析,其它废弃电子产品检测可参考此方法。     

Role of Ion exchange in permeation processes

The single ion transport of transition metal ions like Cu²⁺, Co²⁺, Ni²⁺ and Zn²⁺ were carried out through the H⁺ and alkali metal ion forms of Nafion membrane. These studies showed that the ion exchange selectivity coefficient of the permeating ion had an effect on its transport process. It was found that the diffusion coefficient values (D) were directly proportional to the selectivity coefficient (K). This shows that the initial stage of permeation is governed by ion exchange process (effect of K on D).     

Particle circulation and oxygen mass transfer in an immobilized cell bioreactor

Two important considerations in the design of an aerobic particulate immobilized cell bioreactor are the provision of sufficient oxygen to maintain the desired metabolism of the immobilized organism, and the biomass holdup (which is proportional to the number of immobilized cell particles in the reactor). The Circulating Bed Reactor, a reactor developed for use with those forms of immobilization that result in particles of essentially neutral buoyancy, operates with an expanded bed of circulating particles. The particle number density attainable in such a reactor has been found to be dependent upon the circulation cell aspect ratio, the individual particle properties, the static bed voidage of the particles, and the superficial gas velocity. The oxygen mass transfer characteristics have been found to be dependent upon the circulatory nature of the system, the particle (solids) holdup, the particle porosity, and the superficial gas velocity.     

铈离子与氨基甲酸酯类化合物引发丙烯酰胺聚合的研究

本文对铈离子与苯基氨基甲酸酯类化合物在H_2O-CH_3CN(3∶1,V/V)及H_2O-HCONH_2(1∶2,V/V)两种介质中引发丙烯酰胺的聚合进行了研究。考察了不同结构的苯基氨基甲酸酯对聚合的影响。苯基氨基甲酸酯类化合物对铈离子引发聚合均有促进作用,其中对-甲苯基氨基甲酸酯的促进作用最为显著。测定了聚合反应表现活化能及聚合动力学方程,并提出了聚合反应机理。     

Molecular properties of hemicelluloses located in the surface and inner layers of hardwood and softwood pulps

The molecular properties of hemicelluloses located in the surface and inner layers of fibers present in hardwood and softwood pulps, together with the effects of different bleaching processes on these properties, have been investigated in this study. In order to separate the hemicelluloses located in these two layers, fibers were subjected to mechanical peeling and then separated by filtration into surface (filtrate) and inner layer materials. The materials thus obtained were characterized with respect to their polysaccharide compositions and uronic acid contents. The molar mass parameters of the hemicelluloses (extracted by alkali) were determined by employing size-exclusion chromatography in combination with off-line MALDI mass spectrometry. For all of the pulps examined, the relative content of xylan was found to be greater in the surface layer of the fiber than in the corresponding inner layer. The xylan polymers of the surface layer exhibited higher molar masses and lower frequencies of uronic acid side groups than did the xylans in the inner fiber layer. In connection with ozone treatment, hexenuronic acid residues in the surface layer xylan were removed to a greater extent than in the case of the inner layers, indicating a gradient for the reaction with ozone across the fiber wall. The xylan polymer remaining on the surface of the softwood pulps after completion of the chlorine dioxide bleaching process was predominantly uncharged.