铅的吸收

人体中的铅主要来自食物、空气和水。根据对北京城区 4个幼儿园的调查 ,从粮谷类和肉菜类中摄入的铅约占膳食铅总摄入量的 45 3 %和 42 5 % ,这两类食物的铅摄入量占人体铅总摄入量的 87 8%。人体对铅的吸收则受到许多因素的影响 ,包括外界环境因素和人体本身的因素。此外 ,还与许多营养因子有关。(1 )胃肠道吸收 :成人胃肠道对铅的吸收率约为 5 %～ 1 0 % ,婴幼儿和儿童的胃肠道吸收率可达 42 %～5 0 %。铅的吸收与进食状况有关 ,Ｒａｂｉｎｏｗｉｔｙ (1 980 )的研究发现 ,胃排空时的铅吸收率要比胃充盈时增加约45 %。其他膳食营养因子…     

贵州兴仁煤砷中毒患者的死因调查与防治

运用高分辨率等离子体质谱法(HRICP-MS)测定了贵州兴仁居民燃用煤中砷含量,并调查了煤砷中毒死者详细资料。结果显示,当地居民燃用煤中砷仍然高度富集,从1976年到2003年,贵州兴仁砷中毒患者共死亡265人,其中死于癌症人数最多,死于肝硬化、腹水的病人其次,其中大部分患者死亡时间集中在1992年以后,说明贵州兴仁煤砷中毒的远期危害逐渐暴露,煤砷中毒的预防与防治应从各个方面全面进行。     

人体可通过呼吸吸收微量元素

在大气中悬浮的颗粒和气体中的微量元素不但可以通过与皮肤的接触进入机体,而且可以通过呼吸道的吸收进入机体。这是人体吸收微量元素的又一重要途径。     

皮肤的化学和皮肤的保护

本文介绍了皮肤的结构、功能的一般化学基础，讨论了化学物质的经皮吸收和引起的病变特别是各种职业病的化学特征，提供了皮肤保健如消毒、杀菌、护肤、美容等的有关化学信息。     

影响钙吸收的因素

不是所有食物中的钙都可以为身体所利用。在普通膳食中,摄入的钙通常仅20％～30％由小肠吸收并进入血液中。影响人体肠道吸收钙的因素有：     

原子吸收分光光度计用于分子吸收分析测定磷的研究

应用钙元素空心阴极灯中钙元素的４２２．７ｎｍ谱线和原子吸收分光光度计，对磷钒钼黄体系进行了研究，并对生铁样品中磷的含量进行了测定，获得满意的结果。     

膜的微波吸收机理

微波吸收现行理论将膜和材料混淆,把只能用于膜的反射损失(RL)性质用来表征材料,于是建立了错误的阻抗匹配理论和错误的膜吸收机理.阻抗匹配理论的不严谨表现为它有不同的定义,结果导致荒谬的结论如材料吸收的微波比进入材料的微波更多.这个事实说明阻抗匹配理论将孤立界面和在膜中的界面相混淆.阻抗匹配理论是建立在不可定义的物理量基础上的理论,存在严重缺陷.主流理论认为是材料本身具有多个吸收峰的性质导致(RL)有多个极小值.实际上均匀材料中的任何位置其微波吸收能力是一样的.微波在材料中传播的越远,被吸收的就越多,不会出现吸收峰.因而主流理论中膜的吸收峰又被错误地归结为材料的共振吸收.采用理论方法和自己实验室的实验数据,在波相消干涉的基础上建立了不同于当前主流理论的膜吸收机理并开拓性地应用了新理论.并指出文献报道的实验数据并不支持主流理论.同时通过已经发表的数据说明材料和膜的吸收机理不同,膜的吸收峰不是材料本身的属性,微波中的阻抗匹配理论应该用波的相消干涉理论取代.膜的多个吸收峰是膜特有的能量守恒所要求的、是角度效应的结果,需要用波的相消干涉分析,与材料的共振吸收没有任何关系.主流微波吸收理论混淆了实...     

氢氧化钠吸收硫化氢的工业技术讨论

硫化氢作为目前酸雨形成的原因之一,其排放量正越来越多的受到国家的重视,为此工业生产中各种处理硫化氢的工艺应运而生。本文首先对鼓泡式与塔吸收式的吸收方法进行对比讨论,同时在鼓泡式吸收的基础上,通过实验测定出氢氧化钠吸收硫化氢以及硫化钠吸收硫化氢的反应速率。     

原煤中有效态砷的提取方法

以1.0 mol/l,HNO3作为提取剂,用氢化物发生.原子荧光法(HG-AFS)测定提取液中砷的含量,建立了原煤中有效态砷的提取方法.考察了提取剂浓度、超声提取时间、液固比对原煤中有效态砷的提取效果的影响,在提取剂HNO3浓度为1 mol/L,超声提取时间1 h,液固比为15:1时提取效果最好.样品加标回收率为95.8%～98.O%.方法的线性范围为20～100 ng/mL,相关系数为0.9999,检出限为0.63 ng/mL(3σ,n=11).     

AFM Observation of Phospholipid Molecules Absorbed on Mica

An atomic force microscope was used to observe the adsorption of phospholipid molecules(phospha-tidylcholine, PC) on the mica substrate.The film-formation by PC molecules adsorption spontaneously on the specific substrate has been proved. It is revealed that the evident differences of morphology exist among different sampler with different concentrations of PC/decane solutions. different adsorption times, etc.The effect of tip-induced change in size of domains formed by adsorption of PC molecules on the substrate during the AFM scanning was observed.     

Photolytic oxidation of As species for determination of total As (including the ‘hidden’ As fraction) in coastal seawater by hydride generation-atomic fluorescence spectrometry

Ultraviolet irradiation (photolysis) in alkaline medium was applied for pretreatment of seawater samples so as to accurately determine total As by continuous-flow hydride generation-atomic fluorescence spectrometry. This sample pretreatment is meant to convert non-reducible As forms into inorganic As, which easily forms arsine. The optimised parameters were the treatment time and the pH of the medium. The behaviour of four hydride-reactive As species [As(III), As(V), MMA, DMA], and AsB, i.e. a typical non-hydride-reactive As species, when subjected to UV irradiation was studied. UV irradiation at pH 1 lead to conversion of all species into As(V) with the exception of AsB and DMA. Conversions of DMA and AsB into As(V) at pH 11 in less than 30 min were observed under UV irradiation. The limit of detection of As (measured as As(V)) by hydride generation-atomic fluorescence spectrometry was 0.1 μg/L and the repeatability of the oxidation procedure was about 10%. The method was applied to determination of total and directly reducible As at 11 sampling points of the Galician Coast (Atlantic Ocean, Spain). Total As concentrations were in the range 1.4-4.8 μg/L. A significant As fraction, between 20 and 44%, depending on the sampling point, corresponded to non-reducible As which was converted by UV irradiation into hydride-reactive As. This fraction should represent the sum of DMA, which yields a low sensitivity in the continuous flow-AFS system, and the hidden As fraction.     

Removal of As(III) and As(V) by natural and synthetic metal oxides

The removal properties of As(III) and As(V) by the several metal oxides having different mineral type and content of metals were investigated in batch and column reactors. The used metal oxides were Fe-oxide loaded sand (ILS), Mn-oxide loaded sand (MLS), activated alumina (AA), sericite (SC) and iron sand (IS). From the pH-edge adsorption experiments with AA and ILS, maximum As(III) adsorption was observed around neutral pH while As(V) adsorption was followed an anionic-type behavior. Among five metal oxides, AA showed the greatest removal capacity for both As(III) and As(V) through adsoption process but it has little oxidation capacity for As(III). Eventhough IS had much greater content of Fe-oxides than ILS, it showed a relatively lower removal capacity for both As(III) and As(V). This result suggests that adsorption of arsenic onto metal oxides is controlled by not only the contents of Fe-oxides but also mineral type of Fe-oxides. Column tests were performed at different combinations of metal oxides in a column reactor to find the best column system, which effectively treat both As(III) and As(V) at the same time. Among several combinations, the column reactors packed with MLS-AA and MLS-ILS showed a near complete oxidation of As(III) by MLS for a long time and the greatest adsorption of total arsenic compared to the column reactor packed with MLS-IS.     

Evaluation of As and Sb Mobility in Contaminated Stream Sediments

Single and sequential extraction procedures were applied to four sediment samples collected from an industrially polluted region of Eastern Slovakia. A sequential extraction procedure (SEP) for sediments recommended by the IRMM (Institute for Reference Materials and Measurements) – was applied and used as a reference extraction method. Single-step extraction (for soils) with 0.05 mol L⁻¹ ethylenediaminetetraacetic acid (EDTA) was slightly modified for this study of sediments. The removal ability of “Na₂EDTA extraction” was compared with the SEP recommended by the IRMM. After optimisation, the elements’ contents extracted into Na₂EDTA were in good agreement with the sum of the 1^st, 2^nd, 3^rd and 4^th step of SEP for As and Sb. Therefore Na₂EDTA extraction can serve as a supplementary test to the SEP recommended by the IRMM (under locally tested conditions). Alternatively, optimised extraction of sediments in chelating agents could be applied as an economically interesting and time-saving supplementary test to routinely used SEPs. This paper describes the sample preparation and the analytical results for each extraction step and compares the results with those of total element analyses (performed by an independent method) for As and Sb.     

原子吸收光谱分析饮料中砷的背景吸收及基体干扰

探讨了用原子吸收光谱直接分析饮料中砷时其背景吸收及基体干扰对测定结果的影响。结果表明，１ｍＬ的样品中加入改进剂１．５×１０－３氯化钯０．５ｍＬ，用１％硝酸定容至１０ｍＬ，可以克服背景吸收及基体干扰，且回收率高达９８．９６×１０－２。如果样品不多，用标准加入法测定，结果则更准。     

118例影响美容的五种皮肤病头发微量元素测定分析

对118例影响美容的痤疮、黄褐斑等5个病种进行了成人头发的Zn、Fe、Cu，Ca铡定和统计学处理，结果表明，各病的发锌和发钙普遗低于正常值，提示它们与微量元素关系。     

氢化物发生-原子荧光光谱法测定环境水样中的砷（Ⅲ）、砷（V）

用氢化物发生-原子荧光光谱法测定环境水样中的砷(Ⅲ)和砷(V)，在0～100μg／L范围内砷的浓度与荧光强度呈线性关系，相关系数r=0．9999。测定结果的相对标准偏差为0．7％，检出限为0．08μg／L。与二乙氨基二硫代甲酸银光度法进行比对，经F检验和t检验，两种方法无显著性差异。     

温莪术中As、Se含量的测定

对温莪术中As、Se两种元素的含量采用HG-ICP-AES法进行了测定分析。结果表明,温莪术全草中具有较高的Se元素含量和很低的As元素含量,从As和Se两元素含量的角度可见,温莪术具有一定的药用价值。并将温莪术经超声煎煮不同时间后得到的药液、药渣进行对比,发现As含量均很低,而Se含量在药渣中显著高于药液。     

原子荧光法测定田七中砷的含量

采用了硝酸+高氨酸消化样品,AFS-2202原子荧光光谱仪测定中药田七中砷的含量,该方法的检出限可达0.09μg·L~(-1),回收率在91.0％～109.2％之间。