HPLC-HG-AFS研究土壤-植物体系中As的形态

砷广泛存在于自然界中的有害元素之一.砷在土壤中的累积不仅影响植物、动物的生长和发育,而且通过食物链进入人体,直接危及人类健康~([1]).土壤中砷污染问题已经引起高度重视~([2]).     

碘从环境向人类食物链的迁移

综述了碘从环境向人类食物链的迁移，包括：碘在环境中的行为，在土壤-植物-人类系统中的迁移，碘在土壤中的化学形态及在自然界的循环，碘对动植物生长发育的影响，重点介绍了碘对人体的生理作用及对人类健康的的影响，最后对调控人体碘的水平提出了建议和对策。     

微波消解电感耦合等离子体发射光谱法测定羊栖菜中的砷

１引言 温州洞头所产药用海藻羊栖菜含有人体所需各种微量元素、１８种氨基酸和蛋白质,具有较好的药用和保健价值。目前,温州地区已形成较大的羊栖菜养殖基地,我们对羊栖菜营养成分研究,发现羊栖菜中含有较高的砷,砷对人体的毒害和药用功能早已引起人们的关注。本文采用微波消解电感耦合等离子发射光谱（ＩＣＰ－ＡＥＳ）测定了羊栖菜中的砷。测得羊栖菜中总砷为９１．３０μｇ／ｇ,９ｍｏｌ／Ｌ盐酸浸出砷为 ５５．３０μｇ／ｇ,大大高于国家规定砷的允许值。砷在羊栖菜中的化学形态和药用功能有待进一步研究。２实验部分２．１仪器…     

食品中砷允许含量和人体容许摄入量

我国规定每公斤粮食中含砷量不应超过０．７毫克,食用植物油不超过０．１毫克,酱、味精、井盐、矿盐和冷饮食品均不应超过０．５毫克,酱油和醋每升不应超过０．４５毫克。 体内微量的砷对健康无甚影响,世界卫生组织暂定人体每日容许摄入量为：每公斤体重不超过０．０５毫克。砷的摄入量在此范围内是安全的。 近来有些报道还认为,砷是动物和人体的必需微量元素。据报道,均匀饮食极微量的砷可使人体强健,肌肤更光润白嫩。食品中砷允许含量和人体容许摄入量     

三维荧光光谱技术在溶解有机质-吸附态砷相互作用中的应用进展

溶解有机质使含砷矿物还原溶解是地下水中砷富集的因素之一,三维荧光光谱技术可以进一步研究溶解有机质在砷迁移过程中的多重作用。本文从溶解有机质的组分、荧光特征指数以及荧光猝灭三个方面综述了三维荧光光谱技术在溶解有机质-砷相互作用中的应用。溶解有机质中的腐殖质组分会与砷形成络合物促进砷向地下水中迁移,还原性醌类充当电子穿梭体,增强了砷在水中的迁移性能。通过荧光指数、腐殖化指数和氧化还原指数可以判断溶解有机质的来源、腐殖化程度以及氧化还原态组分。地表水中砷浓度低,荧光指数高,腐殖化指数较低且以腐殖质物质为主;地下水中砷浓度和腐殖化指数较高,荧光指数低,且腐殖质的醌类部分较少,表明随着水中砷浓度升高,荧光指数成下降趋势,地表水中的腐殖质醌类充当电子穿梭加强了氧化铁的还原和砷迁移作用,促进地表水中的砷向地下水中迁移。砷和溶解有机质会形成砷-溶解有机质络合物,使溶解有机质发生荧光猝灭。pH值和金属离子会影响溶解有机质和砷的络合,但pH值主要影响溶解有机质自身的荧光强度,对砷-溶解有机质络合物的荧光强度影响不大,Ca²⁺能够明显增强溶解有机质-砷的类蛋白荧光。     

自然环境中砷的迁移转化研究进展

砷污染严重威胁着人类健康和生态系统安全,已成为全球性环境问题,砷在环境中的迁移转化及形态分布研究受到了人们的普遍关注。本文对近年来有关砷在环境中的迁移转化规律的研究进行了综述,重点论述了砷在自然水体中的迁移、在不同的pH和氧化还原条件下的环境行为,分析了在特定环境下砷的各种形态与不同的矿物质元素(如Fe,Mn,S等)的反应过程。最后,提出了今后值得进一步研究的重要方向,以为环境中砷污染的修复和治理提供一定的指导和参考。     

砷的生物地球化学

地下水和饮用水中低剂量砷引起的环境健康问题在全球范围内受到广泛关注.本文从生物地球化学行为的角度综述了关于砷在环境中迁移转化方面的研究进展.首先介绍了砷在土壤、水体和大气等介质中的分布、形态以及砷在这些介质中的循环.然后阐述了环境水体中控制砷迁移的两个过程即:砷在土壤表面的吸附-解吸和沉淀-溶解过程,并详细讨论了在吸附-解吸过程中生物、物理和化学等因素的影响.     

砷污染对植物和人体健康的影响及防治对策

讨论了土壤环境背景值及来源，地植物和人体健康的影响，砷的环境质量标准，国内外砷对环境的情况，以及砷污染防治对策。。     

雷公藤的药效及毒性与微量元素的研究

雷公藤是一种药效大、毒性也大的中药。研究了雷公藤的28种无机元素，发现其有益元素铁、锰、锌、硒含量较高．其有害元素铅、砷、镉含量也较高，与其药效和毒性一一相对应。雷公藤对风湿性关节炎、肾病、肝脏病、皮肤病的疗效．与铁、锰、锌、硒在人体中生物学机理一致。雷公藤对消比道、心血管、肝脏、泌尿系统、造血系统的毒害作用，与铅、砷、镉在人体中的生物学效应一致。所以在使用雷公藤时，应考虑到微量元素作用．可提高雷公藤的疗效，降低其毒性。     

镉从农业土壤向人类食物链的迁移

综述了镉在环境中的行为，在土壤－植物－人类系统中的迁移，由于粮食作物是镉进入人类食物链的主要来源，因此土壤污染的危害是全球性的，对决定农业系统中镉迁移动力学的关键过程、粮食作物中的镉含量、影响镉植物有效性的各类因子作了综述了讨论。     

Inorganic arsenic: A dangerous enigma for mankind

Human being have been using inorganic arsenic for a long time. Many reports on arsenic poisoning have been published: eg case reports, examination reports, post mortem reports, and epidemiological studies. Several aspects and features of arsenic poisoning are discussed in this report. Methods of inferring arsenic-related disease, disease classification according to acute or chronic criteria, exposure route, interaction, confounding factors, and the oxidation state of arsenic are all discussed. The effects of arsenic are classified into skin, respiratory system, gastrointestinal tract, liver, cardiovascular system, nervous system, and bone marrow effects. Carcinogenicity is an important chronic effect of arsenic poisoning, so special attention is paid to it in this review. In Japan, there have been many incidents of arsenic poisoning. In this review, we often use data from these cases, such as the Morinaga powdered-milk poisoning case, the Ube soy-sauce poisoning case, the Toroku mine incident, and the Nakajo well-water poisoning case. We emphasize here the necessity of planning follow-up studies and total health care for patients exposed to arsenic.     

Hydride generation-flame atomic-absorption spectrometry as an arsenic detector for high-performance liquid chromatography

Hydride generation-flame atomic-absorption spectrometry (HG-FAAS) was used as a continuous detection system for arsenic in the eluate from high-performance liquid chromatography (HPLC). Four arsenic species (arsenite, arsenate, monomethylarsonate and dimethylarsinate) were detected separately with the HPLC-HG-FAAS system equipped with an anion-exchange column. When hijiki (Hizikia fusiforme) extract was examined, arsenate was found predominantly and arsenite and dimethylarsinate were also detected. Liver supernatant fraction obtained from mice administered orally with arsenite was also studied with the HPLC-HG-FAAS system equipped with a gel permeation column. In addition to free or low-molecular-weight ligand-bound arsenic, high-molecular-weight protein-bound arsenic fractions were also detected.     

Determination of total cationic and total anionic arsenic species in oyster tissue using microwave-assisted extraction followed by HPLC-ICP-MS

A microwave-assisted digestion procedure was developed in presence of concentrated nitric acid (2.0 ml) and 30% hydrogen peroxide (0.20 ml) using a closed pressurized microwave digestion system for the determination of total anionic and total cationic arsenic compounds reside in oyster tissue. At 450 W for 15 min digestion, 74% of anionic arsenic, and 31% of cationic arsenic (105% total arsenic) were retrieved. At 300 W microwave power, 68% of anionic and 30.5% of cationic arsenic (98.5% total arsenic), and 100 W, 63% of anionic and 31% of cationic arsenic (94% total arsenic) were extracted out. The methanol water mixture (9:1) was cull out, exclusively 31.6% of anionic and 29% of cationic arsenic compounds (60.6% total). The dimethylarsinoylriboside (phosphate-arsenosugar) was the predominant arsenic species, along with arsenobetaine (AB), dimethylarsinic acid (DMA), inorganic arsenic, methylarsonic acid (MA), arsenocholine (AC), trimethylarsineoxide (TMAO) and tetramethylarsonium ion (TMI). Some other arsenic compounds, those were not matched with the retention time of the available standards, were also detected. Arsenosugar was fragile and adequately transmuted to DMA (100%), AB and AC to TMAO (100%) when 450 W microwave power was applied for 15 min. The separation and quantification of arsenic compounds in the microwave digests and extracts, were carried out in anion (PRP-X100) and cation (LC-SCX) exchange columns using ICP-MS as arsenic specific detector. The procedure was also validated by determining the total cationic and total anionic arsenic compounds present in DORM 1.     

Determination of trace amounts of arsenic using a capacitively coupled microwave plasma combined with hydride generation: applications to sewage sludge,iron and steels

A capacitively coupled microwave plasma (CMP) combined with an arsine generation system for the determination of trace amounts of arsenic is described. Factors affecting the spectral intensity of As 228.8 nm in the CMP were examined, and optimal working conditions for the determination of arsenic were established. A sensitive, precise and practical method for the determination of arsenic in sewage sludge, iron and steels was elaborated.     

Phytoremediation of lead with green onions (Allium fistulosum) and uptake of arsenic compounds by moonlight ferns (Pteris cretica cv Mayii)

Phytoremediation has been investigated as an alternative to excavation to remediate contamination in soil. In this work, Allium fistulosum (green onions) and Pteris cretica cv Mayii (moonlight ferns) were investigated for phytoremediation. Green onions were planted in lead-spiked soil, and chelating agents were introduced to enhance the uptake of lead by the plants. Lead uptake was low in the absence of chelating reagents. Ethylenediaminetetraacetic acid (EDTA) significantly enhanced the concentration of lead in the stems of green onions, while propylenediaminetetraacetic acid (PDTA) did not induce lead absorption.Moonlight ferns (P. cretica cv Mayii) were planted in a hydroponic system to which arsenic (III), arsenic (V), and monomethylarsenate (MMA) were added with hydroponic solution. Ferns exposed to arsenic (III) showed the highest extraction of arsenic followed by ferns exposed to arsenic (V). The extraction of arsenic by the ferns was higher when arsenic (III) was mixed with arsenic (V) than the combination of arsenic (III) and MMA. These results suggest that inorganic arsenic is phytoextracted preferentially to MMA.     

Arsenic and its speciation analysis using high-performance liquid chromatography and inductively coupled plasma mass spectrometry

It is known that arsenic has different toxicological properties dependent upon both its oxidation state for inorganic compounds, as well as the different toxicity levels exhibited for organic arsenic compounds. The field of arsenic speciation analysis has grown rapidly in recent years, especially with the utilization of high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS), a highly sensitive and robust detector system. Complete characterization of arsenic compounds is necessary to understand intake, accumulation, transport, storage, detoxification and activation of this element in the natural environment and living systems. This review describes the essential background and toxicity of arsenic in the environment, and more importantly, some currently used chromatographic applications and sample handling procedures necessary to accurately detect and quantify arsenic in its various chemical forms. Applications and work using only HPLC-ICP-MS for arsenic speciation of environmental and biological samples are presented in this review.     

Separation and determination of arsenic species in water by selective exchange and hybrid resins

A simple and efficient method for separation and determination of inorganic arsenic (iAs) and organic arsenic (oAs) in drinking, natural and wastewater was developed. If arsenic is present in water prevailing forms are inorganic acids of As(III) and As(V). oAs can be found in traces as monomethylarsenic acid, MMA(V), and dimethylarsenic acid, DMAs(V). Three types of resins: a strong base anion exchange (SBAE) and two hybrid (HY) resins: HY-Fe and HY-AgCl, based on the activity of hydrated iron oxides and a silver chloride were investigated. It was found that the sorption processes (ion exchange, adsorption and chemisorptions) of arsenic species on SBAE (ion exchange) and HY resins depend on pH values of water. The quantitative separation of molecular and ionic forms of iAs and oAs was achieved by SBAE and pH adjustment, the molecular form of As(III) that exists in the water at pH <8.0 was not bonded with SBAE, which was convenient for direct determination of As(III) concentration in the effluent. HY-Fe resin retained all arsenic species except DMAs(V), which makes possible direct measurements of this specie in the effluent. HY-AgCl resin retained all iAs which was convenient for direct determination of oAs species concentration in the effluent. The selective bonding of arsenic species on three types of resins makes possible the development of the procedure for measuring and calculation of all arsenic species in water. In order to determine capacity of resins the preliminary investigations were performed in batch system and fixed bed flow system. Resin capacities were calculated according to breakthrough points in a fixed bed flow system which is the first step in designing of solid phase extraction (SPE) module for arsenic speciation separation and determination. Arsenic adsorption behavior in the presence of impurities showed tolerance with the respect to potential interference of anionic compounds commonly found in natural water. Proposed method was established performing standard procedures: with external standard, certified reference material and standard addition method. Two analytical techniques: the inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectroscopy-hydride generation (AAS-GH) were comparatively applied for the determination of arsenic in all arsenic species in water. ICP-MS detection limit was 0.2 μg L⁻¹ and relative standard deviation (RSD) of all arsenic species investigated was between 3.5 and 5.1%.     

NIES certified reference materials for arsenic speciation

 The National Institute for Environmental Studies (NIES) recently prepared two candidate certified reference materials (CRMs) for arsenicals to meet the growing demand for the quality assurance of arsenic speciation analysis. The NIES candidate CRM No. 14 Brown Alga was prepared from Hijiki seaweed for the certification of inorganic arsenic content, and No. 15 Scallop was prepared from adductor muscle of scallop for the certification of arsenobetaine content. The preparation of the candidate CRMs is briefly described. Cooperative analyses for total arsenic content of the candidate CRMs have been underway. The preliminary speciation analysis at NIES revealed difficulty in establishing suitable conditions for extracting arsenic species from the materials. Chromatograms of arsenic species by a high performance liquid chromatography-inductively coupled plasma mass spectrometric detection system are presented to provide information about arsenic species present in these candidate CRMs.     

Elimination of the chloride interference on the determination of arsenic using hydride generation inductively coupled plasma mass spectrometry.

In the determination of arsenic, attention has recently focused on the speciation of As(III) and As(V). Reversed-phase HPLC can be used to efficiently separate these two arsenic species. When inductively coupled plasma mass spectrometry is used for arsenic detection, an isobaric interference at m/z 75 is caused by the presence of chloride in the sample. These experiments describe the use of hydride generation in conjunction with a polypropylene-membrane gas-liquid separator to completely eliminate the transport of chloride to the plasma. A detection limit of 0.46 ppb for As(III) was achieved with this system. The chromatographic resolution of the system was not compromised by the addition of the gas-liquid separator. A determination of the arsenic content of a NIST urine sample was performed to demonstrate the effectiveness of the chloride elimination.     

Flow injection electrochemical hydride generation atomic absorption spectrometry (FI-EHG-AAS) as a simple device for the speciation of inorganic arsenic and selenium

A flow-injection system for the determination of inorganic arsenic [As(III)/As(V)] and selenium species [Se(IV)/ Se(VI)] by electrochemical hydride generation, cryogenic trapping and atomic absorption spectrometry is described. A simple and robust electrochemical flow-through cell with fibrous carbon as cathodic material has been developed for the speciation of arsenic. A cold-trap system makes possible to eliminate interferences from methylated arsenic species. Without pre-reduction the system is selective to As(III) and Se(IV). The selectivity obtained with fibrous carbon as cathode material is compared to the selectivity obtained with a second electrochemical flow-through cell using a lead foil as cathode.