红外光谱及其理论模拟在砷吸附过程中的应用

红外光谱技术具有分析速度快、分辨率高、灵敏度高、可以实时原位分析监测等优点。基于密度泛函理论对矿物吸附砷污染物体系红外光谱进行理论计算，分析对比红外光谱实测特征峰和理论计算特征峰，可以揭示砷吸附过程微观机制和表面化学形态。对红外光谱技术在水铁矿、赤铁矿、针铁矿等主要矿物吸附无机砷酸和有机胂酸的定性定量分析进行了综述，总结了红外光谱在无机和有机砷污染物吸附体系的定性定量研究及理论计算，为砷污染物精准检测分析和砷污染控制提供参考。     

高温高矿化度条件下驱油剂中聚合物分子结构形态及其在中低渗油层中的渗流特性

利用动态光散射(DLS)、电镜扫描(SEM)和岩心驱替实验等方法, 对高温高矿化度条件下聚合物溶液和“聚合 物/表面活性剂”二元复合驱油体系中聚合物分子线团尺寸及其影响因素和在中低渗油藏环境下的渗流特性进行了实验研究, 并对其渗流规律进行了机理分析. 结果表明, 在高温高矿化度条件下, 随聚合物浓度增加, 聚合物溶液和“聚合物/表面活性剂”二元复合驱油体系中聚合物分子线团尺寸D_h都呈现“先增大后减小”的变化规律. 非离子型表面活性剂以胶束聚集体形式吸附在聚合物分子链上, 造成二元复合驱油体系中聚合物分子线团尺寸D_h大于聚合物溶液. 在溶剂水矿化度较高和岩心渗透率较低条件下, 后续注入水的冲刷和稀释作用造成岩心内滞留聚合物浓度降低, 聚合物分子线团尺寸D_h增加, 最终导致聚合物溶液和“聚合物/表面活性剂”复合体系的残余阻力系数大于阻力系数.     

ICP-MS测定西藏热泉水中总砷

西藏地区热泉水矿化度较高,不同类型热泉水砷含量差异大。为快速准确测定其中砷的含量,建立了碰撞模式-电感耦合等离子体质谱测定热泉水中总砷的方法。研究了样品保存条件、样品稀释倍数、KED气流量等条件对测定结果的影响。通过优化仪器的工作条件、样品稀释等方法,消除了低分压和高矿化度的影响,运用碰撞池技术,有效消除⁴⁰ Ar³⁵Cl⁺、⁴⁰Ca³⁵Cl⁺、³⁹ K³⁶Ar⁺对砷的干扰。在样品中加入乙醇溶液,提高砷的灵敏度。结果表明:砷的检出限(3s)为0.22μg·L^-1,加标回收率在91.01%～108.96%之间,测定值的相对标准偏差(n=6)为2.2～4.5%,方法可以快速、准确测定西藏热泉水中总砷。     

PVA水凝胶的弹性和溶胀特性研究

采用硼酸与聚乙烯醇化学交联方法制备了聚乙烯醇(PVA)水凝胶,通过对PVA水凝胶的弹性与溶胀性能的研究,优选出交联剂硼酸与聚乙烯醇的最佳配比量;探究温度对PVA水凝胶弹性的影响以及时间、矿化度、温度对PVA水凝胶溶胀特性的影响。结果表明,随硼酸用量的增加,PVA水凝胶的溶胀率与弹性模量值都表现出先增大后减小的特征,当硼酸:PVA=10%时,PVA水凝胶的弹性和溶胀特性均最佳;PVA水凝胶在水溶液中溶胀率随时间的增长逐渐增大,40h后基本达到溶胀平衡;随矿化度的增大而减少,耐矿化度强,在10%盐度水中还能膨胀1倍,适用于高矿化度油藏;耐温性强,随温度的增大变化不大,适用于油藏温度。     

多孔有机聚合物吸附分离水体系中有机污染物研究和应用进展

有机物对水体的污染严重威胁生态环境安全和人类健康。 如何有效控制和消除水体系中的有机污染物是当前全球性热点问题之一,基于多孔材料的高效吸附是处理水体有机污染的有效方法。 多孔有机聚合物(Porous Organic Polymers,POPs)具有比表面积高、物理化学稳定性好、易修饰等特点,作为新型吸附剂在处理水体系有机污染方面具有广阔的应用前景。 本文综述了近10年来新型多孔有机聚合物对水体系中有机溶剂、农药与杀虫剂、有机染料等污染物的吸附分离研究进展。     

罗丹明B-砷锑钼兰离子缔合物分光光度法测定微量砷

测定微量砷有多种方法。本文介绍通过砷、锑、钼和罗丹明B在乳化剂OP的水溶液中形成离子缔合物的显色条件试验,提出了磷、硅、砷共存时高灵敏测定砷的分光光度法。该法通过控制酸度以消除硅干扰,并可不经分离和富集,在温度9℃以上直接于水相中测定水和土壤中的痕量砷。     

光催化降解污染物制氢反应与原位红外表征

研究了在Pt/TiO2悬浮体系中单组分和双组分污染物为电子给体光催化分解水制氢反应. 比较了污染物甲醛、甲酸和草酸为电子给体光催化放氢反应效率，发现其活性为：草酸 >甲酸 >甲醛.原位ATR（衰减全反射）红外研究结果表明，光催化放氢活性与污染物吸附特性有关.还研究了草酸与甲酸双组分污染物体系的光解水放氢和污染物降解动力学，发现总的放氢和污染物降解速率与污染物组分在TiO2表面的吸附强度和溶液浓度有关.污染物在TiO2表面的竞争吸附决定了反应动力学.原位ATR-IR方法研究双组分混合物体系的吸附，直观地证实了上述结果.     

高效液相色谱-电感耦合等离子体质谱联用同时测定鸡肉与鸡肝中的7种砷形态

建立了一种同时测定阿散酸、亚砷酸根、砷酸根、砷胆碱、砷甜菜碱、一甲基砷和二甲基砷等7种砷形态的高效液相色谱-电感耦合等离子体质谱分析方法。样品采用人工胃液作为提取液进行超声处理,再以碳酸铵溶液和水作为流动相,采用阴离子分析柱将样品提取液进行分离,最后进入电感耦合等离子体质谱测定。各砷形态在1～50 μg/kg范围内线性关系良好,相关系数r2均在0.999以上;在1、2、10 μg/kg 3个添加水平进行了方法学验证,平均回收率为84.3%～106.6%,相对标准偏差为1.4%～4.2%; 7种砷形态的定量限均为1 μg/kg。方法重现性好、灵敏度高、前处理简单,适用于鸡肉和鸡肝中主要有机砷和无机砷残留的分析检测。     

高效液相色谱-电感耦合等离子体质谱法同时测定果蔬中6种砷形态

建立了一种同时测定果蔬中亚砷酸根、砷酸根、砷胆碱、砷甜菜碱、一甲基砷酸和二甲基砷酸等6种砷形态的高效液相色谱-电感耦合等离子体质谱分析方法。样品经甲醇水提取,采用阴离子分析柱,50 mmol/L碳酸铵溶液和水作为流动相进行梯度洗脱,高效液相色谱分离,电感耦合等离子体质谱进行定性和定量分析。在0.5～50μg/kg范围内...     

乙醇对砷锑钼蓝测砷法的增敏作用研究及其应用

本文提出了一个利用乙醇的增敏作用,进行砷锑钼蓝测定痕量砷的高灵敏度的分析方法,对水中砷的检出限可达18ppt。通过对水、植物和钢铁中砷的分析,证明本方法具有较好的实用价值。对有机试剂的增敏作用进行了初步讨论。     

Blank values, adsorption, pre-concentration, and sample preservation for arsenic speciation of environmental water samples

Arsenic is the focus of public attention because of its toxicity. Arsenic analysis, its toxicity, and its fate in the environment have been broadly studied, still its blank values, adsorption to sampling materials and pre-concentration of water samples as well as stabilization of arsenic compounds in water samples under field conditions have been very little investigated. In this study, we investigate the blank values and adsorption of arsenic compounds for different laboratory materials. We focused our work onto pre-concentration of water samples and how to stabilize arsenic compounds under field conditions. When using glassware for arsenic analysis, we suggest testing arsenic blank values due to the potential release of arsenic from the glass. Adsorption of arsenic compounds on different laboratory materials (<10%) showed little influence on the arsenic speciation. Pre-concentration of methanol-water solutions could result in potential overestimation of arsenic compounds concentrations. Successful pre-concentration of water samples by nitrogen-purge provides an analytical possibility for arsenic compounds with high recoveries (>80%) and low transformation of arsenic compounds. Thus, concentrations as low as 1 ng As l⁻¹ can be determined. Addition of ethylenediaminetetraacetic acid (EDTA) and storage in the dark can decrease the transformation among arsenic compounds in rainwater and soil-pore water for at least a week under field conditions.     

Direct Determination of Arsenic in Natural Gasoline and Gas Condensate by Graphite Furnace Atomic Absorption Spectrometry Using an in situ Absorption Technique

Because arsenic poison catalysts during process operations and also is an environmental contaminant, the determination of total arsenic in natural gasoline, gas condensate and its products is of primary concern. Many methods available for the determination of arsenic require sample pretreatment and subsequent analysis on an aqueous matrix. Unfortunately, those methods could not get a satisfactory result because natural gasoline, gas condensate and its products may contain a variety of organic arsenic compounds which have lower boiling point than inorganic arsenic.     

Arsenic and its speciation in water samples by high performance liquid chromatography inductively coupled plasma mass spectrometry--last decade review

Arsenic composes a danger for human health all over the world as it is responsible for water resources contamination. The toxicity of arsenic depends on its chemical form. However, occurrence of particular arsenic species is dependent on processes occurring in water. Nowadays, more arsenic species is detected and analyzed in different kind of water (mineral, tap, waste), mainly owing to great possibilities resulting from coupling high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). This review mainly describes arsenic speciation analysis by HPLC-ICP-MS technique on the basis of articles that have been published since 2000. Arsenic chemistry, occurrence in different kind of water, total arsenic determination with interferences elimination and its validation and analytical performance are also reviewed.     

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.     

Determination of total arsenic and speciation of arseno-betaine in marine fish by means of reaction — headspace gas chromatography utilizing flame-ionization detection and element specific spectrometric detection

Marine organisms contain amounts of arsenic ranging from less than 1 μg/g to more than 10 μg/g. In food examinations usually total arsenic is determined, rarely As(III) and As(V) additionally. Rating marine food according to its total arsenic contents without further speciation, would involve an overcritical assessment. Due to the lack of suitable methods for routine analysis in food-control, the “organic” moiety remains unspecified. Only after performing a systematic research onto the real existence of arsenic and its compounds relevant to marine organisms, a toxicological evaluation can be carried out. As to its quantitative occurrence and its negligible toxic relevance arsenobetaine is of decisive importance. Therefore a reliable method has been developed based on headspace gas chromatography after chemical reaction. The predominant role of arsenobetaine in the organic arsenic moiety as well as in total arsenic in marine fish could thus be demonstrated.     

Determination of arsenic by galvanostatic stripping analysis and its application to steels

Arsenic can be determined by galvanostatic stripping analysis with a modified gold-film electrode, prepared by simultaneous electro-deposition of gold and arsenic on a glassy-carbon support. This initially deposited arsenic is stripped from the film before the electrode is used for the analysis, but its presence during the formation of the film apparently leads to uniformly distributed crystallization sites for the subsequent determination of arsenic, so that the precision of the determination is better than that obtained with an unmodified gold-film electrode. The pre-electrolysis is performed potentiostatically in a stirred solution of 7M hydrochloric acid, at a potential from -0.10 to -0.35 V (vs. Ag/AgCl). If the galvanostatic stripping step is performed in quiescent solution after a 6-sec rest-period, at a current of 2-12 muA, then for a 100-sec pre-electrolysis time the calibration curve is linear up to an arsenic concentration of about 2mug ml and the limit of determination is 8 ng ml . In the analysis of steel, the arsenic must first be separated by selective extraction of arsenic(III) bromide into toluene and back-extraction into the supporting electrolyte. A single extraction is virtually 100% quantitative. The relative error of the determination in steels is a few per cent and the results are in good agreement with the certified values for reference materials and with the results obtained by X-ray fluorescence analysis.     

Advances in On-Line Hydride Generation Atomic Spectrometric Determination of Arsenic

Flow analysis has played a major role in many areas of chemical analysis, making operations more robust and precise. It facilitates experimental studies opening new areas of research. In the field of arsenic research, there are various examples of surveys concerning arsenic determination and its species with the use of flow injection analysis (FIA) and sequential injection analysis (SIA). The increasing concern over the human exposure to arsenic and its species has necessitated the development of rapid, highly sensitive, precise, and accurate analytical methods for its determination in trace levels in environmental and biological samples. This review provides a literature survey on the automatic on-line hydride generation methodologies coupled to atomic spectrometry for determination of inorganic and organic arsenic species, during the last decades. All advances in on-line manifolds are categorized and highlighted. There are several reports of manifolds and setup instrumentation concerning hydride generation including continuous flow analysis (CFA), FIA, SIA, lab-on-valve (LOV), multicommutation flow systems, and hyphenated techniques. On-line preconcentration and pretreatment methodologies coupled with hydride generation such as solid phase extraction, co-precipitation and trapping are also discussed, as they are of particular interest in the development of fully automated methods.     

Determination of arsenic in surface waters of the Ob river basin

A simple voltammetric procedure for determining arsenic is conidered. It was tested in natural water and in substances suspended in river ecosystems of the Ob river basin. The results of analysis using the voltammetric procedure were verified by atomic absorption spectrometry after atomizing arsenic hydride in a fused-silica cell and by statistical methods employing standard criteria. Specific features of the electrochemical determination of arsenic and its spatial distribution in the Upper and Central Ob and in the Novosibirsk water storage basin were considered.     

微量元素砷与人体健康

讨论了砷在人体中的代谢，砷对人和动物的毒性影响，砷的生物学作用以及砷与癌症的关系。指出砷的毒性不仅取决于总量，更重要的是取决于化学形态；提示微量元素的形态与人体健康的关系应该作为从分子水平准确认识中草药中微量元素与中草药的药理生理活性关系的新思路；提出元素的生物活性与其存在状态的关系是药物拮抗作用和食物拮抗作用的实质。     

Solid sample graphite furnace atomic absorption spectroscopy for supporting arsenic determination in sediments following a sequential extraction procedure

Solid sample graphite furnace atomic absorption spectroscopy (SS-GFAAS) has been proposed since its appearance as a good alternative to wet methods of analysis in many matrices. Here, we examine the use of SS-GFAAS for total and leachable arsenic determination in sediments from distinct origins.Our direct analysis of seven selected sediments was not always free of spectral matrix interference, but the spectroscopic technique gave very good results for (a) direct arsenic measurement in solid residues from a range of leaching processes, (b) total arsenic determination (HNO₃ leaching test) and (c) the evaluation of its potential remobilisation (modified BCR three-step sequential extraction scheme). For the optimised instrumental conditions, the analysis limit was 0.44 mg kg⁻¹ and long-term reproducibility was between 10-15%.The sum of leachable arsenic in HNO₃ 65% and the residual fraction, gave recoveries from 72 to 118% of total arsenic content. These results are a good alternative to other cumbersome wet methods involving HF.