应用HPLC-HGAFS联用技术测定海产品中无机砷的研究

本文应用高压液相色谱-氢化物发生原子荧光(HPLC-HGAFS)联用技术测定海产中无机砷的含量研究。解决测定海产品中无机砷的实际问题,按常规的分析方法在海产品样品前处理过程中,将中间产物砷糖(AsS)分解产生的小分子有机砷二甲基砷(DMA)误报为无机砷(iAs),使得测量海产品中无机砷结果偏高的问题。     

新产品信息

“紫菜海带中无机砷严重超标”属误报吉天公司色光联用仪给出了正确的答案被新闻界和国家有关部门定性为“有毒”的紫菜、海带,新近经北京吉天仪器有限公司研制的色光联用仪检测认定为无毒,错案的原因为检测手段落后。北京吉天仪器有限公司利用我国自主知识产权生产的色光联用仪,弥补了国家标准检测方法的缺憾,纠正了一桩错案。一年多来,我国华南、华东等地区称,大量紫菜中无机砷超标;国家工商部门也报道了44.9%的紫菜、海带中无几砷超标;另据报道,一些检测单位按国标检测相关的海藻干制品的结果;无几砷超标率竟为百分之百。这些关于紫菜、…     

HPLC-ICP-MS法分析太湖沉积物中砷的形态及分布特征

以0.3 mol/L磷酸和0.1 mol/L抗坏血酸为提取试剂,对沉积物样品进行微波萃取。以2.0 mmol/L NaH₂PO₄/0.2 mmol/L EDTA(pH 6.0)为流动相,采用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术测定萃取液中As（Ⅲ）、As（Ⅴ）、MMA和DMA的含量。4种形态砷的色谱峰在10 min内可以得到完全分离,标准曲线线性良好,样品的加标回收率范围为94.2%~110%,样品中砷形态的提取效率为80.4%~98.7%。研究表明,太湖表层沉积物中的砷主要为无机形态,未检出有机砷形态,As（Ⅴ）形态的含量高于As（Ⅲ）,说明太湖表层沉积物基本上处于氧化性沉积环境中。近20年来,太湖湖底沉积物中砷的含量有了显著增加。检测的沉积剖面沉积物中砷的形态亦为无机形态,各沉积剖面沉积物中砷形态的相对比例没有显著差异。     

赛默飞世尔开发出检测苹果汁中砷的方法——色谱与质谱结合，实现高敏感度鉴别

2012年1月30日，赛默飞世尔科技（以下简称：赛默飞）公司，宣布其DionexICS-5000免试剂离子色谱系统可与ThermoScientificXSERIES2ICP-0-HS系统配合使用，通过由此创立的IC-ICP-MS法来检测苹果汁中的微量元素，包括有机和无机砷。     

辽宁海域捕捞水产品中无机砷的生物富集现象

辽宁省质检局连续两年对辽宁周围海域5个地区12个种类共194个捕捞水产品进行了7项检测。针对重金属无机砷的检测结果进行分析研究,发现所有检测样品的无机砷含量都不超出GB 2762-2012《食品安全国家标准食品污染物限量》规定,但无机砷的生物富集呈现上升趋势,尤其是甲壳类。说明甲壳类水产品对无机砷的生物富集作用较鱼类强。     

王水（1＋1）体系——双道原子荧光光度计同方法、同步测定土壤中的砷、汞

通过对王水（1＋1）消解土壤方法的优化,利用双道原子荧光光度计的双道检测优势,优化仪器条件,同方法、同步测定土壤中的砷和汞。结果表明：王水（1＋1）消解方法的优化可实现土壤中砷、汞的同步测定,这个方法是简便、快速、准确和精确的,提高了土壤中砷和汞的检测速度。     

高效液相色谱-氢化物发生-原子荧光法测定大米中的4种砷形态

本文建立了一种高效液相色谱-氢化物发生-原子荧光法测定大米中无机砷的新方法。该方法对4种砷形态的检出限为0.005～0.008μg/L,线性范围达2个数量级以上。将该方法用于大米中无机砷的检测,实际样品的加标回收率在95.7%～107.5%之间,样品连续进样5次,相对标准偏差(RSD)均小于5%。     

总砷超标食用菌样品中砷形态分布研究

目的:研究总砷超标食用菌样品中砷的形态分布,对食用菌中总砷含量与食用安全性的关系及其限量规定进行探讨。方法:从2010年深圳口岸进出口食用菌批量监测的各种食用菌样品中选择总砷超标的几类样品,采用液相色谱-氢化物发生-原子荧光光谱联用技术(LC-HGAFS)分析了不同种类食用菌样品中的砷形态,准确测定了总无机砷与总砷含量。结果:形态分析方法能够准确定性定量食用菌中的总无机砷含量,而食用菌中总砷含量和总无机砷含量并不存在对应关系。干香菇中总砷和总无机砷含量均较高,食用安全风险较高;而蘑菇中总砷含量高,但总无机砷含量却很低,主要以一甲基砷等无毒砷形态存在,可以放心食用。结论:食用菌中砷形态分布测定能更科学地体现砷超标和食用安全性的关系。我国现行食用菌卫生标准仅规定了总砷限量指标,建议对该标准进行修订。     

稻米中无机砷的提取与测定

通过与无机砷的2种国标提取方法的实验对比,建立高效、快速的微波辅助提取稻米中无机砷的方法,以0.3mol/L盐酸为提取剂,在60℃、固液比1:20的条件下微波加热提取15min,并用1%的L-半胱氨酸完成对As(V)的预还原。方法回收率为As(Ⅲ):94%～108%、As(V):92%～101%,精密度为2.94%,检出限为0.086μg/L,可准确用于稻米中有毒无机砷的定量检测和风险评估。     

原子荧光法测定水产品中的无机砷

对原子荧光光谱法测定水产品中无机砷的不同前处理条件进行了分析和比较，获得最佳试验条件。在最佳试验条件下，无机砷的方法检出限为1．0μg／kg，RSD=1．5％。在0．5，1．0，2．0mg／kg三种添加水平下，方法回收率范围为88．0～96．0％。     

L-半胱氨酸作还原剂测定肉及肉制品中无机砷

目的:建立使用L-半胱氨酸作为还原剂,氢化物-原子荧光光谱法测定肉及肉制品中无机砷的方法。方法:样品以6mol/L盐酸提取无机砷,样液用L-半胱氨酸作为还原剂,应用氢化物发生-原子荧光分析技术测定肉及肉制品中总无机砷。结果:方法的线性范围在0～30μg/L,相关系数r=0.9999(n=6),回归方程Y=51.7977X-7.7185,检出限为0.11μg/L,样品的相对标准偏差(RSD)为1.4%～3.5%,加标回收率为91.2%～93.7%。     

不同浸提方法对土壤及蜈蚣草中砷形态浸提效果

采用几种常见浸提方法对砷污染土壤和蜈蚣草样品进行处理,并使用LC-AFS测定砷形态,重点考察不同浸提方法对样品砷浸提效果的差异,以及其形态分布特征。结果表明:土壤和蜈蚣草中砷主要以As(Ⅲ)和As(Ⅴ)的无机形态存在。土壤、蜈蚣草根和蜈蚣草叶中As(Ⅲ)所占比例分别为11.6%,24.2%和73.8%。磷酸150℃高温浸提对土壤的浸提效率最高,可达41.0%;甲醇/水(1:9)超声浸提对蜈蚣草根和叶有最高的浸提效率,分别为60.2%和82.5%。样品加标回收率和相对标准偏差分别在92.7%～108.4%和2.05%～10.49%范围内。     

Effect of arsenic absorption on the water-refilling speed of Pteris cretica

Heavy metals are largely responsible for soil and water pollution. Recently, phytoremediation is receiving a large attention as a plant-based technology for removing metals from contaminated soil and water in an environment-friendly and cost-effective way. In such context, some species of ferns such as Pteris cretica were found to be a hyper-accumulator of arsenic (As). In this study, we first explored the validity of measuring the water-refilling process in xylem vessels of Pteris cretica using the synchrotron X-ray microimaging technique. Then we investigated the effects of arsenic concentration on the water-refilling speed inside the xylem vessel. The methodology to measure the water-refilling speed was consistent within five repetitions and 3 hours after the stem sample was cut from the plant. The water-refilling speed in the xylem vessels of the Pteris grown in arsenic solution was faster than that in normal water. Arsenic concentration of 0-1,000 μM was tested and the maximum speed was obtained at 500 μM. Conclusively, the experimental methodology developed in this study allowed to obtain some interesting results for understanding how arsenic affect the xylem sap flow transport and the mechanism by which growth is enhanced in the presence of heavy metal.     

Negative staining and cellulose microfibril size

Reason is given for the belief that an overlapping of images ensures a gross underestimate of cellulose microfibril width in plant cell walls observed both in section and negatively stained. Both theory and optical simulation of the electron-microscope situation suggest that the error involves a factor of at least two or three times. These, and other considerations render doubtful the existence of elementary microfibrils as components of the broad (c. 20 nm) microfibrils of some seaweeds.     

MassSpectrometryandAffinityChromatographyTechniquesforStudyingArsenic-BindingProteinsinHumanCells

Arsenic is one of the most important environmental agents in causing chronic human disease. Elevated levels of arsenic in drinking water may affect >100 million people around the world. A wide variety of adverse health effects, most seriously, cancers of bladder, lung, urinary tract, and skin, have been attributed to chronic exposure to arsenic. However, the biochemical mechanisms responsible for these effects caused by arsenic remain unclear, but may be mediated by the binding of trivalent arsenicals to thiol groups in proteins, thereby changing the conformation of these proteins and inhibiting their functions. If some of the affected proteins are responsible for cellular repair of DNA damage, for example, the inhibition of these proteins could lead to carcinogenesis. To study interaction of arsenic with proteins, we have developed an affinity selection technique, coupled with mass spectrometry, to select and identify specific arsenic-binding proteins from a large pool of cellular proteins. Controlled experiments using proteins either containing free cysteine(s) or inactive cysteine showed that the arsenic affinity column specifically captured the proteins containing free cysteine(s) available to bind to arsenic. The technique was able to capture and identify trace amounts of bovine biliverdin reductase B present as a minor impurity in the commercial preparation of carbonic anhydrase II, demonstrating the ability to identify arsenic-binding proteins in the presence of a large excess of non-specific proteins. Application of the technique to the analysis of subcellular fractions of A549 human lung carcinoma cells identified 50 proteins in the nuclear fraction, and 24 proteins in the membrane/organelle fraction that could bind to arsenic. This added substantially to the current list of only a few known arsenic-binding proteins. A number of arsenic-binding proteins identified using the affinity chromatography tandem mass spectrometry approach were of particular interest because of their important biological functions. For example, DNA-dependent protein kinase, ATP-dependent helicase II (Ku70), and topoisomerase 2 alpha, are involved in DNA repair and maintaining genome stability. Several other proteins modulate the redox status of cells, e.g. peroxiredoxin-1 and thioredoxin, and apoptosis, e.g., lamin A and heat shock cognate protein. This work shows that arsenic can bind to these proteins in cell extracts. How arsenic affects the function of these proteins in biological systems will have to be confirmed by studying arsenic interaction with proteins in living cells.