食用菌中的总砷和砷形态分布研究

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结果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中的砷形态,准确测定了总无机砷与总砷含量。结果发现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,有一定食用风险,而蘑菇中总砷含量高,总无机砷含量却很低,主要以一甲基砷等其他无毒的砷形态存在,可以放心食用。结论食用菌中砷形态分布测定更能科学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总砷限量指标,建议进行修订。     

稻米中总砷及无机砷含量的测定与分析

采用氢化物原子荧光光度法测定13份稻米样品中的总砷和无机砷含量,结果表明：所测稻米样品中均检出总砷与无机砷,总砷含量范围为0.06~0.20 mg/kg,无机砷含量范围为0.039~0.150 mg/kg,无机砷占总砷的含量为50.0%~93.1%,无机砷含量在国家限量卫生标准以内;未冲洗大米样品中总砷含量仅为糙米的72.7%~90.0%,无机砷含量为糙米的62.7%~87.7%;多次冲洗的大米样品中总砷含量仅为未冲洗大米的75.0%~91.7%,无机砷含量为83.0%~93.6%。提高加工精度和用水淘洗均能在一定程度上降低总砷与无机砷的含量,减轻人们食用后对身体的危害。     

云南地区茶叶中总砷及无机砷含量调查分析

目的为云南茶叶的开发利用提供数据支持。方法利用国家标准方法对云南省110份茶叶样品的总砷和无机砷含量进行测试,并就产地、包装、流通环节等进行调查分析。结果经对采集的110个茶叶样品进行总砷检测,最高0.152 mg/kg,均值0.0325 mg/kg,仅1件检出无机砷,检测值为0.0591 mg/kg,均符合国家相关标准要求。总砷残留量在生熟茶和包装形态上的分布存在统计学差异,但不同原料来源地和不同品种上总砷残留量分布无统计学差异。总砷和无机砷残留量在分布上无相关性。结论云南省茶叶中总砷和无机砷含量属于较低水平,说明云南省茶叶生产有环境优势,砷含量整体控制在安全水平。     

粳稻谷中总砷和无机砷含量的测定及分布情况

本文采用ICP-MS法和LC-AFS法分别测定粳稻谷中的总砷和无机砷含量.结果表明:总砷在0?10 ng/mL的浓度范围内呈良好的线性关系,检出限为0.020 7 ng/mL;As3+和As5+在0?50 ng/mL的浓度范围内呈良好的线性关系,As3+检出限为0.24 ng/mL,As5+检出限为0.44 ng/mL...     

冻干松茸粉中总砷及无机砷的含量测定

目的测定冻干松茸粉中总砷及无机砷的含量。方法采用电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)、原子荧光光谱法(atomic fluorescence spectrometry,AFS)、液相色谱-电感耦合等离子体质谱法(liquid chromatography with inductively coupled plasma mass spectrometry,LC-ICP/MS)3种方法分别测定松茸中总砷及无机砷含量。结果ICP-MS、AFS测定冻干松茸粉中总砷含量分别为71.7、0.556 mg/kg,LC-ICP/MS测定冻干松茸粉中无机砷含量为0.0114 mg/kg。结论冻干松茸粉中砷主要以有机态存在,且不同检测方法以及前处理方式都会对实验结果产生影响。     

Determination of total arsenic, inorganic and organic arsenic species in wine

Forty-five wine samples from the south of Spain of different alcoholic strength were analysed for total arsenic and its inorganic [As(III), As(V)] and organic (monomethylarsonic acid [MMAA], dimethylarsinic acid [DMAA]) species. The As levels of the wine samples ranged from 2.1 to 14.6 µg l^-1. The possible effect of the alcoholic fermentation process on the levels of the total arsenic and arsenical species was studied. The average total arsenic levels for the different samples were very similar, without significant differences between all types of wines. In table wines and sherry, the percentages of total inorganic arsenic were 18.6 and 15.6%, with DMAA or MMAA being the predominant species, respectively. In most samples, DMAA was the most abundant species, but the total inorganic aresenic fraction was considerable, representing 25.4% of the total concentration of the element. The estimated daily intakes of total arsenic and total inorganic arsenic for average Spanish consumers were 0.78 and 0.15 µg/person day^-1, respectively. The results suggest that the consumption of these types of wines makes no significant contribution to the total and inorganic arsenic intake for normal drinkers. However, wine consumption contributes a higher arsenic intake than through consumption of beers and sherry brandies.     

Increase in rice grain arsenic for regions of Bangladesh irrigating paddies with elevated arsenic in groundwaters

Concern has been raised by Bangladeshi and international scientists about elevated levels of arsenic in Bengali food, particularly in rice grain. This is the first inclusive food market-basket survey from Bangladesh, which addresses the speciation and concentration of arsenic in rice, vegetables, pulses, and spices. Three hundred thirty aman and boro rice, 94 vegetables, and 50 pulse and spice samples were analyzed for total arsenic, using inductivity coupled plasma mass spectrometry (ICP-MS). The districts with the highest mean arsenic rice grain levels were all from southwestern Bangladesh: Faridpur (boro) 0.51 > Satkhira (boro) 0.38 > Satkhira (aman) 0.36 > Chuadanga (boro) 0.32 > Meherpur (boro) 0.29 microg As g(-1). The vast majority of food ingested arsenic in Bangladesh diets was found to be inorganic; with the predominant species detected in Bangladesh rice being arsenite (AsIII) or arsenate (AsV) with dimethyl arsinic acid (DMAV) being a minor component. Vegetables, pulses, and spices are less important to total arsenic intake than water and rice. Predicted inorganic arsenic intake from rice is modeled with the equivalent intake from drinking water for a typical Bangladesh diet. Daily consumption of rice with a total arsenic level of 0.08 microg As g(-1) would be equivalent to a drinking water arsenic level of 10 microg L(-1).     

Thermodynamic analysis of arsenic methylation

The Challenger mechanism for the methylation of arsenic is a repeating sequence of a two-electron reduction of pentavalent arsenic As(V) species to trivalent arsenic As(III) species followed by a methylation-oxidation reaction forming the successive methyl As(V) species. This unusual oxidation-reduction sequence prompted an examination of the thermodynamics of these reactions. Quantum chemical methods are employed to estimate the thermodynamic parameters for the methyl arsenic species. The sequence is thermodynamically favored at neutral pH for redox potentials with pe < 0 and methyl cation activities pCH3+ < -3 to -7 depending on the precise situation analyzed. The observed distribution of methyl arsenic species in human urine, which is remarkably constant across many studied populations, can be reproduced using an equilibrium model if the formation of TMA species is prevented. The estimated thermodynamic parameters are sufficiently accurate to evaluate questions of thermodynamic plausibility but not the precise details of speciation.     

Survey of total arsenic and arsenic speciation in US-produced rice as a reference point for evaluating change and future trends

Rice generally contains higher levels of arsenic than most terrestrial-based foods. Studies related to dietary intake of arsenic from rice must take into account arsenic speciation due to toxicity differences in arsenic species. In this study, microwave-assisted extraction with trifluoroacetic acid was used to prepare rice samples for arsenic speciation analysis by high-performance liquid chromatography-inductively coupled plasma mass spectrometry. Fifty-three samples collected directly from the fields in four major rice-producing states in 1980 and 1981 were analysed for total and speciated arsenic and the results were compared with each other and with results for several more recently collected samples from local markets. The average content of total arsenic was 210 ± 190 ng As g^?1. This study demonstrates that US rice samples with higher levels of total arsenic have higher levels of dimethylarsinic acid; however, inorganic arsenic levels, regardless of the total arsenic content, rarely exceed 150 ng As g^?1 dry weight. These data are consistent with more recent findings, thus establishing trends that arsenic content in US-grown rice has been relatively constant throughout the last 30 years. To the authors’ knowledge, the presented data are unique in that they provide a historical reference point for arsenic distribution in US-produced rice. These data would be invaluable for several applications including long-term arsenic exposure studies, environmental clean-up assessments, and to establish models for future trends in arsenic contribution in total diet studies.     

食品中无机砷分析技术进展

无机砷化合物于1980年被国际癌症研究机构确认为1类致癌物,其中关注度最高的是亚砷酸盐和砷酸盐。近年来,色谱和原子荧光或等离子体质谱的联用技术已经成为无机砷检测的主要方法,食品中无机砷检测一般分提取、分离和测定3个步骤。本文对无机砷检测各步骤的不同方法进行综述,并展望了食品中无机砷测定和风险评估的发展方向,以期为今后无机砷分析方法的开发提供新思路。     

根际-非根际土壤砷形态与三七根部砷赋存形态的相关性研究

本研究选取云南省典型砷污染土壤,以盆栽试验的方式,采用土壤砷形态分级连续浸提法和植物砷形态分级提取法,对三七生长的根际-非根际土壤中砷形态及三七中砷的赋存形态相关性进行研究。结果表明：(1)根际-非根际土壤中各砷形态含量由高到低的总体趋势为：残渣态＞结晶铁锰或铁铝水化氧化物结合态＞无定形和弱结晶铁铝或铁锰水化氧化物结合态＞专性吸附态＞非专性吸附态,残渣态所占比重最大,可达62%～86%。受根部活动的影响,非专性吸附态砷的含量均为根际土＞非根际土。(2)三七根部砷的赋存形态为F_r最高,含量为4.12mg/kg～7.60mg/kg。F_HAc和F_HCl虽迁移活性较弱但其所占的比例却不容忽视,最高可达25%。(3)根际-非根际土壤中不同砷形态与土壤总砷均呈正相关,其中残渣态R^₂=0.976。根际土中活性较强的非专性吸附态砷R^₂=0.499。(4)高砷土壤中砷形态与三七根部砷赋存形态间呈极显著相关,R^₂=0.992。中高砷土壤和中度砷土壤非根际土壤中的砷形态与三七根部砷赋存形态的相关系数较根际土有所升高,具有潜在砷毒害风险。     

海产品中砷形态分析研究进展

我国是海产品的生产和消费大国,所以海产品的安全问题受到人们越来越多的关注。海产品特别是食用海藻含砷量较高,但是海产品中的砷大部分以低毒性的有机砷形态存在,而且不同种类的海产品所含有的砷形态各不相同。所以,对海产品中的不同形态砷化合物进行精准分析检测,对于科学、客观评估海产品中砷污染的健康风险以及保证海产品的安全消费具有重要意义。海产品的砷形态分析面临的困难主要是,第一在不改变砷形态的前提下把海产品中所有形态砷化合物完全提取出来;第二把各形态有机砷和无机砷在较短时间内实现基线分离、并对各形态砷化合物进行高灵敏检测。近十多年来,有关海产品中砷的形态分析得到越来越多的关注,在方法学上也取得了显著的进步。本文主要针对近十多年来有关不同海产品中不同形态砷化合物的提取方法和分析检测方法方面的研究进展进行了概述,以期为食品检测机构或食品安全研究或评估人员提供方法学上的参考。     

午餐肉罐头中砷含量的测定

采用原子荧光光谱分析法测定午餐肉罐头中砷的含量,结果表明,所测样品中砷的含量为0.0125mg/kg,相对标准偏差为1.18%,检出限为0.0018ng/mL,回收率为98%～102.6%,该方法简单、快速、准确度高,适用于午餐肉中砷含量的测定。     

Modeling arsenic in the Patuxent Estuary

A water quality model was developed to track the fate and transport of four arsenic species in the Patuxent Estuary: arsenate (As(V)), arsenite (As(III)), methylarsonate (MMA), and dimethylarsinate (DMA). Processes simulated include mass transport, solid-liquid partitioning with suspended solids, uptake and transformation of As(V) by phytoplankton, oxidation of As(III), demethylation of MMA and DMA, and settling/deposition/ resuspension of particulate arsenic in the water column. A sediment module was also developed and linked with the water column to generate fluxes of inorganic arsenic from the sediment bed. The arsenic model was calibrated using water quality data from the Patuxent Estuary over a period ranging from May 24, 1995 to October 29, 1997. Model results indicated that transformation of arsenic by phytoplankton is not a significant source of DMA to the lower Patuxent. Instead, results suggested that the primary source of methylated arsenic (DMA and MMA) to the lower estuary is beyond the downstream boundary (Chesapeake Bay). However, model results supported the hypothesis that flux of arsenic from the sediment is a significant source of inorganic arsenic to the lower estuary.     

Phytofiltration of arsenic from drinking water using arsenic-hyperaccumulating ferns

Arsenic contamination of drinking water poses serious health risks to millions of people worldwide. Current technologies used to clean arsenic-contaminated water have significant drawbacks, such as high cost and generation of large volumes of toxic waste. In this study, we investigated the potential of using recently identified arsenic-hyperaccumulating ferns to remove arsenic from drinking water. Hydroponically cultivated, two arsenic-hyperaccumulating fern species (Pteris vittata and Pteris cretica cv. Mayii) and a nonaccumulating fern species (Nephrolepis exaltata) were suspended in water containing 73As-labeled arsenic with initial arsenic concentrations ranging from 20 to 500 microg L(-1). The efficiency of arsenic phytofiltration by these fern species was determined by continuously monitoring the depletion of 73As-labeled arsenic concentration in the water. With an initial water arsenic concentration of 200 microg L(-1), P. vittata reduced the arsenic concentration by 98.6% to 2.8 microg L(-1) in 24 h. When the initial water arsenic was 20 microg L(-1), P. vittata reduced the arsenic concentration to 7.2 microg L(-1) in 6 h and to 0.4 microg L(-1) in 24 h. At similar plant ages, both P. vittata and P. cretica had similar arsenic phytofiltration efficiency and were able to rapidly remove arsenic from water to achieve arsenic levels below the new drinking water limit of 10 microg L(-1). However, N. exaltata failed to reduce water arsenic to achieve the limit under the same experimental conditions. The significantly higher efficiency of arsenic phytofiltration by arsenic-hyperaccumulating fern species is associated with their ability to rapidly translocate absorbed arsenic from roots to shoots. The nonaccumulating fern N. exaltata was unable to translocate the absorbed arsenic to the shoots. Our results demonstrate that the arsenic-phytofiltration technique may provide the basis for a solar-powered hydroponic technique that enables small-scale cleanup of arsenic-contaminated drinking water.     

Accumulation of arsenic in drinking water distribution systems

The tendency for iron solid surfaces to adsorb arsenic is well-known and has become the basis for several drinking water treatment approaches that remove arsenic. It is reasonable to assume that iron-based solids, such as corrosion deposits present in drinking water distribution systems, have similar adsorptive properties and could therefore concentrate arsenic and potentially re-release it into the distribution system. The arsenic composition of solids collected from drinking water distribution systems (pipe sections and hydrant flush solids), where the waters had measurable amounts of arsenic in their treated water, were determined. The elemental composition and mineralogy of 67 solid samples collected from 15 drinking water utilities located in Ohio (7), Michigan (7), and Indiana (1) were also determined. The arsenic content of these solids ranged from 10 to 13 650 microg of As/g of solid (as high as 1.37 wt %), and the major element of most solids was iron. Significant amounts of arsenic were even found in solids from systems that were exposed to relatively low concentrations of arsenic (<10 microg/L) in the water.     

Total arsenic in rice milk

Rice milk and its by-products were tested for total arsenic concentration. Total arsenic concentration was determined using graphite-furnace atomic absorption spectrometry. The arsenic concentrations ranged from 2.7 ± 0.3 to 17.9 ± 0.5 µg L^?1. Rice milk and its by-products are not clearly defined as food, water or milk substitute. The US Environmental Protection Agency (EPA), the European Union (EU) and the World Health Organization (WHO) have set a level of 10 µg L^?1 for total arsenic concentrations in drinking water. The EU and the US regulatory agencies do not provide any guidelines on total arsenic concentrations in foods. This study provides us with a starting point to address this issue in the State of Mississippi, USA.     

Content of selenium, total and inorganic arsenic and bioaccessibility of arsenic in children diets of Mexico

BACKGROUND: The aim of this study was to evaluate the intake of selenium, total and inorganic arsenic and the bioaccessibility of arsenic in diets of Mexican schoolchildren using an in vitro method. RESULTS: Total and inorganic arsenic concentrations in the diets ranged from 0.05 to 1.15 mg kg^?1 dry weight (DW) and from 0.023 to 0.088 mg kg^?1 DW respectively, while selenium levels were between 0.08 and 0.20 mg kg^?1 DW. Daily intake of total and inorganic arsenic ranged from 0.15 to 10.49 µg day^?1 kg^?1 body weight (BW) and from 0.06 to 1.11 µg day^?1 kg^?1 BW respectively, while that of selenium varied from 0.29 to 2.63 µg day^?1 kg^?1 BW. Bioaccessibility of total and inorganic arsenic ranged from 4 to 97% (mean 44 ± 21.5%) and from 33 to 97% (mean 71 ± 22.5%) respectively. CONCLUSION: Inorganic arsenic levels in the diets were low. Therefore there appears to be a low risk of adverse effects resulting from excess inorganic arsenic intake from these diets. Copyright © 2011 Society of Chemical Industry     

XAS speciation of arsenic in a hyper-accumulating fern

The coordination environment and the redox speciation of arsenic in a newly discovered arsenic hyper-accumulating fern (Pteris vittata L) were investigated by X-ray absorption spectroscopy. This method allowed us to probe arsenic directly, i.e., with minimal sample preparation. The results indicate that arsenic is predominantly accumulated as As(III) in the leaves. XANES and EXAFS results show that As(III) in the leaves is primarily present as aqueous arsenite species. The plant actively maintains arsenic in this reduced oxidation state, because after sample collection and subsequent aging and drying of the plant material, As(III) is gradually oxidized to As(V). We think that these arsenite species are sequestered in vacuoles. At extremely high As concentrations (ca. 1% As per dry weight) arsenic in the fern leaves is coordinated to a significant degree by sulfur in addition to oxygen. This spectral signature indicates that thiol-rich compounds are implicated in the biochemical transformations of arsenic within the plant.     

Speciation of arsenic in Dutch total diets: methodology and results

In the last decade 311 duplicate portions of the 24-h diet of Dutch citizens were collected and lyophilized. All samples were assayed for total arsenic and, in addition, the 20 samples which ranked highest in total arsenic were selected for arsenic speciation i.e., the separate determination of organic-bound arsenic and inorganic arsenic. For the determination of total arsenic, the test portion is wet-digested and the digest reduced with KI/SnCl2/Zn to give AsH3 which is measured by molecular absorption spectrometry. Inorganic arsenic is also measured as AsH3 after acid extraction of the test portion and subsequent NaBH4 reduction of the extract. The residue of the acid extraction and the NaBH4-reduced extract are combined, wet-digested and the digest reduced with NaBH4 to give AsH3 originating from organic-bound arsenic. Samples spiked at different levels with inorganic and organic-bound arsenic were analysed and gave recoveries for inorganic arsenic of 94% to 122% (n = 6) and for organic-bound arsenic of 87% to 104% (n = 6). On average, the inorganic fraction is 30% of the total arsenic intake; range 3% to 50% (n = 14). The inorganic arsenic fraction decreases with increasing level of total arsenic intake. The highest oral inorganic arsenic intake was 60 micrograms; the tolerable daily intake (TDI) for a 60-kg individual is 120 micrograms inorganic arsenic. Organic and inorganic arsenic measured were summed and compared with the results of the total arsenic determination; differences were less than 15%. (Since inorganic arsenic is a contaminant and not an additive, the abbreviation TDI is preferred here over ADI (acceptable daily intake) which is retained for additives.)