Name: determination of inorganic arsenic in a wide range of food matrices using hydride generation - atomic absorption spectrometry.
Uploaded: 2017-09-01T13:00:00.000+00:00
Duration: 8 min 21 s
Description: Watch this Scientific Journal Video about Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry. at JoVE.com

作者感谢 Dr. f. Cordeiro JRC 对数据的统计处理进行有益的讨论。对生物矩阵中的 iAs 进行分析的专家实验室承认, 在临时分所和实验室中提供的结果将被用作分配的价值。

注意: 所用的所有材料都需要用 10% (米/v) 硝酸 3 进行净化处理, 并至少用两次去离子水冲洗. 
 1. 水解 <ol> <li> 在4毫升聚丙烯离心机管中精确地将0.5 至1克冻干样品 (或同等数量的新鲜匀浆样品 如 1 至50克) 放在螺钉盖上. </li>
	<li> 添加4.1 毫升去离子水. </li>
	<li> 用一个机械振动筛搅拌5分钟, 直到样品完全湿了. </li>
	<li> 添加18.4 毫升浓盐酸 (HCl), 不少于37% 米/五 v </li>
	<li> 用机械振动筛搅拌15分钟 </li>
	<li> 让休息12-15 小时 (例如过夜). </li>
</ol> 2。提取 <ol> <li> 添加2毫升的氢溴 (评论) 不小于48% 米/v 和1毫升的肼硫酸 (N 2 H 6 如此 4 ) 解决方案 (15 毫克/毫升) 的水解样品. </li>
	<li> 震动三十年代与一个机械振动筛. </li>
	<li> 添加10毫升氯仿 (CHCl 3 ). </li>
	<li> 震动5分钟, 用一个机械振动筛. </li>
	<li> 离心5分钟, 800 x g. </li>
	<li> 将氯仿相 (下相) 移入另50毫升聚丙烯离心管. </li>
	<li> 再加入10毫升氯仿到剩余的酸相并重复萃取。在末端大约20毫升氯仿应该被收集了。注意避免在酸相中产生交叉污染. </li>
</ol> 3。清除氯仿阶段 <ol> <li> 将池中的氯仿阶段离心5分钟, 在 800 x g。如果需要, 离心时间或速度可能会增加, 以实现两个阶段的明确分离. </li>
	<li> 用1毫升吸管移除氯仿上剩余的所有酸相残留物。这一步是至关重要的。任何残留在氯仿相中的酸相残基都会导致过高估计的 iAs 结果, 因为样品中的所有其他砷都存在于酸相中. </li>
	<li> 通过疏水性聚四氟乙烯膜 (25 毫米直径) 过滤, 除去氯仿相中存在的剩余固体或酸相残留物, 并在50毫升聚丙烯离心管中收集氯仿相. </li>
</ol> 4。后提取 <ol> <li> 将10毫升的1米 HCl 添加到从过滤步骤后收集的氯仿阶段提取的 iAs. </li>
	<li> 震动5分钟, 用一个机械振动筛. </li>
	<li> 离心5分钟, 800 x g. </li>
	<li> 吸管的酸相 (上相) 和倒入250毫升玻璃烧杯 (, 如 Pyrex) 的矿化. </li>
	<li> 重复后提取并合并收集的 HCl 阶段. </li>
</ol> 5。样品矿化 注意: 此步骤允许消除在 iAs 质量分数接近或低于量化限制的示例中的干扰和预, 并且实验室经常省略它使用该协议与 ICP-MS 作为最终决定, 而不是汞原子吸收光谱法. 
<ol> <li> 暂停20克硝酸镁六水合物 [Mg (无 3 ) 2 6H 2 O] 和2克氧化镁 (氧化镁) 在去离子水100毫升。在玻璃烧杯中加入2.5 毫升的悬浮液。在加入时摇动悬浮液以避免沉淀. </li>
	<li> 添加10毫升浓缩硝酸 3 至少65% 米/v, 并蒸发到干燥在砂浴 (或热板), 避免任何预测。为了验证样品是否完全干燥, 在玻璃烧杯的顶部放置一个手表玻璃, 并检查不形成冷凝. </li>
	<li> 用手表眼镜盖住烧杯, 并将其置于一个不超过150和 #186 的初始温度下的消音器炉中; c、逐步将温度提高到425和 #177; 25 和 #176; c 的速率为50和 #176; c/小时保持在425和 #176; c 为 12 h。这一步至关重要。为了避免任何预测, 气温上升的速度必须严格执行. </li>
	<li> 允许骨灰冷却到室温. </li>
	<li> 添加0.5 毫升去离子水湿灰, 然后加入5毫升的 6 M HCL。小心从玻璃烧杯的墙壁中回收所有的灰烬。完全溶解火山灰, 必要时摇动. </li>
	<li> 添加5毫升的 pre-reducing 剂, 通过溶解5克碘化钾 (基) 和5克抗坏血酸, 在100毫升去离子水中制备, 并等待30分钟, 以达到定量减少 iAs 为 (III) 的目的. </li>
	<li> 通过惠特曼数字1的纸张或等效过滤解决方案, 并将其收集在50毫升聚丙烯离心管中。用6米的 hcl 冲洗玻璃烧杯两次. 在25毫升的管子中收集冲洗液, 并使其达到最后的体积与 6 m hcl 注意: 当样品中的 iAs 浓度预计接近或低于方法的量化限度时 (0.010 毫克/千克), 或相反, 高, 矿化步骤 5.5-5.7 应使用 表 1 中给出的卷进行修改, 这将提供更低的量化限制。在4和 #176, 重新溶解和预样品稳定24小时;整个分析过程至少应使用两个试剂毛坯. </li>
</ol> 6。校准 注意: 为了量化起见, 请在 0.5-10 和 #181 范围内使用 as (III) 的外部校准曲线; g/l 使用1000毫克/升作为 (V) 商业上可用的认证标准解决方案来构建校准曲线应用后续稀释. 
<ol> <li> 以1000毫克/升标准溶液的移1毫升, 在100毫升的容积烧瓶中准备10毫克/升为 (V) 标准溶液, 并以 6 M HCl 填充至标记. </li>
	<li> 将0.1 毫克/升作为 (v) 标准溶液以移1毫升的10毫克/升作为 (v) 标准溶液, 在100毫升容积烧瓶中, 并以6米 HCl 填充至标记. </li>
	<li> 准备25和 #181; g/l 作为 (v) 标准溶液移25毫升的0.1 毫克/升作为 (v) 标准溶液在100毫升体积烧瓶和灌装到标记与 6 M HCl. </li>
	<li> 准备如下 (III) 的校准曲线: 从25和 #181 的移液管; 以 g/L 作为 (V) 标准解决方案所给出的容量 表 2 到50毫升容量烧瓶中, 在每个容量烧瓶中添加10毫升的 pre-reducing 溶液, 等待30分钟,然后用6米 HCl 填充标记。其他卷是适当的, 只要它们保持上面描述的比例. </li>
	<li> 准备一个校准空白, 如下所示: 吸管10毫升 6 M HCl 和10毫升 pre-reducing 溶液在一个50毫升容量烧瓶。等待30分钟, 然后填入标记与 6 m. </li>
	<li> 使用标记为 QC1 和 QC2 的标准 表 2 作为质量控制: QC1 确保低浓度水平的定量是正确的和 QC2 的, 确保在高浓度时的反应是稳定的, 没有显着漂移时间. </li>
</ol> 7。确定 <ol> <li> 使用具有样、流动注射-氢化物生成系统和电热加热石英电池的原子吸收光谱仪, 用于检测和量化目的, 并遵循仪器在 表 3 中列出的用于对 iAs 进行定量分析的条件. </li>
</ol> 8。量化 <ol> <li> 计算 iA分析样品中的质量分数 (用 mg/千克表示), 使用以下公式: <img alt="Equation 1" src="/files/ftp_upload/55953/55953eq1.jpg"/> Where: C x : 提取物中的浓度 (和 #181; g/L),从校准曲线 C BI : 试剂空白样品 (和 #181; g/L) 中的浓度, 从校准曲线推断出: 样品成矿步骤的最后体积 (5.7), 通常 v = 25 毫升 w: 样品重量 (以克为) </li> </ol>

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作者没有什么可透露的。

所描述的协议中的一个关键步骤是清除氯仿阶段 (步骤 3.2), 因为在氯仿阶段剩余的任何酸性相残留物都会导致过高估计的 iAs 结果, 因为样品中的所有其他砷种类都存在于酸中。阶段.这是特别相关的, 当分析海洋样品由于存在大量的有机物种, 这可能占大多数的砷质量分数在样品中存在。使用疏水性聚四氟乙烯 (3.3) 膜是至关重要的。如果在将 iAs 提取成氯仿时形成乳液, 则可以增加离心 (3.1) 的速度。其他传统的消除乳液的方法也可以应用。另一个关键的步骤是矿化 (步骤 5.3)。必须严格执行提高温度的速度, 以避免任何将减少 iAs 恢复导致不受控制的负偏倚的预测, 并可能对分析员造成危险。
如上所述, 一些实验室采用了电感耦合等离子体质谱法, 而不是用保汞原子吸收光谱方法进行评价。在这种情况下, 不需要干灰化步骤 (协议中的步骤 5), 1 M HCl 阶段可以引入 ICP-MS。在 HG 原子吸收光谱法中, 由于其检测限较高, 预步也消除了可能的干扰, 是必要的。
本文所述方法所取得的满意结果, 无论是与无藻的结果, 均与 HPLC-电感耦合等离子体质谱法相媲美, 且高于汞原子吸收光谱。后一种技术 (HG-原子吸收光谱法) 广泛存在, 但容易受到有机砷种类的干扰, 特别是在具有复杂砷种类分布模式的食品商品中。取得满意结果的最低百分比是用 "其他方法" 获得的, 但必须牢记, 它涵盖了若干分析方法, 其中每一个都以少量结果表示,图 1。本文提出的方法是一种替代更复杂的/昂贵的 HPLC-ICP-MS, 仍然具有类似的性能, 即使在复杂的矩阵。频繁地使用连字符技术, 例如 HPLC-ICP-MS, 需要高合格的操作员和昂贵的红外线结构。本文所提出的方法可以由任何受过基础分析化学训练的分析员来实施。
与该方法相关的一些主要缺点。这是很耗时的, 因为必须遵循几个步骤, 将 ias 与其他砷物种分开, 并将预 ias 降低到甚至 sub-ppm 水平。它意味着使用氯仿。在实验室中有一种避免使用氯化化合物的趋势, 因为它们可能会对健康产生负面影响。然而, 如果保持良好的实验室做法, 并在油烟罩中处理样品, 可以避免这些负面影响。MMA 将干涉国际会计准则的确定。在分析甲基丙烯酸甲酯可能存在的样品时, 必须牢记这一点, 如藻类、鱼类和其他海鲜。然而, 甲基丙烯酸甲酯通常存在少量, 这将由与获得 iAs 结果有关的不确定性所覆盖。

自2016年1月以来, 一些大米商品中的无机砷 (iAs) 的最高水平已列入委员会条例 (EC) 1881/2006 确定食品中某些污染物的最高水平1与0.10 µg/升大米为目的地生产婴幼儿食品, 0.20 µg/non-parboiled 米 (抛光或白米), 0.25 µg/米, 谷米大米和糙米大米, 0.30 µg/升大米华夫饼, 大米片, 大米饼干和年糕。欧洲食品污染物立法的最新进展遵循了欧洲食物安全局 (局)2食品中砷的科学观点, 据估计, 通过饮食对一般和高消费者的影响欧洲是这样的, 可能会给一些消费者带来风险, 记住长期接触 iAs 会导致肺癌、皮肤和膀胱以及皮肤病变。在局的科学报告中, 对欧洲人口中的无机砷进行膳食接触的情况3, 2014年发表的结论是, 对所有年龄的消费者来说, 对国际会计准则的主要贡献者是加工产品, 而不是谷物大米和大米、牛奶、奶制品和饮用水对 iAs 的摄入有很大的贡献, 牛奶和奶制品是幼儿和婴儿的主要贡献者。
在 2010年, 欧洲联盟饲料和食品中的重金属 EURL 实验室对大米中的 ias 进行了一次熟练度测试, IMEP-107, 证明在大米中测定 ias 是有可能的, 无论分析方法使用4。
为确定食品中的 iAs, 已对几种分析方法进行了验证。中国是第一个在其立法中引入稻米最高水平的国家。为了使立法的实施成为可能, 2003年公布了标准方法, 以确定标准中的什么叫做 "无机-砷"5。欧洲标准化委员会 (岑), 出版在2008年一个规范化的方法, EN 15517:2008, 为 iAs 的决心在海藻6。这两种方法基于优化条件的使用, 仅从 iAs 生成砷。这样, 就不需要从其他砷种类中分离出能产生砷氢化物的 iAs。最后的决心是通过原子荧光5或氢化物发生原子吸收光谱法, HG 原子吸收光谱仪6完成的。然而, 在不受其他砷化合物干扰的情况下, 很难确定产生砷氢化物的确切条件, 而在 IMEP-112 (PT 组织的 EURL) 中所报告的藻类的所有质量分数都是由这两种方法获得的。被计分了作为令人不满的7。砷物种, 如 monomethylarsonic 酸 (MMA), dimethylarsinic 酸 (DMA), 和 arsenosugars 目前在藻类样本, 可以产生挥发性的氢化物太多, 可能会干扰的决定, 导致一个积极的偏差在结果8.
最近, 岑发表了一个新的标准方法, EN 16802:2016, 用于测定海洋和植物来源的食品中的 iAs 使用 HPLC-ICP-MS9。并非所有的实验室都配备了这种类型的仪器和 non-expensive, 需要直接向前的方法, 特别是在实验室基础设施较不发达的国家。
在 2012年, 岑通过固相萃取 (SPE), EN 16278:201210, 在微波萃取和离线分离 ias 后, 用汞原子吸收光谱法测定动物饲料中的 ias。这种方法被证明是适合的分析在饲料中的 ias 可能缺乏的灵敏度, 以确定在食品的陆来源, 根据局似乎是主要的膳食贡献者在欧洲3。然而, 开发和验证 EN 16278:2012 的同一组测试并成功应用并验证了在协作试验1112中确定海鲜和大米中的 iAs 的方法。
联合研究中心 (JRC) 最近在一个合作试验13中验证了在食品基质中选择性提取 ias 为氯仿和进一步量化的方法。该方法的选择性优于直接 HG 原子吸收光谱法, 易于实现不需要采用 HPLC-电感耦合等离子体质谱仪等精密仪器。在这份手稿中, 使用这种方法的可行性, 以确定在广泛的食品基质的 iAs: 蔬菜, 谷物, 蘑菇和食物的海洋来源, 已经评估。此外, 还介绍了在 EURL 和 JRC 覆盖多个矩阵的能力测试中使用该方法的实验室的性能。

<table><tbody><tr><td>Deionised water</td><td>Any available</td><td></td><td>18.2 M&amp;Omega; cm</td></tr><tr><td>Concentrated hydrochloric acid (HCl).</td><td>Any available</td><td></td><td>Not less than 37 % m/v,&lt;br/&gt; c(HCl) = 12 mol/L, with a&lt;br/&gt; density of&lt;br/&gt; approx. &amp;rho; (HCl) 1.15 g/L</td></tr><tr><td>Concentrated nitric acid (HNO&lt;sub&gt;3&lt;/sub&gt;)</td><td>Any available</td><td></td><td>Not less that 65 % m/v,&lt;br/&gt; c(HNO3) = 14 mol/L, with a&lt;br/&gt; densitiy of approx.&lt;br/&gt; &amp;rho; 1.38 g/L</td></tr><tr><td>Chloroform</td><td>Any available</td><td></td><td>Harmful by inhalation and if swallowed. Irritating to skin.&lt;br/&gt; Wear suitable protective clothing and gloves.</td></tr><tr><td>Hydrogen bromide (HBr)</td><td>Any available</td><td></td><td>Not less than 48 % m/v</td></tr><tr><td>Hydrazine sulphate (N&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;6&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;)</td><td>Any available</td><td></td><td>Harmful if swallowed.&lt;br/&gt; Causes burns.&lt;br/&gt; May cause cancer.</td></tr><tr><td>Magnesium nitrate hexahydrate [Mg(NO&lt;sub&gt;3&lt;/sub&gt;)6H&lt;sub&gt;2&lt;/sub&gt;O]</td><td>Any available</td><td></td><td></td></tr><tr><td>Magnesium oxide (MgO)</td><td>Any available</td><td></td><td></td></tr><tr><td>Potassium iodide (KI)</td><td>Any available</td><td></td><td></td></tr><tr><td>Ascorbic acid (C&lt;sub&gt;6&lt;/sub&gt;H&lt;sub&gt;8&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt;)</td><td>Any available</td><td></td><td></td></tr><tr><td>Sodium hydroxide (NaOH)</td><td>Any available</td><td></td><td></td></tr><tr><td>Sodium borohydride (NaBH&lt;sub&gt;4&lt;/sub&gt;)</td><td>Any available</td><td></td><td></td></tr><tr><td>Arsenic (V) standard solution</td><td>Any available</td><td></td><td>1,000 mg/L&lt;br/&gt; Use certified standard&lt;br/&gt; solutions commercially available</td></tr><tr><td>Centrifuge</td><td>Any available</td><td></td><td></td></tr><tr><td>Mechanical shaker</td><td>Any available</td><td></td><td></td></tr><tr><td>Sand bath</td><td>Any available</td><td></td><td></td></tr><tr><td>Muffle furnace</td><td>Any available</td><td></td><td></td></tr><tr><td>Polypropylene centrifuge (PC) tubes</td><td>Any available</td><td></td><td>50 mL with screw cap</td></tr><tr><td>Syringe filters with hydrophobic PTFE membrane</td><td>Any available</td><td></td><td>25 mm diameter</td></tr><tr><td>Pyrex glass beaker</td><td>Any available</td><td></td><td>Tall form 250 mL,&lt;br/&gt; capable of withstanding 500 &amp;deg;C</td></tr><tr><td>Watch glasses</td><td>Any available</td><td></td><td></td></tr><tr><td>Volumetric flasks</td><td>Any available</td><td></td><td>10, 25, 100 or 200,&lt;br/&gt; Class A.</td></tr><tr><td>Plastic funnels</td><td>Any available</td><td></td><td></td></tr><tr><td>Whatman n&amp;deg; 1 paper or equivalent</td><td>Any available</td><td></td><td></td></tr><tr><td>Atomic absorption spectrometer equipped with a flow injection system (FI-AAS)</td><td>Any available</td><td></td><td></td></tr></tbody></table>

determination of inorganic arsenic in a wide range of food matrices using hydride generation - atomic absorption spectrometry.

欧洲食品安全局 (局) 在其关于食品中砷的科学观点中强调, 为了支持通过饮食对无机砷进行可靠的暴露评估, 关于各种食品类型中砷种类分布的信息必须生成.先前在合作试验中证实的一种方法已被应用于多种食品基质中的无机砷的测定, 包括谷物、蘑菇和海洋来源的食物 (总共31样本)。该方法是以流动注射-氢化物发生-原子吸收光谱法在浓缩 HCl 中的蛋白质消化后, 选择性地提取到氯仿中进行检测。该方法的特点是定量的10µg/千克干重, 允许定量的无机砷在大量的食品基质。提供的资料是关于该方法所取得的成绩的成绩, 并由不同的实验室在几项能力测试中报告。用所讨论的方法获得的满意结果的百分比高于其他分析法的结果。

采用该方法确定了从不同的西班牙市场购买的几种食品中的 iAs 质量分数。该方法为一系列不同的矩阵所得到的结果被归类在表 4中, 按照局3所使用的类别, 在该报告中, 对欧洲人口中的无机砷进行膳食接触评估官方控制实验室 (OCL) 报告的数据基础。在表 4中的结果表示对不同食品类别的重复性标准偏差 (SR) 的平均值为三复制±, 在协作试验中计算了当前方法的有效性13。表 4中显示的结果与以前在类似矩阵中发布的其他11、12、14有很好的一致性。
特别重要的是, 在不同类型的大米中获得了 iAs 的结果, 因为在欧洲的食品污染物立法中, 对它们的最大限制是1。与 OCLs3的结果一致, 糙米的最高值和白米最低。发现的最高水平为海草羊菜, 它的消耗量由几个当局劝阻了, 如报告中所示的局。
参加 EURL-HM 和 JRC 组织的临时技术研究所和使用这种方法确定国际会计准则的实验室的表现, 与使用其他方法的实验室的性能进行了比较。大多数其他方法是基于 HPLC-电感耦合等离子体质谱 (约50% 的评价结果) 和汞原子吸收光谱法与其他砷种 (25% 的总),图 1。使用的其他方法 (约15% 的评价结果), 是基于电热雾化 (ETAAS), 荧光检测和 icp 耦合原子发射光谱 (icp-aes), 有和没有氢化物发生, 并一起评估在 "其他方法" 的名义下, 因为个别数字太少而没有任何统计意义。
使用该评价方法的一些实验室介绍了原始协议的一些变体, 并采用了电感耦合等离子体质谱代替了原子吸收光谱法。这些实验室通常没有应用干灰化步骤 (协议中的步骤 5), 只是将1米 HCl 阶段引入了 ICP-MS。评估涵盖了各种矩阵: 大米15,16, 小麦, 菠菜, 藻类17和巧克力18。
实验室表现为 z 评分: 
<img alt="Equation 2" src="/files/ftp_upload/55953/55953eq2.jpg"> 在: xlab是 PT 中参与者报告的测量结果 Xref是分配的值 (用于基准实验室)。在本文件所述的所有分项中, 由一组专家实验室在 iAs 分析领域使用不同的分析方法建立了分配的价值。 σ是标准偏差为能力评估, 固定由 PT 提供者考虑到艺术的状态在某一区域分析。在本文所考虑的, σ是15% 的分配值大米和小麦, 22% 的藻类和25% 的菠菜和巧克力。
z 评分的解释是根据 ISO 17043:201019进行的: | 分数 |≤2令人满意的性能 2和 #60; | 评分 |和 #60; 3 可疑 (Q) 性能 | 分数 |≥ 3 (U) 性能不佳
七十五的结果与上述方法得到了满意的 z 评分。在考虑到海洋来源基质中砷种类的复杂分布的情况下, 测定藻类中的 iAs 质量分数是有挑战性的。利用这种方法, 在 IMEP-112 中报告的三值中, 有两个是不令人满意的 z 评分。在其他方法的结果中也发现了同样的困难。除去藻类中的 iAs 报告的结果, 85% 的结果与评价方法是令人满意的。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55953/55953fig1.jpg"> 
图 1:IMEP-107、IMEP-112、EURL-HM-20 和 IRMM-PT-43) 的实验室性能 (以 z 评分表示) 与本文介绍的方法以及其他常用方法的比较.谢: 令人满意, Q: 值得怀疑和 U: 不满意。<a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55953/55953fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td></td>
			<td>预期的 iAs 质量分数 低于0.010 毫克/千克</td>
			<td>预期的 iAs 质量分数 高于所覆盖的范围 由定标曲线</td>
		</tr>
		<tr>
			<td>6摩尔 L-1 盐酸体积用于溶解骨灰 (毫升)</td>
			<td>2</td>
			<td>10</td>
		</tr>
		<tr>
			<td>预还原剂容积 (毫升)</td>
			<td>2</td>
			<td>10</td>
		</tr>
		<tr>
			<td>最终卷 (mL)</td>
			<td>10</td>
			<td>50</td>
		</tr>
	</tbody>
</table>
表 1: 在分析预期非常低或非常高的 iAs 浓度的样本时对协议进行的修改。
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>集中在 校准曲线 (µg/升)</td>
			<td>分 (毫升)</td>
		</tr>
		<tr>
			<td>0。5</td>
			<td>1</td>
		</tr>
		<tr>
			<td>1</td>
			<td>2 (QC1)</td>
		</tr>
		<tr>
			<td>2。5</td>
			<td>5</td>
		</tr>
		<tr>
			<td>5</td>
			<td>10 (QC2)</td>
		</tr>
		<tr>
			<td>7。5</td>
			<td>15</td>
		</tr>
		<tr>
			<td>10</td>
			<td>20</td>
		</tr>
		<tr>
			<td colspan="2">所有作为 (III) 校准标准解决方案应在每次校准前准备就绪。</td>
		</tr>
	</tbody>
</table>
表 2:等分从25µg/升为 (V) 标准解决方案, 以在50毫升的最终体积中构造 As (III) 校准曲线.
<table border="1" border="1"></table border="1" >佛: 保持在一起. 在页内 = "1" fo: 保持-与-下. 页内 = "始终" ><tbody>
		<tr>
			<td rowspan="4">流动注射 氢化物产生</td>
			<td>·        循环采样: 0.5 毫升 (当最终 pre-reducing 溶液的重构体积与25毫升不同时, 可进行调整)。</td>
		</tr>
		<tr>
			<td>·        还原剂: 0.2% (w/v) NaBH4在 0.05% (w/v) 氢氧化钠中;5毫升/分钟流量。</td>
		</tr>
		<tr>
			<td>·        HCl 溶液 10% (v/v), 10 毫升/分钟流量。</td>
		</tr>
		<tr>
			<td>·        载体气体: 氩, 100 毫升/分钟流量。</td>
		</tr>
		<tr>
			<td rowspan="5">原子吸收 光谱仪</td>
			<td>·        波长: 193.7 nm</td>
		</tr>
		<tr>
			<td>·        光谱带通: 0.7 毫微米</td>
		</tr>
		<tr>
			<td>·        无极放电灯系统2</td>
		</tr>
		<tr>
			<td>·        灯具电流设置: 400 毫安</td>
		</tr>
		<tr>
			<td>·        电池温度: 900 ° c</td>
		</tr>
	</tbody>

表 3:利用汞原子吸收光谱法对 iAs 进行量化的仪器条件
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="2">食物</td>
			<td>i-作为 (µg/公斤新的重量)</td>
		</tr>
		<tr>
			<td>谷物和谷物产品</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>水稻</td>
			<td>白色</td>
			<td>113±18</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>73±12</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>56±9</td>
		</tr>
		<tr>
			<td></td>
			<td>棕色</td>
			<td>197±32</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>125±20</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>275±44</td>
		</tr>
		<tr>
			<td></td>
			<td>谷米</td>
			<td>134±21</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>159±25</td>
		</tr>
		<tr>
			<td></td>
			<td>圆</td>
			<td>162±26</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>127±20</td>
		</tr>
		<tr>
			<td>蔬菜和蔬菜产品</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>脱水蘑菇</td>
			<td>牛果</td>
			<td>174±10</td>
		</tr>
		<tr>
			<td></td>
			<td>Galocybe gambosa</td>
			<td>74±4</td>
		</tr>
		<tr>
			<td></td>
			<td>伞 oreades</td>
			<td>104±6</td>
		</tr>
		<tr>
			<td></td>
			<td>鸡 lutescens</td>
			<td>16±1</td>
		</tr>
		<tr>
			<td></td>
			<td>香菇</td>
			<td>96±6</td>
		</tr>
		<tr>
			<td>海草</td>
			<td>羊菜</td>
			<td>97000±14550</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>44943±6742</td>
		</tr>
		<tr>
			<td></td>
			<td>藻 vesiculosus</td>
			<td>288±43</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>433±65</td>
		</tr>
		<tr>
			<td>鱼和其他海鲜</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>鱼肉</td>
			<td>平头乌鱼</td>
			<td>53±12</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>21±5</td>
		</tr>
		<tr>
			<td></td>
			<td>欧洲鳗鱼</td>
			<td>72±16</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>42±9</td>
		</tr>
		<tr>
			<td></td>
			<td>龙虾</td>
			<td>33±7</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>20±4</td>
		</tr>
		<tr>
			<td></td>
			<td>金枪鱼</td>
			<td>11±2</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>5±1</td>
		</tr>
		<tr>
			<td>软体动物</td>
			<td>蛤</td>
			<td>243±54</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>133±29</td>
		</tr>
		<tr>
			<td></td>
			<td>贻</td>
			<td>32±32</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>139±31</td>
		</tr>
	</tbody>
</table>
表 4: 应用所述方法得到的一系列不同矩阵的结果。

Watch this Scientific Journal Video about Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry. at JoVE.com

Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry.

论证了一种分析方法在广泛的食品基质中测定无机砷的有效性。该方法由氢化物发生-原子吸收光谱法进行最终测定, 将无机砷选择性萃取到氯仿中。

用氢化物发生-原子吸收光谱法测定多种食品基质中的无机砷。

The European Food Safety Authority (EFSA) underlined in its Scientific Opinion on Arsenic in Food that in order to support a sound exposure assessment to ...

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14.6K 次观看.  Joint Research Centre. 论证了一种分析方法在广泛的食品基质中测定无机砷的有效性。该方法由氢化物发生-原子吸收光谱法进行最终测定, 将无机砷选择性萃取到氯仿中。

视频: Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry.

Quantification of Heavy Metals and Other Inorganic Contaminants on the Productivity of Microalgae

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages include high potential yield, use of non-arable land and integration with waste streams. The nutrient requirements of a large-scale microalgae production system will require the coupling of cultivation systems with industrial waste resources, such as carbon dioxide from flue gas and nutrients from wastewater. Inorganic contaminants present in these wastes can potentially lead to bioaccumulation in microalgal biomass negatively impact productivity and limiting end use. This study focuses on the experimental evaluation of the impact and the fate of 14 inorganic contaminants (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V and Zn) on Nannochloropsis salina growth. Microalgae were cultivated in photobioreactors illuminated at 984 &#181;mol m-2 sec-1 and maintained at pH 7 in a growth media polluted with inorganic contaminants at levels expected based on the composition found in commercial coal flue gas systems. Contaminants present in the biomass and the medium at the end of a 7 day growth period were analytically quantified through cold vapor atomic absorption spectrometry for Hg and through inductively coupled plasma mass spectrometry for As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, V and Zn. Results show N. salina is a sensitive strain to the multi-metal environment with a statistical decrease in biomass yieldwith the introduction of these contaminants. The techniques presented here are adequate for quantifying algal growth and determining the fate of inorganic contaminants.

Integration of microalgal cultivation with industrial flue gas will ultimately introduce heavy metals and other inorganic compounds into the growth media. This study presents a procedure used to determine the end fate and impact of heavy metals and inorganic contaminants on the growth of Nannochloropsis salina grown in photobioreactors.

重金属和微藻的产其他无机污染物的量化

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages ...

科研

环境科学

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron (Oxy)Hydroxides, Trace Elements, and Bacteria

Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as redox potential (Eh) and pH, but also to microbial activities that can play a direct or indirect role on speciation and/or mobility. Indeed, some bacteria can directly oxidize As(III) to As(V) or reduce As(V) to As(III). Likewise, bacteria are strongly involved in Hg cycling, either through its methylation, forming the neurotoxin monomethyl mercury, or through its reduction to elemental Hg&#176;. The fates of both As and Hg are also strongly linked to soil or aquifer composition; indeed, As and Hg can bind to organic compounds or (oxy)hydroxides, which will influence their mobility. In turn, bacterial activities such as iron (oxy)hydroxide reduction or organic matter mineralization can indirectly influence As and Hg sequestration. The presence of sulfate/sulfide can also strongly impact these particular elements through the formation of complexes such as thio-arsenates with As or metacinnabar with Hg.
Consequently, many important questions have been raised on the fate and speciation of As and Hg in the environment and how to limit their toxicity. However, due to their reactivity towards aquifer components, it is difficult to clearly dissociate the biogeochemical processes that occur and their different impacts on the fate of these TE.
To do so, we developed an original, experimental, column setup that mimics an aquifer with As- or Hg-iron-oxide rich areas versus iron depleted areas, enabling a better understanding of TE biogeochemistry in anoxic conditions. The following protocol gives step by step instructions for the column set-up either for As or Hg, as well as an example with As under iron and sulfate reducing conditions.

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron OxyHydroxides, Trace Elements, and Bacteria

Fate and speciation of arsenic and mercury in aquifers are closely related to physio-chemical conditions and microbial activity. Here, we present an original experimental column setup that mimics an aquifer and enables a better understanding of trace element biogeochemistry in anoxic conditions. Two examples are presented, combining geochemical and microbiological approaches.

用于研究铁 (氧) 氢氧化物、微量元素和细菌之间厌氧生物地球化学相互作用的实验柱装置

Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as ...

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic pathway of dimethylarsinic acid (DMAV) thiolation, have been recently found in the environment as well as human organs. DMMTAV and DMDTAV can be quantified to determine the ecological effects of dimethylated thioarsenicals and their stability in environmental media. The synthesis method for these compounds is unstandardized, making replicating previous studies challenging. Furthermore, there is a lack of information about storage techniques, including storage of compounds without species transformation. Moreover, because only limited information about synthesis methods is available, there may be experimental difficulties in synthesizing standard chemicals and performing quantitative analysis. The protocol presented herein provides a practically modified synthesis method for the dimethylated thioarsenicals, DMMTAV and DMDTAV, and will help in the quantification of species separation analysis using high performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The experimental steps of this procedure were modified by focusing on the preparation of chemical reagents, filtration methods, and storage.

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

This article presents modified experimental protocols for dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV) synthesis, inducing dimethylarsinic acid (DMAV) thiolation through mixing of DMAV, Na2S, and H2SO4. The modified protocol provides an experimental guideline, thereby overcoming limitations of the synthesis steps that could have caused experimental failures in quantitative analysis.

使用 DMAv为环境应用 DMMTAv和 DMDTAv的准备: 合成、纯化和确认

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic ...

Removal of Arsenic Using a Cationic Polymer Gel Impregnated with Iron Hydroxide

In this work, we prepared an adsorbent composed of a cationic polymer gel containing iron hydroxide in its structure designed to adsorb arsenic from groundwater. The gel we selected was the N,N-dimethylamino propylacrylamide methyl chloride quaternary (DMAPAAQ) gel. The objective of our preparation method was to ensure the maximum content of iron hydroxide in the structure of the gel. This design approach enabled simultaneous adsorption by both the polymer structure of the gel and the iron hydroxide component, thus, enhancing the adsorption capacity of the material. To examine the performance of the gel, we measured reaction kinetics, carried out pH sensitivity and selectivity analyses, monitored arsenic adsorption performance, and conducted regeneration experiments. We determined that the gel undergoes a chemisorption process and reaches equilibrium at 10 h. Moreover, the gel adsorbed arsenic effectively at neutral pH levels and selectively in complex ion environments, achieving a maximum adsorption volume of 1.63 mM/g. The gel could be regenerated with 87.6% efficiency and NaCl could be used for desorption instead of harmful NaOH. Taken together, the presented gel-based design method is an effective approach for constructing high-performance arsenic adsorbents.

In this work, we prepared an adsorbent composed of the cationic N,N-dimethylamino propylacrylamide methyl chloride quaternary (DMAPAAQ) polymer gel and iron hydroxide for adsorbing arsenic from groundwater. The gel was prepared via a novel method designed to ensure the maximum content of iron particles in its structure.

去除砷使用阳离子聚合物凝胶浸渍与氢氧化铁

In this work, we prepared an adsorbent composed of a cationic polymer gel containing iron hydroxide in its structure designed to adsorb arsenic from ...

Atomic Absorbance Spectroscopy to Measure Intracellular Zinc Pools in Mammalian Cells

Transition metals are essential micronutrients for organisms but can be toxic to cells at high concentrations by competing with physiological metals in proteins and generating redox stress. Pathological conditions that lead to metal depletion or accumulation are causal agents of different human diseases. Some examples include anemia, acrodermatitis enteropathica, and Wilson&#8217;s and Menkes&#8217; diseases. It is therefore important to be able to measure the levels and transport of transition metals in biological samples with high sensitivity and accuracy in order to facilitate research exploring how these elements contribute to normal physiological functions and toxicity. Zinc (Zn), for example, is a cofactor in many mammalian proteins, participates in signaling events, and is a secondary messenger in cells. In excess, Zn is toxic and can inhibit absorption of other metals, while in deficit, it can lead to a variety of potentially lethal conditions.

Graphite furnace atomic absorption spectroscopy (GF-AAS) provides a highly sensitive and effective method for determining Zn and other transition metal concentrations in diverse biological samples. Electrothermal atomization via GF-AAS quantifies metals by atomizing small volumes of samples for subsequent selective absorption analysis using wavelength of excitation of the element of interest. Within the limits of linearity of the Beer-Lambert Law, the absorbance of light by the metal is directly proportional to concentration of the analyte. Compared to other methods of determining Zn content, GF-AAS detects both free and complexed Zn in proteins and possibly in small intracellular molecules with high sensitivity in small sample volumes. Moreover, GF-AAS is also more readily accessible than inductively coupled plasma mass spectrometry (ICP-MS) or synchrotron-based X-ray fluorescence. In this method, the systematic sample preparation of different cultured cell lines for analyses in a GF-AAS is described. Variations in this trace element were compared in both whole cell lysates and subcellular fractions of proliferating and differentiated cells as proof of principle.

Cultured primary or established cell lines are commonly used to address fundamental biological and mechanistic questions as an initial approach before using animal models. This protocol describes how to prepare whole cell extracts and subcellular fractions for studies of zinc (Zn) and other trace elements with atomic absorbance spectroscopy.

原子吸纳光谱测量哺乳动物细胞细胞内锌池

Transition metals are essential micronutrients for organisms but can be toxic to cells at high concentrations by competing with physiological metals in ...

生物化学

Quantification of Humic and Fulvic Acids in Humate Ores, DOC, Humified Materials and Humic Substance-Containing Commercial Products

The purpose of this method is to provide an accurate and precise concentration of humic (HA) and/or fulvic acids (FA) in soft coals, humic ores and shales, peats, composts and humic substance-containing commercial products. The method is based on the alkaline extraction of test materials, using 0.1 N NaOH as an extractant, and separation of the alkaline soluble humic substances (HS) from nonsoluble products by centrifugation. The pH of the centrifuged alkaline extract is then adjusted to pH 1 with conc. HCl, which results in precipitation of the HA. The precipitated HA are separated from the fulvic fraction (FF) (the fraction of HS that remains in solution,) by centrifugation. The HA is then oven or freeze dried and the ash content of the dried HA determined. The weight of the pure (i.e., ash-free) HA is then divided by the weight of the sample and the resulting fraction multiplied by 100 to determine the % HA in the sample. To determine the FA content, the FF is loaded onto a hydrophobic DAX-8 resin, which adsorbs the FA fraction also referred to as the hydrophobic fulvic acid (HFA). The remaining non-fulvic acid fraction, also called the hydrophilic fulvic fraction (HyFF) is then removed by washing the resin with deionized H2O until all nonabsorbed material is completely removed. The FA is then desorbed with 0.1 N NaOH. The resulting Na-fulvate is then protonated by passing it over a strong H+-exchange resin. The resulting FA is oven or freeze dried, the ash content determined and the concentration in the sample calculated as described above for HA.

This method provides a gravimetric quantification of humic substances (e.g., humic and fulvic acids) on an ash-free basis, in dry and liquid materials from soft coals (i.e., oxidized and non-oxidized lignite and sub-bituminous coal), humate ores and shales, peats, composts and commercial fertilizers and soil amendments.

腐植酸盐矿石、DOC、腐殖化材料和含腐殖质的商业产品中腐殖酸和黄腐酸的定量

The purpose of this method is to provide an accurate and precise concentration of humic (HA) and/or fulvic acids (FA) in soft coals, humic ores and ...

Biological Samples Preparation for Speciation at Cryogenic Temperature using High-Resolution  X-Ray Absorption Spectroscopy

The study of elements with X-ray absorption spectroscopy (XAS) is of particular interest when studying the role of metals in biological systems. Sample preparation is a key and often complex procedure, particularly for biological samples. Although X-ray speciation techniques are widely used, no detailed protocol has been yet disseminated for users of the technique. Further, chemical state modification is of concern, and cryo-based techniques are recommended to analyze the biological samples in their near-native hydrated state to provide the maximum preservation of chemical integrity of the cells or tissues. Here, we propose a cellular preparation protocol based on cryo-preserved samples. It is demonstrated in a high energy resolution fluorescence detected X-ray absorption spectroscopy study of selenium in cancer cells and a study of iron in phytoplankton. This protocol can be used with other biological samples and other X-ray techniques that can be damaged by irradiation.

This protocol presents a detailed procedure to prepare biological cryosamples for synchrotron-based X-ray absorption spectroscopy experiments. We describe all the steps required to optimize sample preparation and cryopreservation with examples of the protocol with cancer and phytoplankton cells. This method provides a universal standard of sample cryo-preparation.

使用高分辨率X射线吸收光谱在低温下制备生物样品以进行形态分析

The study of elements with X-ray absorption spectroscopy (XAS) is of particular interest when studying the role of metals in biological systems. Sample ...

化学

用于多元素分析的食品样品均质化和消解

Preparation of Food Samples Using Homogenization and Microwave-Assisted Wet Acid Digestion for Multi-Element Determination with ICP-MS

Sample preparation is crucial for elemental determination, and various techniques are available, one of which involves homogenization followed by acid digestion. Special care is required during sample handling in the preparation stage to eliminate or minimize potential contamination and analyte loss. Homogenization is a process that simultaneously reduces particle size and uniformly distributes sample components. Following homogenization, the sample undergoes acid digestion, wherein it is digested with acids and auxiliary chemicals at elevated temperatures, transforming solid samples into a liquid state. In this process, metals in the original sample react with acids to form water-soluble salts. Samples prepared through acid digestion are suitable for elemental analysis using techniques such as inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectroscopy, atomic absorption spectroscopy, electrochemical methods, and other analytical techniques. This work details the preparation of food samples for multi-element determination using inductively coupled plasma mass spectrometry. The step-by-step procedure involves the homogenization process using a laboratory-sized mixer with ceramic blades, followed by acid digestion in closed vessels using microwave-assisted wet acid digestion. A mixture of 5.0 mL of 68 wt% HNO3 and 1.0 mL of 30 wt% H2O2 serves as an auxiliary reagent. This guide provides an explanation of the processes involved in both stages.

作者聚焦：食品样品元素分析的技术和挑战

The presented protocol describes sample homogenization with a laboratory mixer, acid digestion of food samples using a mixture of 68 wt% HNO3 and 30 wt% H2O2&#160;via microwave-assisted wet acid digestion, and multi-element determination performed with inductively coupled plasma mass spectrometry.

使用均质化和微波辅助湿酸消解制备食品样品，用于ICP-MS多元素测定

Sample preparation is crucial for elemental determination, and various techniques are available, one of which involves homogenization followed by acid ...

用氢化物发生-原子吸收光谱法测定多种食品基质中的无机砷。

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此视频中的章节

重金属和微藻的产其他无机污染物的量化

用于研究铁 (氧) 氢氧化物、微量元素和细菌之间厌氧生物地球化学相互作用的实验柱装置

使用 DMA^v为环境应用 DMMTA^v和 DMDTA^v的准备: 合成、纯化和确认

去除砷使用阳离子聚合物凝胶浸渍与氢氧化铁

原子吸纳光谱测量哺乳动物细胞细胞内锌池

腐植酸盐矿石、DOC、腐殖化材料和含腐殖质的商业产品中腐殖酸和黄腐酸的定量

使用高分辨率X射线吸收光谱在低温下制备生物样品以进行形态分析

使用均质化和微波辅助湿酸消解制备食品样品，用于ICP-MS多元素测定

使用均质化和微波辅助湿酸消解制备食品样品，用于ICP-MS多元素测定

使用均质化和微波辅助湿酸消解制备食品样品，用于ICP-MS多元素测定