Department of Chemistry, Izmir Institute of Technology, Gulbahce, Urla 35430, Izmir, Turkey.
Talanta. 2010 Jan 15;80(3):1452-60. doi: 10.1016/j.talanta.2009.09.053.
A natural biosorbent containing amine functional groups, chitosan, and a novel sorbent, chitosan-immobilized sodium silicate, were prepared and utilized for the selective sorption of As(V) from waters prior to its determination by atomic spectrometric techniques, namely, hydride generation atomic absorption spectrometry (HGAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Chitosan was synthesized from chitin and sodium silicate was used as the immobilization matrix due to its straightforward synthesis. Through sequential sorption studies, it was shown that chitosan-immobilized sodium silicate has exhibited a better chemical stability than the chitosan itself which demonstrates the advantage of immobilization method. Both chitosan and chitosan-immobilized sodium silicate were shown to selectively adsorb As(V), arsenate, from waters at pH 3.0 at which neither chitin nor sodium silicate displayed any sorption towards As(V). The sorption of arsenate by chitosan is supposed to have electrostatic nature since pH of 3.0 is both the point at which the amino groups in chitosan are protonated and also the predominant form of As(V) is H(2)AsO(4)(-). A pre-oxidation step is required if both As(III) and As(V) are to be determined. Desorption from the sorbents was realized with 1.0% (w/v) l-cysteine prepared in a pH 3.0 solution adjusted with HCl. Among the possible interfering species tested, only Te(IV) and Sb(III) were shown to cause a decrease in the sorption capacity especially at high interferant concentrations. High concentrations of Sb(III) also resulted in gas phase interference during hydride generation. The validity of the method was checked both via spike recovery experiments and also through the analysis of a standard reference material. Spike recovery tests were carried out with four different types of water; namely, ultra-pure, bottled drinking, tap, and sea water; and percent recovery values were found to be 114 (+/-4), 112 (+/-2), 43 (+/-4), and 0 (+/-1), respectively. It was concluded that the proposed methodology can be applied efficiently to low-to-medium ionic strength solutions, such as most drinking waters. The accuracy of the method was additionally investigated through the analysis of a standard reference material and a good correlation was found between the determined (26.6+/-2.4microgL(-1)) and the certified (26.67microgL(-1)) value.
一种含有胺基官能团的天然生物吸附剂壳聚糖和一种新型吸附剂壳聚糖固定化硅酸钠，被制备并用于在原子光谱技术（即氢化物发生原子吸收光谱法（HGAAS）和电感耦合等离子体质谱法（ICP-MS））测定砷（V）之前，从水中选择性地吸附砷（V）。壳聚糖是由几丁质合成的，硅酸钠被用作固定化基质，因为它的合成方法简单。通过顺序吸附研究表明，壳聚糖固定化硅酸钠比壳聚糖本身具有更好的化学稳定性，这证明了固定化方法的优势。壳聚糖和壳聚糖固定化硅酸钠都被证明可以在 pH 3.0 下从水中选择性地吸附砷（V），即砷酸盐，而几丁质和硅酸钠都没有表现出对砷（V）的任何吸附。壳聚糖对砷酸盐的吸附可能具有静电性质，因为 pH 3.0 是壳聚糖中氨基质子化的点，也是砷（V）的主要形式 H（2）AsO（4）（-）。如果要同时测定砷（III）和砷（V），则需要进行预氧化步骤。用在 pH 3.0 溶液中用 HCl 调节的 1.0%（w/v）L-半胱氨酸从吸附剂上解吸。在所测试的可能干扰物质中，只有 Te（IV）和 Sb（III）被证明会降低吸附容量，特别是在高干扰物质浓度下。高浓度的 Sb（III）也会导致氢化物生成过程中的气相干扰。该方法的有效性通过加标回收实验和对标准参考物质的分析进行了检查。加标回收实验用四种不同类型的水进行，即超纯水、瓶装饮用水、自来水和海水，回收率分别为 114（+/-4）、112（+/-2）、43（+/-4）和 0（+/-1）。结果表明，该方法可以有效地应用于低至中等离子强度的溶液，如大多数饮用水。该方法的准确性还通过对标准参考物质的分析进行了研究，发现测定值（26.6+/-2.4microgL（-1））与认证值（26.67microgL（-1））之间存在良好的相关性。
