Department of Chemistry, Faculty of Sciences, Azarbaijan Shahid Madani University, 35 Km Tabriz-Marageh Road, P.O. Box 53714-161, Tabriz, Iran.
Talanta. 2013 Nov 15;116:604-10. doi: 10.1016/j.talanta.2013.07.040. Epub 2013 Jul 26.
A selective solid phase extraction method, based on nano-structured Mg-Al-Fe(NO3(-)) ternary layered double hydroxide as a sorbent, is developed for the pre-concentration of ultra-trace levels of arsenic (As) prior to determination by electrothermal atomic absorption spectrometry. It is found that both As(III) and As(V) could be quantitatively retained on the sorbent within a wide pH range of 4-12. Accordingly, the presented method is applied to determination of total inorganic As in aqueous solutions. Maximum analytical signal of As is achieved when the pyrolysis and atomization temperatures are close to 900 °C and 2300 °C, respectively. Several variables affecting the extraction efficiency including pH, sample flow rate, amount of nano-sorbent, elution conditions and sample volume are optimized. Under the optimized conditions, the limit of detection (3Sb/m) and the relative standard deviation are 4.6 pg mL(-1) and 3.9%, respectively. The calibration graph is linear in the range of 15.0-650 pg mL(-1) with a correlation coefficient of 0.9979, sorption capacity and pre-concentration factor are 8.68 mg g(-1) and 300, respectively. The developed method is validated by the analysis of a standard reference material (SRM 1643e) and is successfully applied to the determination of ultra-trace amounts of As in different water samples.
一种基于纳米结构的 Mg-Al-Fe(NO3(-))三元层状双氢氧化物作为吸附剂的选择性固相萃取方法，用于电加热原子吸收光谱法测定前超痕量砷（As）的预浓缩。结果表明，在 pH 值为 4-12 的较宽范围内，As(III)和 As(V)均可定量保留在吸附剂上。因此，该方法可用于测定水溶液中的总无机 As。当热解和原子化温度分别接近 900°C 和 2300°C 时，As 的分析信号最大。优化了影响萃取效率的几个变量，包括 pH 值、样品流速、纳米吸附剂用量、洗脱条件和样品体积。在优化条件下，检测限（3Sb/m）和相对标准偏差分别为 4.6 pg mL(-1)和 3.9%。校准曲线在 15.0-650 pg mL(-1)范围内呈线性，相关系数为 0.9979，吸附容量和预浓缩因子分别为 8.68 mg g(-1)和 300。该方法通过对标准参考物质（SRM 1643e）的分析进行了验证，并成功应用于不同水样中超痕量 As 的测定。
