Afzali Daryoush, Ghaseminezhad Sima, Taher Mohammad Ali
Research Institute of Environmental Sciences International Center for Science, Nanochemistry Department, High Technology and Environmental Sciences, Kerman, Iran.
J AOAC Int. 2010 Jul-Aug;93(4):1287-92.
Multiwalled carbon nanotubes are attractive as sorbents for SPE because they can be used for enrichment of organic compounds and metal ions at trace levels. In this study, multiwalled carbon nanotubes were oxidized with concentrated HNO3, and then the oxidized multiwalled carbon nanotubes were modified with 5-(4'-dimethylamino-benzyliden)-rhodanine. The modified multiwalled carbon nanotubes were used as a solid sorbent for separation and preconcentration of trace amounts of Au(III) ions. The sorption of Au(III) ions was quantitative in the pH range of 2.0-5.0, whereas quantitative desorption occurred instantaneously with 5.0 mL 2.0 M Na2S2O3. The eluted solution was aspirated directly into the flame for atomic absorption spectrometry. The proposed method resulted in an enrichment factor of 94. The RSD of the method was +/- 1.11% (n=10, 2.0 microg/mL) and the LOD was 0.15 ng/mL. The calibration curve for Au(III) was linear between 0.53 ng/mL and 36.0 microg/mL in the initial solution, with an R2 value of 0.9999. The sorbent capacity of the modified multiwalled carbon nanotubes was 7.3 mg Au(III)/g sorbent. The influences of the experimental parameters, including sample pH, sample flow rate, eluent volume and flow rate, sample volume, and interference of some ions on the recoveries of the Au ions, were investigated. The proposed method was applied for preconcentration and determination of Au in different samples.
多壁碳纳米管作为固相萃取的吸附剂很有吸引力，因为它们可用于富集痕量水平的有机化合物和金属离子。在本研究中，多壁碳纳米管用浓硝酸氧化，然后用5-(4'-二甲基氨基-亚苄基)-罗丹宁对氧化后的多壁碳纳米管进行改性。改性后的多壁碳纳米管用作固体吸附剂，用于分离和预富集痕量Au(III)离子。Au(III)离子在pH 2.0 - 5.0范围内的吸附是定量的，而用5.0 mL 2.0 M Na2S2O3可瞬间实现定量解吸。将洗脱液直接吸入火焰进行原子吸收光谱分析。所提出的方法富集因子为94。该方法的相对标准偏差为±1.11%（n = 10，2.0 μg/mL），检测限为0.15 ng/mL。初始溶液中Au(III)的校准曲线在0.53 ng/mL至36.0 μg/mL之间呈线性，R2值为0.9999。改性多壁碳纳米管的吸附容量为7.3 mg Au(III)/g吸附剂。研究了包括样品pH、样品流速、洗脱液体积和流速、样品体积以及某些离子的干扰等实验参数对Au离子回收率的影响。所提出的方法用于不同样品中Au的预富集和测定。
