Dutra Rosilene L, Maltez Heloisa F, Carasek Eduardo
Universidade Federal de Santa Catarina, Departamento de Química, Florianópolis, Santa Catarina, Brazil.
Talanta. 2006 Apr 15;69(2):488-93. doi: 10.1016/j.talanta.2005.10.019. Epub 2005 Nov 28.
An on-line preconcentration system for zinc determination in 24-h urine, blood plasma and erythrocyte matrices by flame atomic absorption spectrometry (FAAS) was used. This procedure was based on adsorption of Zn(II) ions onto a minicolumn filled with silica gel, chemically modified with niobium(V) oxide (Nb(2)O(5)-SiO(2)). The determination of the optimum conditions for Zn(II) preconcentration was done using two-level full factorial and Doehlert designs. In the optimization procedure, four variables (sample pH, eluent concentration, sample flow rate and eluent flow rate) were investigated. The results obtained from the full factorial design demonstrated that the sample pH and sample flow rate variables, and their interactions, were statistically significant. A Doehlert matrix was used in order to determine the optimum conditions for the sample pH and sample flow rate. The optimized conditions for sample pH and flow rate sampling were 6.6 and 7.1 ml min(-1), respectively, to obtain the maximum Zn(II) preconcentration and determination in the biological samples studied. Parameters of analytical curve, precision, effect of other ions in the proposed system and accuracy were achieved to assess the proposed method. The accuracy was confirmed by analysis of certified reference materials (urine Seronorm Trace Elements) and recovery tests in blood plasma and erythrocyte samples. Detection limit (3sigma/S) of 0.77 microg l(-1), precision (calculated as relative standard deviation) of 1.5% for Zn(II) concentration of 10 microg l(-1) (n=7) and a sampling frequency of 27 samples/h were obtained from the proposed system.
采用一种在线预浓缩系统，通过火焰原子吸收光谱法（FAAS）测定24小时尿液、血浆和红细胞基质中的锌。该方法基于Zn(II)离子吸附到填充有经五氧化二铌（Nb₂O₅ - SiO₂）化学修饰的硅胶的微型柱上。使用二级全因子设计和Doehlert设计确定Zn(II)预浓缩的最佳条件。在优化过程中，研究了四个变量（样品pH值、洗脱液浓度、样品流速和洗脱液流速）。全因子设计得到的结果表明，样品pH值和样品流速变量及其相互作用具有统计学意义。使用Doehlert矩阵确定样品pH值和样品流速的最佳条件。样品pH值和流速采样的优化条件分别为6.6和7.1 ml min⁻¹，以便在所研究的生物样品中获得最大的Zn(II)预浓缩和测定。通过分析分析曲线参数、精密度、所提出系统中其他离子的影响以及准确度来评估所提出的方法。通过分析有证标准物质（尿液Seronorm微量元素）以及血浆和红细胞样品的回收率测试来确认准确度。所提出的系统获得的检测限（3σ/S）为0.77 μg l⁻¹，对于10 μg l⁻¹的Zn(II)浓度，精密度（以相对标准偏差计算）为1.5%（n = 7），采样频率为每小时27个样品。
