Bianchin Joyce Nunes, Martendal Edmar, Mior Renata, Alves Vanessa Nunes, Araújo Cleide Sandra Tavares, Coelho Nívia Maria Melo, Carasek Eduardo
Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis 88040900, SC, Brazil.
Talanta. 2009 Apr 30;78(2):333-6. doi: 10.1016/j.talanta.2008.11.012. Epub 2008 Nov 21.
In this study a method for the determination of cadmium in fuel alcohol using solid-phase extraction with a flow injection analysis system and detection by flame atomic absorption spectrometry was developed. The sorbent material used was a vermicompost commonly used as a garden fertilizer. The chemical and flow variables of the on-line preconcentration system were optimized by means of a full factorial design. The selected factors were: sorbent mass, sample pH, buffer concentration and sample flow rate. The optimum extraction conditions were obtained using sample pH in the range of 7.3-8.3 buffered with tris(hydroxymethyl)aminomethane at 50 mmol L(-1), a sample flow rate of 4.5 mL min(-1) and 160 mg of sorbent mass. With the optimized conditions, the preconcentration factor, limit of detection and sample throughput were estimated as 32 (for preconcentration of 10 mL sample), 1.7 microg L(-1) and 20 samples per hour, respectively. The analytical curve was linear from 5 up to at least 50 microg L(-1), with a correlation coefficient of 0.998 and a relative standard deviation of 2.4% (35 microg L(-1), n=7). The developed method was successfully applied to spiked fuel alcohol, and accuracy was assessed through recovery tests, with recovery ranging from 94% to 100%.
本研究开发了一种采用流动注射分析系统进行固相萃取并通过火焰原子吸收光谱法检测燃料乙醇中镉的方法。所使用的吸附材料是一种常用作花园肥料的蚯蚓堆肥。通过全因子设计对在线预浓缩系统的化学和流动变量进行了优化。选定的因素为：吸附剂质量、样品pH值、缓冲液浓度和样品流速。使用50 mmol L(-1)的三（羟甲基）氨基甲烷缓冲、pH值在7.3 - 8.3范围内的样品、4.5 mL min(-1)的样品流速和160 mg的吸附剂质量获得了最佳萃取条件。在优化条件下，预浓缩因子、检测限和样品通量分别估计为32（对于10 mL样品的预浓缩）、1.7 μg L(-1)和每小时20个样品。分析曲线在5至至少50 μg L(-1)范围内呈线性，相关系数为0.998，相对标准偏差为2.4%（35 μg L(-1)，n = 7）。所开发的方法成功应用于加标燃料乙醇，并通过回收率测试评估了准确性，回收率范围为94%至100%。
