Sun Y C, Chang Y C, Su C K
Development of Biomedical Engineering and Environmental Sciences and Nuclear Science and Technology Development Center, National Tsing-Hua University, 30043 Hsinchu, Taiwan.
Anal Chem. 2006 Apr 15;78(8):2640-5. doi: 10.1021/ac051899b.
We have developed an UV/nano-TiO2 vapor generation (VG) device that when coupled between a chromatographic column and an ICP mass spectrometer provides a simple and sensitive hyphenated method for the determination of Se(IV) and Se(VI) without the need to use conventional chemical VG techniques. Because our proposed VG device allows both Se(IV) and Se(VI) species in the column effluent to be converted on-line into volatile Se products, which are then measured directly by the ICPMS, the safety risks and the probability of contamination arising from the use of additional chemicals are both low. To achieve the maximum signal intensity, we optimized a number of the operating parameters of the UV/nano-TiO2 VG device, including the acidity, the amounts of TiO2 and formic acid, and the length of the reaction coil, with respect to their effects on the reduction efficiency of the analyte species. This hyphenated method achieves excellent detection limits-0.06 and 0.03 ng mL(-1) for Se(IV) and Se(VI), respectively-because of the high efficiencies of the conversions of Se(IV) and Se(VI) to their respective volatile products and the lower blank level achieved, relative to those of other traditional systems. In addition, because the conversion efficiency of the analyte selenium species reached its maximum level within 36 s of irradiation, the working time (approximately 12 min) was limited primarily by time required for the chromatographic separation. A series of validation experiments-analysis of the 1643e Standard Reference Material and natural water samples-indicated that our proposed methods can be applied satisfactorily to the determination of inorganic selenium species in water samples.
我们开发了一种紫外/纳米二氧化钛蒸气发生（VG）装置，该装置连接在色谱柱和电感耦合等离子体质谱仪之间，提供了一种简单且灵敏的联用方法，用于测定Se(IV)和Se(VI)，无需使用传统的化学蒸气发生技术。由于我们提出的VG装置可使柱流出物中的Se(IV)和Se(VI)物种在线转化为挥发性硒产物，然后直接由电感耦合等离子体质谱仪进行测量，因此使用额外化学品带来的安全风险和污染概率都很低。为了实现最大信号强度，我们针对紫外/纳米二氧化钛VG装置的一些操作参数进行了优化，包括酸度、二氧化钛和甲酸的用量以及反应盘管的长度，考察了它们对分析物物种还原效率的影响。这种联用方法实现了出色的检测限，Se(IV)和Se(VI)的检测限分别为0.06和0.03 ng mL⁻¹，这是因为Se(IV)和Se(VI)分别转化为各自挥发性产物的效率很高，且相对于其他传统系统，空白水平更低。此外，由于分析物硒物种的转化效率在照射36秒内达到最高水平，工作时间（约12分钟）主要受色谱分离所需时间的限制。一系列验证实验——对1643e标准参考物质和天然水样的分析——表明，我们提出的方法可令人满意地应用于水样中无机硒物种的测定。
