Hao Jumin, Han Mei-Juan, Meng Xiaoguang, Weimer Wayne, Wang Qingwu K
Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA; Agiltron Inc., 15 Presidential Way, Woburn, MA 01801, USA.
Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 5;136 Pt C:1593-9. doi: 10.1016/j.saa.2014.10.052. Epub 2014 Oct 24.
Surface-enhanced Raman scattering (SERS) has emerged as one of the most sensitive spectroscopic analysis methods for the detection of environmental contaminants in water, including perchlorate (ClO4(-)). However, as with other commonly used analytical techniques, analysis of realistic environmental samples by SERS presents a challenge due to complex chemical components coexisting in the samples. In this work, we investigated the influence of inorganic anions (particularly oxyanions) on SERS spectra of ClO4(-) using a cationic thiol modified silver nanofilm substrate (Cys-Ag/rCu). The results show that the anions present in the samples did not shift the ClO4(-) characteristic band positions, but did decrease signal intensities due to their competitive binding with the -NH3(+) groups of cationic thiol molecules immobilized on the substrates. The pH changes caused by both the dissociation of H2PO4(-) and the hydrolysis of HCO3(-) may also play a non-negligible role. The selectivity of the Cys-Ag/rCu substrate towards these anions was determined to be in the following order: ClO4(-)>SO4(2-)>HCO3(-), NO3(-)>Cl(-)>H2PO4(-), indicating preferential adsorption of ClO4(-) ions. In the solutions with multiple anions present, the ClO4(-) SERS spectra were affected simultaneously by all the coexisting anions. Calibration curves with very good linear relationships were successfully obtained, demonstrating the great potential of quantitative detection of aqueous ClO4(-) in the matrix.
表面增强拉曼散射（SERS）已成为检测水中环境污染物（包括高氯酸盐（ClO4(-)））最灵敏的光谱分析方法之一。然而，与其他常用分析技术一样，由于实际环境样品中存在复杂的化学成分，利用SERS对其进行分析具有挑战性。在本工作中，我们使用阳离子硫醇修饰的银纳米薄膜基底（Cys-Ag/rCu）研究了无机阴离子（特别是含氧阴离子）对ClO4(-)的SERS光谱的影响。结果表明，样品中存在的阴离子并未使ClO4(-)特征谱带位置发生偏移，但由于它们与固定在基底上的阳离子硫醇分子的-NH3(+)基团发生竞争性结合，确实降低了信号强度。由H2PO4(-)解离和HCO3(-)水解引起的pH变化也可能起不可忽视的作用。确定Cys-Ag/rCu基底对这些阴离子的选择性顺序为：ClO4(-)>SO4(2-)>HCO3(-)，NO3(-)>Cl(-)>H2PO4(-)，表明ClO4(-)离子优先吸附。在存在多种阴离子的溶液中，ClO4(-)的SERS光谱同时受到所有共存阴离子的影响。成功获得了具有非常好线性关系的校准曲线，证明了对基质中水溶液ClO4(-)进行定量检测的巨大潜力。
