建立了一种用维多利亚蓝B(VBB)简便、 高灵敏、 选择性检测全氟辛烷磺酸(PFOS)的共振光散射(RLS)分析方法。 在pH 6.0的KH2PO4-NaOH缓冲体系下, PFOS通过静电作用与质子化的VBB结合生成离子缔合物, 在277 nm处的散射信号有明显的增强, 增强的散射值(ΔIRLS)与PFOS在一定浓度范围内有良好的线性关系, 其线性方程为ΔIRLS=72.28+336.53c (r=0.996 4), 线性范围为0.05~4.0 μmol·L-1, 检测限为5.0 nmol·L-1。 优化了实验条件, 表征了紫外/可见吸收光谱、 扫描电镜显微成像(SEM), 并探讨了作用机理。 在相同实验条件下, 考察了全氟辛酸(PFOA)及其他几种全氟化合物(PFCs)与VBB的相互作用, 未见散射信号变化, 因此, 本法可实现对PFOS的选择性检测。 该方法成功应用于检测环境水样中的PFOS, 样品加标回收率为91.8%~100.6%, 相对标准偏差RSD≤1.74%。

This report presents a simple, sensitive and selective victoria blue B (VBB)-based resonance light scattering (RLS) assay of perfluorooctane sulfonate (PFOS). In pH 6.0 KH2PO4-NaOH buffer solution, VBB can be protonated and reacts with PFOS through electrostatic interactions to produce ionic-association complexes. Simultaneously, the interaction leads to enhanced resonance light scattering intensities greatly, which are characterized with a peak at 277 nm. It is found that the enhanced RLS intensity is proportional to the concentration of PFOS in a range of 0.05 to 4.0 μmol·L-1. The limit of detection is 5.0 nmol·L-1. While, under the optimal experimental conditions, almost no change of the resonance light scattering intensity was observed between VBB and perfluorooctane acid (PFOA) which is one kind of representative perfluorinated compounds (PFCs). The excellent selectivity of PFOS could be due to the hydrophobicity of PFOS higher than PFOA. It is worth noting that the proposed method is capable of differentiating PFOS and some other PFCs. UV/Vis absorption spectrum and scanning electron microscope (SEM) image both were investigated to further validate the reaction mechanism. The interference of coexisting foreign substances and the optimum tests of reaction conditions, including pH value, reaction time, experimental temperature and ionic strength, were also investigated. This method has been successfully applied to the determination of PFOS in environmental water samples with RSD ≤1.74%. The experimental process as followed: In 2 mL colorimetric tube, 200 μL pH 6.0 KH2PO4-NaOH buffer solution, followed by adding 600 μL 20 μmol·L-1 VBB solution, swirl evenly, then add the right amount of PFOS solution. After vortex mixing with ultrapure water volume to 2 mL, swirl to mix, stand for 10 min at room temperature. Then the mixture was transferred for RLS measurements and absorption measurement.