采用荧光分光光度计测定蒽、萘和8-羟基喹啉在不同低共熔溶剂(DESs)中的荧光强度,探究DESs对分子荧光性能的影响,并将其应用于土壤中蒽的定量分析。结果表明:极性较弱的甲基三辛基氯化铵-正癸酸、甲基三辛基氯化铵-十二醇等脂溶性DESs不仅可使蒽的荧光强度显著增强,还可以改善其发射峰峰形;萘和8-羟基喹啉在DESs中会发生荧光猝灭,同时产生发射峰位移。土壤样品经二氯甲烷提取、硅胶固相萃取柱净化后,所得残渣用1%(体积分数)甲基三辛基氯化铵-正癸酸溶液溶解。设置激发波长为350 nm,采用荧光分光光度计测量待测样品溶液在362 nm处的荧光强度。结果显示:蒽的质量浓度在0.1~10.0 μg·L^-1内与对应的荧光强度呈线性关系,检出限(3s/k)为0.3 ng·g^-1,低于以二氯甲烷作溶剂时的检出限(1.5 ng·g^-1);采用标准加入法对空白样品进行3个浓度水平的加标回收试验,回收率为89.5%~96.5%,测定值的相对标准偏差(n=6)均小于4.0%;与常规溶剂二氯甲烷相比,该方法灵敏度高、检出限低,有效改善了蒽的发射峰峰形,便于对土壤中蒽的准确定量分析。

The fluorescence intensities of anthracene, naphthalene and 8-hydroxyquinoline in different deep-eutectic solvents (DESs) was determined by fluorescence spectrophotometer, and the effect of DESs on molecular fluorescence properties was investigated, and it was used for the quantitative analysis of anthracene in soil. It was shown that fat-soluble DESs with weak polarity, such as methyl trioctylammonium chloride-n-capric acid and methyl trioctylammonium chloride-dodecyl alcohol, could not only significantly enhance the fluorescence intensity of anthracene, but also improve its emission peak shape. The fluorescence quenching of naphthalene and 8-hydroxyquinoline occurred in DESs, resulting its emission peaks displacement. The soil sample was extracted by dichloromethane and purified by silica gel solid phase extraction column, and the residue was dissolved by 1% (volume fraction) methyl trioctylammonium chloride-n-capric acid solution. The fluorescence intensity of the testing sample solution at 362 nm was determined by fluorescence spectrophotometer with excitation wavelength of 350 nm. As shown by the results, linear relationship between the mass concentration of anthracene and the corresponding fluorescence intensity was kept in the range of 0.1-10.0 μg·L^-1, with detection limit (3s/k) of 0.3 ng·g^-1, which lower than that of dichloromethane as solvent (1.5 ng·g^-1). Test for recovery was made on the blank sample by standard addition method at 3 concentration levels, giving results in the range of 89.5%-96.5%, and RSDs (n=6) of the determined values were less 4.0%. Compared with conventional solvent dichloromethane, this method had high sensitivity and low detection limit, effectively improved emission peak shape of anthracene, and facilitated accurate quantitative analysis of anthracene in soil.