基于纸喷雾离子化衍生质谱法快速检测PM2.5中的醌污染物

醌类化合物是P M2.5中的一类有害物质.本研究建立了纸喷雾离子化衍生质谱法快速测定P M2.5中的醌类污染物.通过衍生化反应在醌化合物中引入氨基,提高醌在纸喷雾中的离子化效率.随后对衍生化试剂种类、电压、喷雾溶剂种类等反应条件进行优化.在最优实验条件下,采用内标法定量分析1,4-苯醌、甲基对苯醌、1,4-萘醌和1,4...

Rapid Determination of Quinone Pollutants in PM2.5 by Derivative-based Paper Spray Ionization Mass Spectrometry

Quinones in PM2.5 are harmful substances that can damage body's immune system by generating reactive oxygen species (ROS), which are mainly produced by the incomplete combustion of fuels such as petroleum, coal, wood and cigarettes. Meanwhile, the gas-phase reaction between poly aromatic hydrocarbons (PAHs) and oxidative substances including ozone and radical species will result in the secondary formation of quinones. Rapid determination of quinones in PM2.5 is the basis for the health risk assessment and atmospheric environment quality control. However, the traditional methods for determining quinones in the atmosphere are time-consuming and labor-intensive, such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Here, paper spray mass spectrometry was introduced for the rapid determination of quinones in PM2.5, which was an ambient ionization technique developed in 2010. The ionization efficiency of quinones in paper spray is low for their weak polarity and low proton affinity. To improve their ionization efficiency, an amino group was introduced into the quinone structures through the derivatization reaction between thiol reagents and quinones. The reaction conditions, including the type of derivatization reagent (glutathione, cysteine and cysteamine), spray voltage (3-5 kV), and spray solvent composition (acetonitrile, acetonitrile-alcohol (1∶1, V/V), acetonitrile-methanol (1∶1, V/V), acetonitrile-ethyl acetate (1∶1, V/V), were optimized. The results showed that the best performances were achieved with cysteamine as the thiol reagent, 5 kV as the spray voltage, and acetonitrile as the spray solvent. Under the optimal conditions, the analysis performances of the derivative-based paper spray for the determination of four quinones (1,4-benzoquinone, methyl-p-benzoquinone, 1,4-naphthoquinone and 1,4-anthraquinone) were characterized. With BQ-D₄ and 1,4-NQ-D₆ as internal standards (IS), it showed good linearity for 1,4-benzoquinone (IS, BQ-D₄), methyl-p-benzoquinone (IS, BQ-D₄), 1,4-naphthoquinone (IS, 1,4-NQ-D₆) and 1,4-anthraquinone (IS, 1,4-NQ-D₆) analysis with correlation coefficients (R²) of 0.990, 0.993, 0.992, 0.990, respectively. Based on three times of the standard deviation of 11 blank values (3×δ_blank/k, k is the slope of the linear equation), the limits of detection (LODs) of BQ, MBQ, NQ and AQ were 4.49, 20.89, 0.13 and 0.17 ng, respectively. In addition, good qualitative and quantitative results were obtained for the analysis of 1,4-naphthoquinone and 1,4-anthraquinone in PM2.5. This work provides a rapid, simple, low-cost and environment-friendly method for the quality control of quinones in PM2.5. However, the repeatability and quantitative ability of the derivative-based paper spray mass spectrometry should be further improved in the future, such as by the means of modifying the chromatographic paper with nanomaterials.