大气细粒子中阴离子表面有机活性物质分析方法的优化

为优化大气细粒子中阴离子表面有机活性物质的亚甲蓝分光光度法和乙基紫分光光度分析法,分别从样品前处理和分析测定两方面对分析方法进行优化,并采用2种优化方案对北京市大气细粒子样品进行分析测定. 结果表明:①2种优化方案的最佳超声提取频率、最佳初始水浴温度和最佳超声提取时间均分别为40 Hz、30 ℃和35 min；②亚甲蓝优化方案的最佳显色剂使用量为0.70 mg,其中中性亚甲蓝和酸性亚甲蓝使用量均为0.35 mg,最佳静置时间为30~45 min；③乙基紫优化方案的最佳显色剂使用量为0.098 mg,最佳静置时间为30 min,最佳辅助性试剂使用量分别为pH＝5的醋酸盐缓冲液0.4 mL,乙二胺四乙酸二钠10 μmol,硫酸钠0.25 mmol. 采用2个优化方案测得的北京市大气细粒子样品中ρ(MBAS)(MBAS为亚甲蓝活性物质)和ρ(EVAS)(EVAS为乙基紫活性物质)分别为0.14～0.39和0.14～0.47 μg/m3. 与亚甲蓝优化方案相比,乙基紫优化方案的试验操作更简便、标准曲线线性关系更好,更适合大气细粒子中阴离子表面有机活性物质的测定. 

Optimization of Analytical Methods for Determining Anionic Surface Organic Active Substances in Atmospheric Fine Particles

In order to optimize methods for determining the concentrations of anionic surface organic active substances in atmospheric fine particles, the Methylene Blue Spectrophotometric and Ethyl Violet Spectrophotometric Methods for the characterization of surface organic active substances in fine particles were optimized from two aspects-pretreatment and analytical parameters. In addition, the two optimized methods were applied to measure the mass concentrations of surface organic active substances in fine particle samples collected in Beijing. The results showed that:1) The optimal frequency, initial bath temperature and extraction time for ultrasonic extraction with the two methods were consistent:40 Hz, 30 ℃ and 35 min. 2) For the Methylene Blue Spectrophotometric Method, the optimal amount of chromogenic reagent was 0.35 mg of neutral methylene blue and 0.35 mg of acidic methylene blue, and the optimal standing time was controlled in the range of 30-45 min. 3) For the Ethyl Violet Spectrophotometric Method, the optimal amount of chromogenic reagent was 0.098 mg, the optimal standing time was 30 min, and the optimal amount of the auxiliary reagents were 0.4 mL of acetate buffer (pH=5), 10 μmol of EDTA and 0.25 mmoL of sodium sulfate. The determined values for the mass concentrations of the surface organic active substances in the fine particles were 0.14-0.39 μg/m3 and 0.14-0.47 μg/m3, respectively, acquired using the optimal experimental schemes for the Methylene Blue Spectrophotometric Method and the Ethyl Violet Spectrophotometric Method. Compared with the Methylene Blue Spectrophotometric Method, the Ethyl Violet Spectrophotometric Method has more convenient operation steps and a better linear standard curve. In conclusion, the Ethyl Violet Spectrophotometric Method is more applicable for the measurement of surface organic active substances in atmospheric fine particles.