液相色谱-质谱法分析黑碳的分子标志物——苯多羧酸和硝基苯多羧酸

苯多羧酸法是定量检测黑碳和溶解态黑碳的重要分子标志物法,其中苯多羧酸和硝基苯多羧酸的分离和定量是关键环节。本文建立了苯多羧酸和硝基苯多羧酸的液相色谱-质谱分析方法,利用质谱的定性能力解决了部分苯多羧酸和硝基苯多羧酸化合物在缺乏标准品情况下的定性问题。用Phenomenex Synergi Polar RP分离柱,柱温为35 ℃,流动相为0.5%(体积分数)甲酸水溶液和甲醇,流速为0.5 mL/min,梯度洗脱,以电喷雾离子源负离子全扫描和选择扫描模式进行离子阱质谱检测,同时利用串联的二极管阵列检测器采集三维紫外光谱数据。在实际样品检测中,14个含3个及以上羧基的苯多羧酸和硝基苯多羧酸化合物获得良好分离。此方法简化并加快了苯多羧酸法定量黑碳和溶解态黑碳的分析过程,可满足环境样品中黑碳和溶解态黑碳的分析,促进了苯多羧酸法应用的普及。

Analysis of benzene polycarboxylic acids and nitro-benzene polycarboxylic acids as molecular tracers of black carbon by using liquid chromatography-mass spectrometry

The benzene polycarboxylic acid (BPCA) method is an important molecular marker method for black carbon and dissolved black carbon quantification while the separation and quantification of benzene polycarboxylic acids and nitro-benzene polycarboxylic acids are the key process. In order to use mass spectrometer to solve the issue of identification of benzene polycarboxylic acids and nitro-benzene polycarboxylic acids due to the lack of the standards of some of the target compounds, a liquid chromatography-mass spectrometry method was proposed. It made the experimental procedures easier and faster than using the gas chromatography mass spectrometry, and would promote the use of the BPCA method. A Phenomenex Synergi Polar RP column was used. The digestion productions of black carbon and dissolved black carbon were gradiently eluted by the mobile phases of 0.5%(v/v) aqueous formic acid solution and methanol with the flow rate of 0.5 mL/min at 35 ℃. The determination was conducted by an ion trap mass spectrometer in negative electrospray ionization (ESI) mode under full scan and selected ion monitoring (SIM) modes. Simultaneously the three-dimensional ultraviolet spectra were collected by a photo diode array detector. The LC-MS method was proved to be suitable for the analysis of environmental black carbon and dissolved black carbon.