水体溶解态黑碳的分子标志物苯多羧酸的气相色谱-质谱分析

Analysis of benzene polycarboxylic acids as molecular markers of dissolved black carbon in water using gas chromatography-mass spectrometry

苯多羧酸分子标志物法是定量水体中溶解态黑碳的常用方法,然而由于部分苯多羧酸,尤其是硝基苯多羧酸商业化标准品的缺失,采用该方法定量溶解态黑碳仍需进一步完善和优化。本文通过已有的苯多羧酸商业化标准品,建立了气相色谱-质谱联用仪(GC-MS)分离和定量 9 种缺少商业化标准品苯多羧酸的分析方法。并首次将菲-D10 作为溶解态黑碳的替代物,指示苯多羧酸法定量溶解态黑碳过程中的损失率。结果表明,该方法具有良好的重现性(RSD=10.34%),方法检出限为 0.67~5.38 ng/L。本文采用该方法分析了大亚湾表层水体溶解态黑碳的分布特征,其浓度范围为 30.38~46.19 μg/L,平均值为(38.93±6.17)μg/L,空间分布表现为从湾内到外海递减的趋势。

The benzene polycarboxylic acids (BPCA) are commonly used as specific molecular markers to quantify dissolved black carbon (DBC) in water. Nevertheless, further optimization of the BPCA method is still needed because of the lack of set standards, especially those on nitro-benzene polycarboxylic acids. This study develops a gas chromatography (GC) method coupled with mass spectrometry (MS) for reliable separation and quantification of BPCAs without standards. Phenanthrene-D10 was first used as a substitute for DBC to correct the loss during the quantification of DBC by BPCA method. The method validation showed an excellent quantification reproducibility (RSD=10.34%). The method detection limits (MDLs) for specific compounds were in the range of 0.67-5.38 ng/L. The established method was proved to be efficient via measurement of DBC distribution in the surface water samples collected from the Daya Bay, the concentrations ranged from 30.38 to 46.19 μg/L with an average of (38.93±6.17)μg/L. the distribution also showed a decreasing trend from the inner bay to outer bay.