A Novel Strategy to Evaluate the Aromaticity Degree of Natural Organic Matter Based on Oxidization-Induced Chemiluminescence

摘要

Due to its complex composition and structure, many of the properties of natural organic matter (NOM) are poorly understood. In this study, the oxidization-induced chemiluminescence (OCL) of NOM was investigated, and a flow-injection OCL method was developed using alkaline persulfate-H_2O_2 as the oxidizing agent The method is suitable for the direct analysis of NOM in both homogeneous and heterogeneous samples without isolation or concentration. A strong linear relationship (p ＜ 0.001) was found between the normalized organic carbon OCL (OCL_(OC)) and the percentage of aromatic carbon in standard NOM and soil samples, suggesting that OCL_(OC) can be used as an empirical indicator to assess the aromaticity degree of NOM in both homogeneous and heterogeneous samples. By using this method, the percentages of aromatic carbon in a forest soil profile with low organic carbon content were estimated, and a decrease in the degree of aromaticity in deeper soil was observed. Considering the high sensitivity (lower than 0.1 mg CL_(-1)) and throughput (13 s per detection) and low sample consumption (less than 1 mg) of the method, the proposed OCL_(OC) indicator shows great promise for the high-throughput evaluation of the aromaticity degree of NOM for a wide variety of environmental and geochemical samples.