Triazine-Based Covalent Organic Framework: A Promising Sorbent for Efficient Elimination of the Hydrocarbon Backgrounds of Organic Sample for GC–MS and 1H NMR Analysis of Chemical Weapons Convention Related Compounds

The strict monitoring and precise measurements of chemical warfare agents (CWAs) in environmental and other complex samples with high accuracy have great practical significance from the forensic and Chemical Weapons Convention (CWC) verification point of view. Therefore, this study was aimed to develop an efficient extraction and enrichment method for identification and quantification of toxic agents, especially with high sensitivity and multidetection ability in complex samples. It is the first study on solid-phase extraction (SPE) of CWAs and their related compounds from hydrocarbon backgrounds using covalent triazine-based frameworks (CTFs). This nitrogen-rich CTF sorbent has shown an excellent SPE performance toward sample cleanup by selective elimination of hydrocarbon backgrounds and enrich the CWC related analytes in comparison with the conventional and other reported methods. The best enrichment of the analytes was found with the washing solvent (1 mL of n-hexane) and the extraction solvent (1 mL of dichloromethane). Under the optimized conditions, the SPE method had good linearity in the concentration range of 0.050-10.0 μg mL^-1 for organophosphorus esters, 0.040-20.0 μg mL^-1 for nerve agents, and 0.200-20.0 μg mL^-1 for mustards with correlation coefficients ( r²) between 0.9867 and 0.9998 for all analytes. Limits of detection ( S/ N = 3:1) in the SIM mode were found to be in the range of 0.015-0.050 μg mL^-1 for organophosphorus esters, 0.010-0.030 μg mL^-1 for nerve agents, and 0.050-0.100 μg mL^-1 for blister agents. Limits of quantification ( S/ N = 10:1) were found in the range of 0.050-0.200 μg mL^-1 for organophosphorus esters, 0.040-0.100 μg mL^-1 for nerve agents, and 0.180-0.350 μg mL^-1 for blister agents in the SIM mode. The recoveries of all analytes ranged from 87 to 100% with the relative standard deviations ranging from 1 to 8%. This method was also successfully applied for the sample preparation of ¹H NMR analysis of sulfur and nitrogen mustards in the presence of hydrocarbon backgrounds. Therefore, this SPE method provides the single sample preparation for both NMR and GC-MS analyses.