Triazine-Based Covalent Organic Framework: A Promising Sorbent for Efficient Elimination of the Hydrocarbon Backgrounds of Organic Sample for GC-MS and 1 H 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 multi-detection ability in complex samples. It is the first study on solid phase extraction (SPE) of CWAs and their related compounds from hydrocarbon background using covalent triazine-based frameworks (CTFs). This nitrogen rich CTFs sorbent has shown an excellent SPE performance towards sample clean-up 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 n-hexane and the extraction solvent 1 mL dichloromethane (DCM). Under the optimized conditions, the SPE method had good linearity in 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 0.9867-0.9998 for all analytes. Limits of detection (LOD) (S:N=3:1) in SIM mode was 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. Limit of quantification (LOQ) (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 SIM mode. The recoveries of all analytes ranged from 87-100 % with the relative standard deviations (RSDs) ranging 1- 8 %. This method was also successfully applied for the sample preparation of 1H-NMR analysis of sulfur and nitrogen mustards in presence of hydrocarbon backgrounds. Therefore, this SPE method provides single sample preparation for both NMR and GC-MS analysis.