UPLC-ESI-MS analysis of salts using a porous graphitic carbon column

Abstract

A method for the identification and quantification of salts relevant in the analysis of explosives was developed for a porous graphitic carbon (PGC) UPLC/HPLC column combined with ESI-MS detection. The presented method covers a wide range of energetic salts and provide a valuable analytical tool for security, forensic as well as environmental monitoring. Both anionic and cationic species can be identified and quantified in a single chromatographic run. Afterward, analytes can be indubitably identified by LC-MS equipped with an atmospheric pressure ionisation (API) interface. Since the retention mechanism of PGC is due to combination of different interactions, a tunable retention can be obtained by adjustments of the composition of the mobile phase. The use of LC-MS in combination with PGC is an improved alternative to the existing analytical methods based on silica derivatised reversed phase (RP) columns. A high percentage of ammonia in the mobile phase allowed elution of the most highly retained analytes. The effects of different solvents and their combinations and mobile phase additives were evaluated. The developed method improves the energetic salts detection in terms of sensitivity and selectivity. The effectiveness of the method is demonstrated by the analysis of a reference mixture of anions and cations.