Selective screening for 'unknown' phosphorous-containing compounds using high-resolution accurate-mass LC-MS

An analytical technique was developed for the detection of phosphorus-containing compounds, using high-resolution-accurate-mass (HRAM) LC-MS. This method was constructed as a “flagging” approach for chromatographic peaks of compounds suspected of containing phosphorus, using high-energy in-source CID fragmentation, in parallel with a Full-MS experiment. Selective peak picking is achieved by tracking the highly resolved low m/z product ions of phosphorus-containing products, indicative of several phosphate and phosphonate groups. The chemical formula is then specifically assigned by a simultaneous accurate mass measurement of the precursor ion, together with the confirmed presence of a phosphorus atom in the suspect peak. This new method is demonstrated with various phosphorus-containing compounds such as V-class chemical warfare agents, nerve agents’ degradation products, pesticides, organic phosphates and a phospholipid. For these compounds, the developed method was found to be effective at concentrations as low as 1 ng/mL, in environmental extracts of soil and in urine (in the case of the phospholipid), making it comparable to selective phosphorus detectors such as GC-FPD, but with a much broader scope for charged, polar, or larger compounds.