Proton-Transfer Reaction Mass Spectrometry

A study was conducted to demonstrate the development of proton-transfer reaction mass spectrometry (PTR-MS). It was demonstrated PTR-MS was a technique that was developed specifically for detecting gaseous organic compounds in air. PTR-MS technique originated from the development of the flowing afterglow method for investigating ion-molecule reaction kinetics. PTR-MS was developed by employing the mass filter in the selected ion flow tube (SIFT) to select specific ions before reaction with an analyte was performed and replaced with a hollow-cathode discharge source. The hollow-cathode discharge source generated H ₃O ⁺ with high efficiency without the need for a mass filter. It was demonstrated that significantly higher ion-molecule collision energies generated in PTR-MS when a drift tube was employed reduced the formation of H ₃O ⁺ and other cluster ions to negligible levels without sample dilution.