A mass spectrometric study of hydride generated arsenic species identified by direct analysis in real time (DART) following cryotrapping

Hydride generation (HG) coupled to cryotrapping was employed to introduce, separately and with high selectivity, four gaseous arsanes into a direct analysis in real time source for high-resolution mass spectrometry (DART-HR-MS). The arsanes, i.e., arsane (AsH3), methylarsane (CH3AsH2), dimethylarsane ((CH3)(2)AsH), and trimethylarsane ((CH3)(3)As), were formed under HG conditions that were close to those typically used for analytical purposes. Arsenic containing ion species formed during ambient ionization in the DART were examined both in the positive and negative ion modes. It was clearly demonstrated that numerous arsenic ion species originated in the DART source that did not accurately reflect their origin. Pronounced oxidation, hydride abstraction, methyl group(s) loss, and formation of oligomer ions complicate the identification of the original species in both modes of detection, leading to potential misinterpretation. Suitability of the use of the DART source for identification of arsenic species in multiphase reaction systems comprising HG is discussed.

Automated summary

Hydride generation coupled with cryotrapping was used to introduce four gaseous organoarsenic compounds into a direct analysis in real-time source for high-resolution mass spectrometry (DART-HR-MS). The study showed that numerous arsenic ion species were formed in the DART source, but did not accurately reflect their origin due to oxidation, hydride abstraction, methyl group(s) loss, and formation of oligomer ions. This complicates the identification of original species in both detection modes, potentially leading to misinterpretation.