Analysis of gaseous arsenic species and stability studies of arsine and trimethylarsine by gas chromatography-mass spectrometry

A rapid method based on gas chromatography-mass spectrometry was developed for analysis of four volatile arsenic species: arsine, monomethylarsine (MMA), dimethylarsine (DMA) and trimethylarsine (TMA). With the proposed method gaseous arsenic species could be determined in less than 2 min and no pre-treatment for gas phase samples was needed, which minimized the risks of species conversion before analysis. The detection limits for different species were 24–174 pg. The standards for arsine, MMA and DMA were prepared by reaction between arsenic acid, monomethylarsonic acid or dimethylarsinic acid with tetrahydroborate(III) and nitric acid. The effect of pH on recovery of different arsine species was examined and is discussed. The TMA was obtained commercially as liquid. Also stability of inorganic (arsine) and organic (TMA) gaseous arsenic species in air was studied as a function of time.