Arsenic in natural gas : analysis and characterization of pipeline solids by 1H NMR and other methods

Abstract Natural gas from the Abo gas field in New Mexico is known to contain arsenic in the form of tertiary alkylarsines. Deposition of alkylarsine sulfides near the pressure regulation equipment in the transmission lines may cause serious operational problems. 'H NMR spectra of CDCl3 solutions of the pure compounds, trimethylarsine sulfide (TMAS), dimethylethylarsine sulfide (DMEAS) and methyldiethylarsine sulfide (MDEAS) were measured. The signlet resonance of the CH3- group bonded to As is well separated in the three compounds: TMAS (1.83 ppm), DMEAS (1.74 ppm) and MDEAS (1.66 ppm). Based on this, a method for the analysis of the pipeline solids has been developed. Analysis of two samples indicate that the pipeline solids have the following composition, DMEAS (42.8–46.0%), TMAS (35.4–36.3%), MDEAS (4.7–10.9%). The identification of the arsenic compounds obtained by the 'H NMR method has been confirmed by GC-MS analysis of the pipeline solids. A study of the reaction, in the gas phase, between TMA and...