W. Delgadomorales et al., ARSENIC IN NATURAL-GAS - ANALYSIS AND CHARACTERIZATION OF PIPELINE SOLIDS BY H-1-NMR AND OTHER METHODS, International journal of environmental analytical chemistry, 57(4), 1994, pp. 313-328
Natural gas from the Abo gas field in New Mexico is known to contain a
rsenic in the form of tertiary alkylarsines. Deposition of alkylarsine
sulfides near the pressure regulation equipment in the transmission l
ines may cause serious operational problems. H-1 NMR spectra of CDCl3
solutions of the pure compounds, trimethylarsine sulfide (TMAS), dimet
hylethylarsine 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 p
pm) and MDEAS (1.66 ppm). Based on this, a method for the analysis of
the pipeline solids has been developed. Analysis of two samples indica
te 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-1 NMR method has been confirme
d by GC-MS analysis of the pipeline solids. A study of the reaction, i
n the gas phase, between TMA and sulfur-containing compounds (H2S or C
H3SH) in the presence of potentially catalytic materials indicates tha
t the presence of H2O and a metal (Fe or Cr) is necessary for the form
ation of TMAS by the reaction of TMA with H2S.