Analysis of Arsine and Phosphine in Ethylene and Propylene with dedicated GC/MS Analyzer and High Efficiency Source

Developments in the area of metallocene catalysts have significantly increased productivity for the polymerization of ethylene and propylene. However, these catalysts can also be more susceptible to impurities such as arsine (AsH3 ), phosphine (PH3 ), hydrogen sulfide (H2S), and carbonyl sulfide (COS). This sensitivity to contaminants has driven a need to monitor impurities at the lowest possible detection levels. Contaminants can degrade a polymerization catalyst sooner than desired, and can potentially shut down the production process for catalyst replacement. Precise, low-level detection of these contaminants during the production process offers the ability for olefin producers to take steps to mitigate these contaminants. The challenge for analysis is resolving significant matrix peaks from low-level, active contaminants, which necessitates an inert pathway. Low-level parts per billion (ppb) detection limits also require excellent system sensitivity, which can be achieved using a high efficiency source (HES). Analysis using gas chromatography/mass spectrometry (GC/MS) must provide high resolution, high capacity, high sensitivity, and an inert sample fl ow path. To achieve the required chromatographic resolution and capacity, a thick fi lm column is required. The addition of 150 µL/min of H2 into the source during data acquisition provides continuous source cleaning, and eliminates dropping peak responses that arise from higher column bleed introduced by the thick film. In this work, we present the solution provided by Agilent with an Arsine Phosphine GC/MS dedicated analyzer with the HES and Self Cleaning Ion Source (SCIS) that can enable a quick start-up for the analysis of arsine and phosphine at low ppb concentrations with high precision, stability over time, and ease-of-use.