Determination of organic and inorganic Cl in gaseous ethylene based on gas-liquid equal mass response followed by automatic quick furnace-ion chromatography

Abstract

Herein, a practical method for the determination of organic and inorganic Cl in gaseous ethylene by liquid standard samples was established; and then, the effects of various speciation and matrices on results were investigated followed by automatic quick furnace-ion chromatography (AQF-IC) analysis. From the evaluation of speciation and matrices, unified equation was explored and the method for accurately determining trace HCl with strong adsorption was also developed. First, summarize regularity that the light oil liquid standards themselves conformed to equal Cl mass response by AQF-IC (R2=0.99993). Then, the actual Cl mass in standard gas at 4 levels with different speciation and matrices were calculated by the same regularity based on the assumption of not affected by speciation or matrix change. The gas mass was accurately calculated based on Van der Waals’ Equation. As a result, combined with the theoretical Cl mass calculated by equation, the recoveries of the organic and inorganic Cl were in the range of 93.0%-101.4% [2.0 µmol/mol of CH3Cl/(N2+ethylene)], 93.4%-104.9% (10.1 µmol/mol of CH3Cl/N2), 101.6%-111.2% (20.2 µmol/mol of CH3Cl/ethylene) and 95.3%-101.0% (11.0 mg/m3 of HCl/N2), respectively, indicating the successful verification of above assumption rather than applying more exploration to rebuild relationships between different systems. As proof of principle and for more verification, system of CH2Cl2/He gas standard sample was prepared to explore the quantitative accuracy in more speciation with recoveries in the range of 91.3%-98.5%. In addition, the detection limit of Cl content based on S/N = 3 for ethylene was 0.06 mg/kg. Intra-day and inter-day relative standard devations (RSDs) were in the range of 9.3%-12.0% (≤1.0 mg/kg) and 2.5%-4.4% (>1.0 mg/kg). Finally, the developed method based on gas-liquid equal mass response was successfully applied in the actual samples of light olefins such as ethylene and propylene.