Unified Gas Chromatographic Method for Determination of Methanol in Natural Gas and Related Products

Abstract

Method for determination of methanol traces in natural gas and the corresponding semi-products is developed. Method is based on pre-concentration of methanol from natural gas samples by passing it through two glasses containing water solution of sodium sulphate. Then the content of methanol was determined in the solutions obtained by analysis of their equilibrium gas phase at 60 ºC. For this purpose, gas chromatography with a packed column filled with a modified polymer adsorbent was applied. When probe containers with a volume of 300 ml are applied, the method developed allows to determine methanol in natural gas in the range 0.010-5 mg l1 (1.3x10-6 – 6.5x10-4 vol%). This high sensitivity of the method is reached due to the pre-concentration of the analyte. Partial separation of methanol from the matrix components allows to decrease partial superposition of chromatographic peaks of methanol and iso-butane that improves correctness of the analysis and decreases the detection limit. With the corresponding changes in the sample preparation procedures, the method developed may be used for analysis of various technological semi-products (such as non-stable and stable condensate), as well as wastes

Keywords

• natural gas, sewage, methanol, gas chromatography, head-space analysis