Rapid Componental Analysis of Natural Gas by GC with Three Detection Channels

Gas chromatograph equipped with 5 valves (2 10-way valves and 3 6-way valves), 7 columns (2 capillary columns and 5 packed columns) and 3 detectors (FID A, TCD B and TCD C), was used for componental analysis of natural gas. By applying the switching system of the valves and the pre-set analytical program, determination of the common components of a natural gas sample could be realized by a single sample introduction. Qualitative detections were performed on the base of retention times of the components in standard samples, and quantitative analysis was performed by the external standard method. Precision of the method was tested, giving results of repeatability and reproducibility in conformity with the requirements stated in the standard GB/T 13610-2003. The relative errors between the values of components in a mixed standard of standard gases found by this method and the standard values were all found to be less than 5%.