A gas chromatographic method for the quantative determination of natural gas constituents using a two-column system is described in this part of ISO 6974. It is applicable to determinations made in the laboratory or in on-line processes. It also applies to the analysis of gases containing constituents within the mole fraction ranges given in Table 1. These ranges do not represent the limits of detection, but the limits within which the stated accuracy of the method applies. Although one or more components in a sample may not be detected present, the method can still be applicable. Only applicable if used in conjunction with Parts 1 and 2 of ISO 6974. TABLE 1 - APPLICATION RANGES forms part of this scope.