scope:

This method is intended for the analysis of NGL mixtures which may contain nitrogen/air and carbon dioxide, as well as purity products that fall within the compositional ranges listed in Table 1.

The round-robin data includes a sample containing 62 mole percent of hexanes plus with a molecular weight of 93, therefore it is recommended that the analysis of samples containing a higher molecular weight hexanes plus be made in accordance with GPA 2103.

NOTE 1 - This method can be used for a hexanes plus analysis by adjusting the timing of the backflush event to occur following the elution of n-pentane.

CAUTION 1 - In the case of unknown samples with a relatively large hexanes plus fraction and where precise results are important, it is desirable to determine the molecular weight (or other pertinent physical properties) of this fraction. Since this method makes no provision for determining physical properties, the physical properties needed must be determined by extended analysis or agreed to by the contracting parties. The extended analysis will be performed according to GPA 2186.

The heptanes and heavier fraction if present in a sample is analyzed by either (1) use of a precut column to elute heptanes and heavier first as a single peak, or (2) reverse flow of carrier gas after n-hexane, and peak grouping of the heptanes plus fraction. No reverse of carrier is required for purity mixes without heptanes and heavier.