

In
this typical methane/non-methane analysis, the non-methane
hydrocarbons were backflushed after the ethane peak, but
the valve timing could have been set to backflush after
the methane, or after the C3, C4, C5 or C6 hydrocarbons,
depending on the operator's needs.
The
sample is connected to the valve inlet port on the GC valve
oven, where it fills the 1mL sample loop on the gas sampling
valve. The valve is then automatically rotated to inject
the sample onto the column, which separates the methane
(and optionally the ethane) away from the rest of the hydrocarbons.
After the elution of the compound(s) of interest, the gas
sampling valve is automatically returned to the starting
position, which backflushes the rest of the hydrocarbons
into the detector.
The
single channel PeakSimple data system controls the temperature
programmable column oven and the gas sampling valve, collects
the data, quantitates the non-methane hydrocarbons, and
produces a printed report. The Method 25 GC comes standard
with a HayeSep-D column, but may be equipped with other
column types as desired.