Introduction
1-12
Septum – Silicone rubber material placed in the injection port through which the
injection is made. When the needle is withdrawn, the silicone rubber reseals,
thus not allowing any sample or carrier gas to escape.
Stationary phase – The liquid or solid adsorbent portion of the column that
retains components passing through the GC column.
Subambient – Below ambient temperature. The oven cools down below
ambient temperature with the use of either liquid nitrogen or liquid carbon
dioxide.
Syringes – Precision dispensing devices used to deliver sample to the GC.
Liquid and gas syringes are available.
Tailing – When a peak is not symmetrical or Gaussian shaped but the back end is
broadened, it is said to be tailing.
Temperature programming – A technique commonly used to increase the rate of
elution of the components. After the sample is injected into the oven at a specific
temperature, the temperature program increases the oven temperature to the
prescribed temperature at a defined rate (in
°C/min).
Unretained peak – A component that is not retained by the column. The time
taken for an unretained sample to pass through the column is the same time as the
time taken for the carrier gas to pass through.
Velocity programming – Programmed linear velocity where the PPC controller
interprets stored PPC programs as the average capillary column linear velocity
settings.
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