HP 5890 Series II Plus Reference Manual page 118

Inlet Systems
Split/splitless capillary inlet
A recommended procedure is to perform a series of analyses at
increasingly higher inlet temperatures using components representative
of those of interest, and analyzed using the conditions for later sample
analyses. The optimum temperature is where maximum area counts are
obtained, and there is no evidence of thermal degradation products.
Solvent purity
Reconcentration traps any solvent impurities at the head of the column,
which may interfere with peaks of interest. A solvent blank run to check
solvent purity is strongly recommended before the solvent is used to
dilute samples for analysis.
Inlet insert purge
After injection, sufficient time is allowed for solvent and sample
components to reconcentrate at the head of the column; then solvent
vapor within the inlet insert is vented (purged).
The specific time delay after injection for insert purging to occur depends
upon the components, solvent, and injection volume, flow rate through
the inlet, and internal insert volume (approximately 1 ml); generally, a
time within the range 0.3 to 2 minutes is reasonable.
118