HP 5890 Series II Plus Reference Manual page 119

Inlet Systems
Split/splitless capillary inlet
Figure 6-10
Area
Counts
Effect of Inlet Purge Activation Time on Area Counts
Noting Figure 6•10,waiting too long does not increase component peak
areas, but does increase interference by the solvent tail. Purging too early
risks venting light components, not allowing sufficient time for heavier
components to enter the column, and/or not having sufficient solvent
enter the column to ensure good reconcentration.
A recommended procedure is to analyze a known standard using
conditions identical to those to be used for later sample analyses. Ideally,
the standard should be representative (in both components chosen and
their respective concentrations) of unknown samples to be analyzed.
Perform a series of analyses with increasingly delayed insert purge times:
the optimal time is where maximum area counts are obtained with least
interference by the solvent.
10 20 30
Purge Activation Time, Sec
+ 1.2% Deviation
20 ppm n-C (Cold Trapped)
~ 14
+ 1.2% Deviation
10 ppm n-C (Solvent Effect)
~ 11
Solvent: Isooctane
Column: 16.5 m x 0.25 mm SE-54 –
80 C (0.5 min) 170 C @ 15 /min
Sample Size: 1.3 ml (Manual Injection)
Injection Rate: 1 ml/sec
Purge Flows: 5 ml/min, Septum: 60 ml/min, Inle
40 50 60
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