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Inlets
PTV Inlet Practices and Rationales (cold split/splitless modes)
Parameter Selection/Setting Rationale
Injection mode Cold split
Cold splitless
Cold solvent vent
For general use and sample
screening
For trace analysis
LVI
Inlet temperature ramp rate Adjustable (i.e., 2°C/sec to
720°C/sec max)
Use slower ramp rates for labile,
complex, or large volume
samples
Use faster ramp rates for most
samples
Use faster ramp rates to shorten
splitless purge delay time
Ballistic Simpler, less expensive
instrumentation
Inlet liner Straight with silanized wool
Baffled
Packed with an adsorbent
For general use
For labile samples
For focusing gaseous injections
from auxiliary sampling devices
Injection volume 0.1 - 1.5 µL
5 - 50 µL for LVI
Use lower volumes for volatile
solvents and fast ramp rates
Use volumes larger than 1.5 µL
only in solvent-elimination mode
Sample Injection technique Autosampler or manual, fast or
slow
Not critical for cold split and
splitless modes
Oven temperature 10 - 25°C below solvent BP
Sample dependent
For proper solvent effect in
splitless mode
For split mode
Column flow 30 - 50 cm/sec Clears inlet faster
Less backflash
Septum purge 1 - 5 mL/min Minimizes ghosting
Quantification Any method Inherently reproducible
Low discrimination in cold
injection modes
Retention gap 1 - 3 m, deactivated Compensates for extended
flooded zone and solvent-column
incompatibility
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