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Setting Dead Times for Optimum Linear Velocity

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To set a dead time, inject 2.0 µL of a non-retained gaseous substance (compatible with the detector) via a standard 10 µL syringe with a PTFE-tipped plunger (cat.# 24557 or 24725) or draw 2 µL from the headspace over neat compounds. Accurately mark the injection starting time and peak elution time with an electronic integrator.

Detector Recommended Dead Volume Compounds
FID methane, propane, butane
TCD air*, methane, butane
NPD acetonitrile headspace vapors, air*
ECD air*, methylene chloride headspace vapors
ELCD dichlorodifluoromethane or methylene chloride headspace vapors
MS air*, propane, butane, argon
PID acetylene ethylene

* should be used only at lower oven temperatures

Some compounds may be slightly retained on thick-film phases (1.0 to 7.0µm) giving slightly erroneous dead volume times, however, they will be reproducible for similar column types.