In splitless mode the split vent is closed during the first part of the injection. This means that the sample can only go down the column. This leads to much higher detection limits because most of the sample will go down the column instead of out the split vent. Splitless is used for low concentration samples. One thing to remember about splitless is that the gas flow through the liner is equal to the column flow. So the flow through the liner could be as low as 0.5ml/ min. This means you have to wait longer to flush the sample into the column before you start the temperature program. In fact the sample will take up to ten minutes to totally exit the liner. For this reason the split vent is always turned back on after 1 minute to quickly remove any residue left in the liner.
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