A0.7 ml mixture of pentanol and heptanol are separated and collected using preparative gas chromatography on a gc fitted with a polar column and a tcd detector. during the separation, why are the injection port and detector heated to a higher temperature than the column? a heated injector creates flash vaporization which allows separation at temperatures lower than the boiling point of the sample. all samples leaving the column must be vaporized before leaving the gc, so the thermal conductivity detector is run at a hot temperature. the injector must be kept at a higher temperature than the column to allow the sample the opportunity to effectively solidify in the column. the wire in the thermal conductivity detector needs to be cooled by the eluent in order to register a signal.