A process for protecting a filament in a thermal conductivity detector from chemical corrosion includes changing the flow direction of the column effluent in the thermal conductivity detector to allow the column effluent to bypass the filament when an undesired compound appears in the column effluent. The flow direction of the column effluent in the thermal conductivity detector is changed when the undesired compound disappears from the column effluent to allow the column effluent to pass through the filament. A thermal conductivity detector that allows the column effluent to (1) bypass the filament when an undesired compound appears in the column effluent and (2) pass through the filament when the undesired compound disappears in the column effluent is also described.