In a miniaturized gas chromatography system, there could be identification doubt between compounds eluting at close retention times. When a sensor is a thermal conductivity detector (TCD), we investigated a double-measurement approach (two temperatures) to improve specificity. Unfortunately, both theory and experiments showed that this method could only work for relatively high compound concentrations (1–50 ppm). This is therefore not relevant for a trace analysis system (1–10 ppb).