Perfluorocarbon tracers (PFT) can be used to quantify the amount of core contamination due to drilling fluid. PFT is continuously pumped into the stream of drilling fluid to maintain a consistent concentration. Core subsamples are then measured in triplicate using µECD gas chromatography. Measured levels of PFT of the core outer surface, the outer core surface after undergoing a decontamination procedure, and the inner core are then compared to determine the degree of contamination.