TABLE 2.

Gas chromatographic detection of PFC tracers in rock fragment from core surfaces and interiors^a

Sample	Sample wt (g)	Total PFC wt (g) (10−10)b
Cotton swab		7.84
Core surface	5.23	2.73
Core interior	5.81	ND
Core interior	6.13	ND
Laboratory air		ND

^aThe cotton swab that wiped the inside of the core liner and the laboratory atmosphere were used as positive and negative controls for PFC determination, respectively.

^bND, not detected.