TABLE 1.

GC-MS analysis of CH₄ produced from ¹³C-labeled acetate

Dilution rate (day−1)	Substrate	Peak intensities			CH4 from carboxyl base/total CH4	CH4 from methyl base/total CH4
		m/z 15 (12CH4)		m/z 17(13CH4) (actual)
		Actual	Background subtracteda
0.025	13CH312COONa	2,695b	2,695	5,474	0.33	0.67
	12CH313COONa	1,139	1,139	928	0.45	0.55
	13CH313COONa	0		1,361
0.6	13CH312COONa	81,973	14,066	614,114	0.022	0.98
	12CH313COONa	636,401	562,089	13,860	0.024	0.98
	13CH313COONa	74,312		588,433

^aThe peak intensities at an m/z value of 15 from ¹³CH₃¹³COONa were regarded as the background.

^bAll values are averages for duplicate experiments.