. 2004 Jul;70(7):4048–4052. doi: 10.1128/AEM.70.7.4048-4052.2004

TABLE 2.

GC-MS analysis of CO₂ produced from ¹³C-labeled acetate

Dilution rate (day⁻¹)	Substrate	Peak intensities			CO₂ from methyl base/total CO₂	CO₂ from carboxyl base/total CO₂
		m/z 44 (¹²CO₂)		m/z 45(¹³CO₂) (actual)
		Actual	Background subtracted^a	m/z 45(¹³CO₂) (actual)
0.025	¹³CH₃¹²COONa	4,041^b	2,635	1,196	0.31	0.69
	¹²CH₃¹³COONa	3,424	2,018	4,296	0.32	0.68
	¹³CH₃¹³COONa	1,406		3,380
0.6	¹³CH₃¹²COONa	87,919	79,915	5,302	0.062	0.94
	¹²CH₃¹³COONa	12,951	4,947	80,702	0.058	0.94
	¹³CH₃¹³COONa	8,004		73,096

The peak intensities at an m/z value of 44 from ¹³CH₃¹³COONa were regarded as the background.

All values are averages for duplicate experiments.