Figure 4.

Isotope difference (relative to the control values) of δ¹³C-CH₄ values of headspace air after the treatment of blood samples with ¹³C-labeled DMSO (a) and methionine (b) incubated over two days at a temperature of 36 °C. Mean values of three replicated experiments (n = 3) are shown and error bars mark the SD. Control samples (blood without the addition of isotopically labeled compounds) did not show any measurable difference in δ¹³C-CH₄ values over the incubation time, and thus, are not graphically illustrated.