Table 1.

Relative peak areas of individual mass traces for selectively ¹³C-labeled 6PG, F6P, and FBP

	M0	M1		M2
	m0	m0	m1	m0	m1	m2
Labeled species	Relative signal intensity
6PG	m/z = 129 (assumed origin: [1–5])
12C	0.90 (0.91)	0.02 (0.01)	0.05 (0.05)	0.01 (0.01)	0.00 (0.00)	0.01 (0.01)
1-13C	0.00 (0.01)	0.01 (0.00)	0.93 (0.91)	0.00 (0.00)	0.01 (0.01)	0.05 (0.04)
2-13C	0.01 (0.01)	0.01 (0.00)	0.93 (0.91)	0.00 (0.00)	0.01 (0.01)	0.04 (0.04)
1,2-13C	0.00 (0.00)	0.00 (0.00)	0.02 (0.02)	0.00 (0.00)	0.01 (0.00)	0.97 (0.92)
6-13C	0.06 (0.01)	0.88 (0.91)	0.00 (0.00)	0.00 (0.00)	0.05 (0.05)	0.00 (0.00)
F6P	m/z = 101 (assumed origin: [3–6])
12C	0.93 (0.92)	0.02 (0.02)	0.04 (0.04)	0.01 (0.01)	0.00 (0.00)	0.00 (0.01)
1-13C	0.04 (0.01)	0.67 (0.92)	0.24 (0.00)	0.01 (0.01)	0.04 (0.04)	0.01 (0.00)
2-13C	0.05 (0.01)	0.62 (0.92)	0.28 (0.00)	0.01 (0.01)	0.03 (0.04)	0.01 (0.00)
1,2-13C	0.01 (0.00)	0.04 (0.02)	0.01 (0.00)	0.65 (0.92)	0.05 (0.00)	0.24 (0.00)
6-13C	0.03 (0.01)	0.29 (0.00)	0.62 (0.92)	0.00 (0.00)	0.03 (0.02)	0.02 (0.03)
F6P	m/z = 169 (assumed origin: [4–6])
12C	0.92 (0.92)	0.03 (0.03)	0.03 (0.03)	0.01 (0.01)	0.00 (0.00)	0.01 (0.01)
1-13C	0.05 (0.01)	0.89 (0.92)	0.00 (0.00)	0.02 (0.02)	0.03 (0.03)	0.00 (0.00)
2-13C	0.07 (0.01)	0.87 (0.92)	0.00 (0.00)	0.02 (0.02)	0.03 (0.03)	0.00 (0.00)
1,2-13C	0.01 (0.00)	0.07 (0.02)	0.00 (0.00)	0.92 (0.92)	0.00 (0.00)	0.00 (0.00)
6-13C	0.01 (0.01)	0.01 (0.00)	0.92 (0.92)	0.00 (0.00)	0.03 (0.03)	0.02 (0.02)
FBP	m/z = 139 (assumed origin: [5, 6])
12C	0.91 (0.91)	0.05 (0.04)	0.02 (0.02)	0.01 (0.01)	0.00 (0.00)	0.01 (0.01)
1-13C	0.06 (0.01)	0.87 (0.91)	0.01 (0.00)	0.03 (0.03)	0.02 (0.02)	0.00 (0.00)
2-13C	0.07 (0.01)	0.86 (0.91)	0.01 (0.00)	0.03 (0.03)	0.02 (0.02)	0.00 (0.00)
6-13C	0.01 (0.01)	0.03 (0.00)	0.90 (0.91)	0.00 (0.00)	0.04 (0.04)	0.01 (0.01)
FBP	m/z = 169 (assumed origin: [4–6])
12C	0.91 (0.91)	0.04 (0.03)	0.04 (0.03)	0.01 (0.01)	0.00 (0.00)	0.00 (0.01)
1-13C	0.06 (0.01)	0.89 (0.91)	0.04 (0.00)	0.00 (0.02)	0.00 (0.03)	0.00 (0.00)
2-13C	0.07 (0.01)	0.89 (0.91)	0.04 (0.00)	0.00 (0.02)	0.00 (0.03)	0.00 (0.00)
6-13C	0.02 (0.01)	0.05 (0.00)	0.92 (0.91)	0.02 (0.00)	0.00 (0.03)	0.00 (0.02)

M0, M1, and M2 signify that the quadrupole 1 was set to the mass of the M0, M1, and M2 mass isotopomer of the metabolite in question. m1, m2, and m3 denote that the quadrupole 3 was set to the mass of the m0, m1 and m2 tandem mass isotopomer of the fragment in question. The arising precursor-daughter mass transitions can be found in Electronic Supplementary Material S3. Bold face: measured experimental relative mass trace intensity, italic face: theoretical fractional abundance arising from the assumed carbon origin of the fragment indicated after the fragment mass. The theoretical abundance was calculated according to the method provided in Electronic Supplementary Material S8