Table 3.

SRM 1649a Isotopic (¹⁴C) Speciation

	fM (modern-C)	u(fM)a	fC (biomass-C)
Total Carbon (Team)
Combustion-Manometry (16)	0.61	0.04	0.45
H3PO4-Combustion-Manometry (13)	0.505	0.003	0.374
Combustion-GC-CHN (17)	0.517	0.004	0.383
Elemental Carbon (Team)
Thermal oxidation/residue (4)	0.065	0.003 (n = 3)	0.048
Chemical oxidation/residue (13)	0.153	0.002	0.113
Thermal kinetic oxidation/intercept (5)	0.038	0.012	0.028
Organic Fractions (Team)
Polar Carbon (4, 15)	0.43	0.01	0.32
Aromatic Carbon (16)	0.17	0.04	0.13
Aliphatic Carbon (4, 15)	0.024	0.006	0.018
Individual PAH (Teams = 4, 15)
Phenanthrene	0.0406	0.0049	0.0301
Methylphenanthracenes	0.0434	0.0057	0.0321
Fluoranthene	0.0637	0.0026	0.0472
Pyrene	0.0372	0.0022	0.0276
Benz[a]anthracene	0.0413	0.0037	0.0306
Chrysene/Triphenylene	0.0553	0.0030	0.0410
Benzofluoranthenes (b,j,k)	0.0842	0.0027	0.0624
Benzo[ghi]perylene	0.0864	0.0046	0.0640

^aPoisson standard uncertainties (u) are given for all f_M values except the first EC datum, where u is based on replication (n = 3).