Table 1.

Metallic-impurities content (ppm) in synthetic and natural graphite, GO, and CRG materials as determined by ICP-MS analysis

	Fe	Co	Cu	Mo	Ni
Graphite synthetic	55.2 ± 1.3	0.03 ± 0.01	1.2 ± 0.2	0.45 ± 0.01	2.9 ± 0.6
GO (Staudenmaier)	39.0 ± 3.7	0.05 ± 0.01	3.0 ± 0.6	1.5 ± 0.2	3.17 ± 0.02
S-CRG	108.9 ± 16.7	0.07 ± 0.01	16.7 ± 0.3	< DL	20.2 ± 1.0
Graphite natural	4224 ± 250	3.30 ± 0.02	15.1 ± 0.7	18.1 ± 0.3	33.7 ± 2.8
GO (Hummers)	529.6 ± 32.4	0.09 ± 0.01	3.7 ± 0.8	1.5 ± 0.2	5.2 ± 0.6
N-CRG	927.6 ± 159.9	0.27 ± 0.01	16.6 ± 1.0	< DL	18.0 ± 1.7

DL, detection limit; ±, standard deviation.