Table 4.

Atomic constituents of brain material taken from National Institute of Standards and Technology (NIST) Listings, “Compositions of Materials used in STAR Databases” webpage.

Symbol	Fraction Mass	Symbol	Fraction Mass
H	0.110667	S	0.001770
C	0.125420	Cl	0.002360
N	0.013280	K	0.003100
O	0.737723	Ca	0.000090
Na	0.001840	Fe	0.000050
Mg	0.000150	Zn	0.000010
P	0.003540

source by: http://physics.nist.gov/cgi-bin/Star/compos.pl?matno=123.