Element

Before washing

After washing

Mass (%)

Standard deviation (%)

Mass (%)

Standard deviation (%)

C

27.01

±1.22

32.23

±1.18

N

16.87

±2.04

0

-

O

33.33

±0.69

35.04

±0.63

Mg

4.15

±0.10

2.19

±0.09

Al

1.22

±0.22

2.13

±0.05

Si

7.48

±0.19

11.54

±0.11

P

3.34

±0.01

0

-

Ti

0.78

±0.16

3.7

±0.11

Cr

-

-

1.17

±0.11

Fe

5.82

±0.33

12.00

±0.41

Total

100

100