Element

Certified Concentration (MAD)

Observed Concentration (n = 3)

Rel. Error (%)

Recovery (%)

Cu

6.05 (3.50)

(n = 6)

7.73 ± 0.98

27.8

+127.8

Cr

2.35 (1.65)

(n = 4)

2.81 ± 0.80

19.6

+119.6

Mn

20.0 (4.00)

(n = 5)

20.35 ± 0.86

1.8

+101.8

Zn

18.5 (2.80)

(n = 6)

17.10 ± 1.33

7.6

−92.4