Parameter

# analyzed samples

1

2

3

4

5

6

7

8

Concentration of iron in sample

(absorbance units at 490 nm) × 10³

64

68

55

71

63

65

60

61

Mean value of concentration

63.38

Standard deviation, %

4.93

Coefficient of' variation,%

7.78

Chi-square

2.68

Probability,%

84.77