Separation and Determination of Fe(III) and Fe(II) in Natural and Waste Waters Using Silica Gel Sequentially Modified with Polyhexamethylene Guanidine and Tiron

Table 1

RSD for determination of iron concentration per 0.1 g of SiO₂-PHMG-Tiron (n = 5).

Added, μg	Found, μg	RSD, %
0.10	0.09 ± 0.01	9.1
0.20	0.21 ± 0.02	6.2
0.50	0.50 ± 0.02	4.0
1.0	1.00 ± 0.04	3.2
5.0	5.1 ± 0.3	4.5