Method (adapted from APHA Standard Method 3500-Fe B. Phenanthroline Method)1. Ferrous (Fe2+) Iron: - Acidify sample: 2mL conc. HCl per 100 mL sample at time of collection
- Take 50 mL of acidified sample into a 100 mL volumetric flask
- Add 20 mL phenanthroline solution + 10 mL ammonium acetate solution
- Dilute to 100 mL and measure absorbance at 510 nm within 5 - 10 mins
2. Total Iron: - To 50 mL of sample add 2 mL conc. HCl + 1 mL hydroxylamine hydrochloride solution
- Heat sample to boiling and boil to reduce volume to 15-20 mL
- Cool to room temperature and transfer to a volumetric flask
- Add 10 mL ammonium acetate buffer solution + 4 mL phenanthroline solution
- Dilute to 100 mL and measure absorbance at 510 nm
To determine ferric iron in sample, subtract ferrous iron from total iron. Reagents from Labchem
Reagent | Catalog # | Cost | Shelf life | | Hydroxylamine hydrochloride, 10% | LC155301 | $37.80 for 500 mL | 24 months | | Ammonium acetate buffer solution | LC181501 | $33.20 for 500 mL | 12 months | | Phenanthroline solution, 0.1% | LC181501 | $33.20 for 500 mL | 12 months | | Hydrochloric acid, conc. | LC149501 | $27 for 500 mL | | | Iron standard, 200 ppm | LC157207 | $22.90 for 125 mL | 24 months |
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