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Standard Method (Adapted)

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 
3. Ferric (Fe3+) Iron

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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