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Copper and Iron content in the fiber

Test for  Iron on the fiber:

Reagents: Nitric Acid 5% or 10% w/w Analytical grade.

                  Potassium Thiocyanate Solution 10% w/w made 

                  by dissolving 10 g

                  Potassium thiocyante in 90 gram distilled water

                  Potassium bisulphate, analytical grade.

                  Hydrogen peroxide 35% w/w.

A small sample 0.5 to 1.0 gram of fiber is placed on a watch glass and then spotted with 1-2 drops of nitric acid (5%) and allowed to stand for 2-3 minutes so that any iron present is oxidized to ferric ions. To detect ferric ions, 2 to 4 drops of potassium thiocyanate (10%) are added.

If no color forms then no iron is present. A red color indicates iron is present and the intensity of the color indicates the amount. A pink color indicates low concentrations and a wine red color high concentrations.

Potassium Ferrocyanide test:

A small sample of fabric on a watch glass is spotted with dil Hydrochloric acid(10%). The acidified area of the fabric is then spotted with dil.Pot.ferrocyanide (1% solution freshly prepared). A dark blue color indicates the presence of iron.

Test for Copper:

Copper tetramine test:

The fabric sample is properly ashed using an oven and the cooled ash is spotted with 5 to 10 drops of nitric acid (10%) or hydrochloric acid or by melting with pot.bisulphate.

Add dil. Ammonia (1:1) until the ash is alkaline. A blue color shows the presence of copper. A white background e.g. a sheet of paper helps in observing the shade changes.