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Nickel analysis

I am in process of developing a method for measuring Nickel in a water solution the way that it was written by Billie J. Page - Cleveland Heights, Ohio on   (letter 51474). However this solution content Sulfide and some organic fatty acid. The pink color of nickel complex with nioxime reagent can not be reveal until I adjust the pH at the end to pH 7-8. I am afraid that this is not the right pH and I am not getting the right concentration of Nickel this way.

Do you have any suggestion? Can we take care of negative interferences such as sulfide and fatty acids?

Thanks a lot.

Julia Ghani
- South El Monte, California

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Carbon filter your sample. James Watts
- Navarre, Florida

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Mr. Watts' suggestion about carbon treating the sample will probably help a great deal. Just be careful, because the metal impurity content in many activated charcoals is usually not controlled and may be high. Nickel sulfide has low solubility at pH 5, so I assume the sulfide you refer to is either complexed or not ionic. If it is complexed, boiling in a dilute sulfuric or hydrochloric acid should eliminate its interference by removing it as hydrogen sulfide, assuming cadmium, antimony, arsenic and mercury are absent. If it is not ionic, then Carbon should work. Some Carbons contain traces of silver and may help with even the complexed species. Acid treatment followed by carbon treatment and filtration may remove the interference. Be sure to adjust for any acidity you employ with dilute caustic, so that the pH is buffered correctly.

Billie J. Page
- Cleveland Heights, Ohio