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Winkler Method, HELP!

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Hi!

I'm planning on testing the BOD of water for my Chemistry HL IA. My school is missing a chemical called Alkaline Iodide Azide. I asked the school and even did my own research on where to get sodium azide but it seems impossible. Also, the incubator reaches only as low as 32 degrees and room temperature is 25 degrees. I require storing the water at 20 degrees but am still finding solutions to this. 

I thought of using a mixture of potassium iodide and potassium hydroxide with the absence of azide which is required to eliminate nitrite interference with the iodide ions. 

Anyone out there has any tips? Solutions for me? Recommendations? Or can anyone who has done Winkler method help me? Is there also a method to test for nitrite. I thought of testing the water for nitrite as well if my substitute potassium mixture actually works.

Thank You very much!

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15 hours ago, Nicholas said:

Hi!

I'm planning on testing the BOD of water for my Chemistry HL IA. My school is missing a chemical called Alkaline Iodide Azide. I asked the school and even did my own research on where to get sodium azide but it seems impossible. Also, the incubator reaches only as low as 32 degrees and room temperature is 25 degrees. I require storing the water at 20 degrees but am still finding solutions to this. 

I thought of using a mixture of potassium iodide and potassium hydroxide with the absence of azide which is required to eliminate nitrite interference with the iodide ions. 

Anyone out there has any tips? Solutions for me? Recommendations? Or can anyone who has done Winkler method help me? Is there also a method to test for nitrite. I thought of testing the water for nitrite as well if my substitute potassium mixture actually works.

Thank You very much!

I don't want to discourage you, but there's a kid in my year group who did this very same experiment and it ended up as a big failure because the values were more or less consistent for all samples. He had tested 7 different lakes in our town for BOD using the Winkler method. You haven't mentioned how would the samples differ? 

Keep it simple... You see it's too big of a hassle for you to collect all the materials you need, and I'm sure you could think of something else

"I thought of testing the water for nitrite as well if my substitute potassium mixture actually works."

The method for testing this involves methods that are far out of your scope of work. -_-

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