|MadSci Network: Chemistry|
Foods are generally complex materials that require digestion before they can be analyzed for minerals. A chemist would use a spectrophotometer to analyze for aluminum. The process involves heating to such a high temperature that the entire sample is vaporized and the vapors are measured in a spectrophotometer. This machine will read the components of the vapor and print out an analytical "map". This is a very specialized piece of equipment that may not be available to you. You might consider a qualitative method for detecting aluminum to determine whether or not your cooking method would leach aluminum from the cooking vessel into the food. I did find a method for testing for aluminum on a chemistry website from Australia. The website is: http://www.uq.edu.au/%7Exxjelfic/topic12.html#12.10.3 Below is the method proposed for testing for aluminum: 18.104.22.168 Group 3 Test for Al3+, Cr3+, Fe2+, Fe3+ 1.First test. 1.Add 8 drops of NH4Cl solution to 5 drops of the original solution. 2.Test the solution with litmus paper. 3.Add enough drops of dilute NH3 solution to turn red litmus blue. 1.A green precipitate identifies Fe2+ or Cr3+. 2.A red brown identifies Fe3+. 3.A white glassy precipitate identifies Al3+. 4.If no precipitate forms, go to (Group 4 Test). 2.Second test. 1.Add to 5 drops of the original solution 6 drops of NaOH then 2 drops of NaHClO solution boil then add 2 drops of lead(II) ethanoate (lead(II) acetate solution) 2.OR 3.Use lead acetate test paper 1.A yellow precipitate indicates Cr3+. 4.(The following common test is too dangerous to be used in schools because potassium hexacyanoferrate(III) (potassium ferricyanide) reacts with strong mineral acids to release TOXIC potassium cyanide. 5.Add to 5 drops of the original solution 5 drops of K3Fe(CN)6 solution 1.A deep blue precipitate identifies Fe2+. 2.A brown green precipitate identifies Fe3+. Note that the experiments above assume you begin with a liquid. Many food tests start by digesting the food with a strong acid so you have a clear liquid to work with. Also this method does not indicate how much aluminum is present, just whether or not any aluminum is there. I have not worked with this test so I cannot advise you of its practicality. You have a very interesting project idea, good luck! Phyllis Stumbo University of Iowa
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