Practical investigations

Read our general notes on Risk Assessment

I want to investigate the amount of iron in energy drinks e.g. Lucozade, Powerade etc. However, after looking for some guiding practicals, which would help me invent mine, I didn't really find anything that could be done in a school lab! After looking at some of the investigation to do with measuring the amount of iron in iron tablets, I thought I could adapt it to mine. I just want to know if I'm on the right track and if not what is the right track with my investigation !
100408

Jenkin writes:
 
You have two main difficulties. The first is that ‘iron tablets’ contain a lot of iron; they are essentially tablets of iron(II) sulphate. Energy drinks, on the other hand, contain low concentrations of iron; after all, they are not intended to be major dietary sources of iron or even iron supplements.
 
The second difficulty is that ‘iron tablets’ contain Fe²⁺, which reacts with MnO₄^- ions in the standard titration used in the analysis. I don’t know whether the drinks contain Fe²⁺ or Fe³⁺, but I suspect it’s the latter, in which case there would be no reaction with MnO₄^-.
 
One possibility might be to try the reaction with potassium thiocyanate, KCNS, or ammonium thiocyanate, NH₄CNS. These reagents produce a deep, intense red colour in the presence of Fe³⁺ ions, so I suggest you first of all try testing a sample of the drink with a solution of one of them to see if Fe³⁺ is present. If it is, you should be able to devise a colorimetric method to find the concentration of Fe³⁺. You would need to prepare a series of standard solutions of Fe³⁺ (ammonium iron(III) sulphate would be suitable) and use them to calibrate your colorimeter. The concentrations of these solutions would need to be comparable to the Fe³⁺ concentration in the drink, so you would need to do some preliminary work, using ‘naked eye’ comparisons.
 
You could also try testing for Fe²⁺ using potassium hexacyanoferrate(III) solution. This reagent (previously called potassium fericyanide) gives a dark blue precipitate (Prussian blue) in the presence of Fe²⁺, but can’t easily be used quantitatively.
 

Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website. For further guidance see our tutorial on Risk Assessment.

back to Practical investigations

---

Rate this page or react
Share your views on this page, 0 ratings so far

---

updated: 11 April 2008