ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: Stew_822 on July 24, 2014, 10:36:45 am
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Hi guys,
This is a little way off topic, but I was wondering if it would be possible to measure the concentration of ammonia in water using an automated procedure - that I could make, DIY style, using a raspberry pi as a controller.
I figure IR or uv-visible spectroscopy would be the things to look into. Is that correct? Which one would be preferable if any? I am interested in finding the concentration of ammonia, nitrite, nitrate and possibly macro and micro nutrients. I have searched for ammonia probes but they are $300+ and require replacement of the membranes (something I would very much like to avoid).
The water I would be testing is from an aquarium and so will obviously contain other (unknown) substances. Would these interfere with the result? For example (using the IR method), there would be nitrates in the water - am I correct in reasoning that if I chose a specific wavelength to test for ammonia (that it absorbs strongly in) and the nitrates also absorb in that wavelength, then I will have a skewed reading because I will actually be measuring the concentration of ammonia and nitrate? Likewise, this could possibly be circumvented by using the aquarium water to add ammonia to and produce standards from, but since the nitrate level rises over time in an aquarium I would have to redo the samples frequently, and then if I created a sample from tank water that contained ammonia then you can see that I wouldn't be able to detect ammonia - because I am comparing a sample of tank water to a sample that I think has zero but actually may be 0.25ppm.
So to summarise my main questions:
1) Is it even possible? If so, what technique to measure the concentration would be best?
2) Would the other substances in the aquarium interfere with the result? How can I combat this?
3) Is there an easier way that I have missed?
4) How accurate do you reckon I could get it? Ideally I would like a 0.05ppm detection, but I would settle for 0.1ppm or 0.25ppm. Some fish die at 0.25ppm concentrations though so if I couldn't get it that accurate it would end up being a project mostly for sh!ts and giggles - but all my projects end up like that anyway!
I ain't too good at chemistry, so forgive any errors and stuff.
Cheers,
Stewart