Little_Ghost_again
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Having trouble with nitrate test kits
Hi
I have several aquariums, one in particular is a planted dutch tank and uses CO2 injection for enhanced plant growth.
I use a aquarium test test to measure the nitrate levels and other stuff. If gets expensive testing with these kits as the aquarium runs so well it
eats up the nutrients at a huge rate, so I add in ferts etc.
I need to test often tomake sure the nitrate levels etc are correct.
I found the MSD for the aquarium test kits, but got to thinking........... A company called sparkfun do a small unit that detects colour and gives you
a voltage based on this, now it would be pretty easy to use a micro to read a test tube detect the colour and have a LCD give you the nitrate or
nitrite reading.
But Even with the msd sheets I cant work out how to replicate the kit.
For example Nitrite
the test kit data sheet for bottle one
http://www.regulatory-info-hsx.com/pdf/english/MSDS-A7826.pd...
for the second bottle you use
http://www.regulatory-info-hsx.com/pdf/english/MSDS-A7827.pd...
they give you a little container and you add 5ml water to test tube then add 5 drops from bottle 1, next you add 5 drops from bottle 2 and wait two
mins, the colour is then compared on a chart, obviously instead of the chart I am aiming to do this electronicaly.
But my problem is the msd is a bit vague about whats in the bottles.
For example it say bottle 1 contains Sulfanilic acid conc 0.1%-1%
Hydrochloric acid 1%-5%
Bottle 2
1,2propanediol 60%-100% ??
Acetic acid 10%-30%
N-(1-nNaphytal-Ethyllendiamine Dihydrochloride
So I am not sure exactly what proportions of each chemical are in the bottles, once I know that I could copy it and just work out how much was in a
drop by measuring it. No idea what the chemicals cost but has to be way cheaper to buy the chemicals and make my own kits?
Anyone got any ideas on this?
Many thanks
There are others but I wanted to start here. I cant find the link to the light detector but they are cheap and seem to work (I have used one for
something else)
LG
Its not the sensor I will use but its similar to this one for anyone interested
https://www.sparkfun.com/products/10904
[Edited on 13-12-2014 by Little_Ghost_again]
Dont ask me, I only know enough to be dangerous
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IrC
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http://www.ebay.com/itm/TCS230-TCS3200-Detector-Module-Color...
"Science is the belief in the ignorance of the experts" Richard Feynman
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Little_Ghost_again
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Hi
Thanks for that, I have that side covered, I am asking about the chemistry side and what strength of chemicals to use etc
Dont ask me, I only know enough to be dangerous
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nezza
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I had a look at some nitrate test kits a while ago. The best one I found used coarsely ground zinc to reduce nitrate to nitrite which was reacted with
sulfanilic acid in HCl to give a diazonium salt. This is then added to alpha naphthol in alkali to give a red colour. I modified the test and use this
as a method myself :-
Test for nitrate (NO3-)
Principle
In acid solution nitrate is reduced to nitrite by zinc and hydrochloric acid. This is used to diazotise aniline or sulfanilic acid. This then reacts
with alpha naphthol to give a red coloured diazo dye.
Reagents
Hydrochloric acid (4N) containing sulfanilic acid or
Hydrochloric acid (4N) containing aniline
Coarsely powdered zinc
Alpha naphthol in ethanol
Sodium hydroxide (6N)
Method
1. Add 3 drops of the acid to 4ml of test solution.
2. Add a small spatula of zinc powder.
3. Leave for 2 minutes mixing occasionally.
4. Add 1 drop of alpha naphthol.
5. Add 4 drops of 6N Sodium hydroxide.
The development of a pink-red colour indicates the presence of nitrate in the water. A control of deionised water should be run at the same time.
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Little_Ghost_again
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Quote: Originally posted by nezza  | I had a look at some nitrate test kits a while ago. The best one I found used coarsely ground zinc to reduce nitrate to nitrite which was reacted with
sulfanilic acid in HCl to give a diazonium salt. This is then added to alpha naphthol in alkali to give a red colour. I modified the test and use this
as a method myself :-
Test for nitrate (NO3-)
Principle
In acid solution nitrate is reduced to nitrite by zinc and hydrochloric acid. This is used to diazotise aniline or sulfanilic acid. This then reacts
with alpha naphthol to give a red coloured diazo dye.
Reagents
Hydrochloric acid (4N) containing sulfanilic acid or
Hydrochloric acid (4N) containing aniline
Coarsely powdered zinc
Alpha naphthol in ethanol
Sodium hydroxide (6N)
Method
1. Add 3 drops of the acid to 4ml of test solution.
2. Add a small spatula of zinc powder.
3. Leave for 2 minutes mixing occasionally.
4. Add 1 drop of alpha naphthol.
5. Add 4 drops of 6N Sodium hydroxide.
The development of a pink-red colour indicates the presence of nitrate in the water. A control of deionised water should be run at the same time.
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Hi will this give a quantitative result? or just indicate yes/no for nitrate?
Dont ask me, I only know enough to be dangerous
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blogfast25
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That's very neat, nezza.
What's the estimated detection limit? Would it be suitable for photometric determinations?
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nezza
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Hi folks. It reacts down to 10 or so ppm of nitrate. As for how quantitative it is higher concentrations do give a deeper colour but I suspect a set
of standards would have to be run with any unknowns. The absorption max with sulfanilic acid is about 550nm. Other phenols can be used in alpha
naphthol is not available. Thymol gives an orange colour but is not as sensitive.
[Edited on 14-12-2014 by nezza]
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