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Ebola: How can free residual chlorine of 0.05% or 0.5% be measured please? A standard Pooltester only measures a few ppmase

Is there any colorimeter or comparator for testing free residual chlorine to ensure that the levels in the handwashing and cleaning solutions in triage and holding facilities are the right level, please? A standard Pooltester can only measure in the low range of a few ppm, so that's not helpful except for drinking water.

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Hi Trish As Robert suggest, the WataTest works well to check chlorine solutions in Ebola context. It has been designed to test a 0,6% solution, so it works for 0,5%. To test 0,05% you just test a 10 time bigger sample. I've tried it myself, it works. Advantages : Antenna technology is already present in Guinea, Liberia and Sierra Leone, and the WataTest is relatively cheap and produced locally.

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Wonderful news Cyril!!! Do you have their contact details in Sierra Leone please?

Trish In Cyberspace gravatar imageTrish In Cyberspace ( 2015-05-02 10:17:55 +0000 )edit

Thanks @Trish In Cyberspace. How to obtain a Watatest kit in Sierra Leone for checking chlorine solutions is now a separate question here: http://ebola.knowledgepoint.org/en/qu...

KnowledgePointAdmin gravatar imageKnowledgePointAdmin ( 2015-05-13 15:35:04 +0000 )edit
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Antenna in Switzerland make a test kit that can test concentrated chlorine solutions in the range needed for ebola treatment centres. see http://www.antenna.ch/en/research/saf.... My experience is that you can dilute as previously described but it's a bit hit and miss. Better than nothing if you are not sure of your HTH supplies.

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Hi Trish,

I am not sure for what purpose you are trying to measure chlorine levels, but I hope this helps... some...

http://www.who.int/water_sanitation_h...

http://waterquality.cce.cornell.edu/p...

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Standard pooltesters use DPD as an indicator, which is not effective above around 10 ppm. To access a higher range you need to use a different chemistry.

For example, Palintest manufacture a chlorine high range test which is effective up to 250 ppm, based on potassium iodide chemistry - this is available in comparator or photometric formats. The range that you mention goes up to 5000 ppm, so you would need to dilute by 20x in order to bring into range.

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I'm not aware of any (accessible) tester in these ranges.

You could test by diluting your solution down to the ppm range using a syringe and a litre of clean water, but the uncertainty on the end result is probably too high to bring any usable information.

My best take on it would be to double check your dosage calculations, use reasonably clean water and containers, use proper chlorine generating products (not expired), and discard the solutions after 24hrs.

The impact of microbiology/chemistry in the water would only be in the ppm range, so the impact on a 0.05% (=0.5mg/L=500ppm) will be minimal (ie: even if 1-2ppm of chlorine get used up when preparing the solution, you'll still be close enough to your target, even more so with 0.5% solutions)

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Hi Trish,

This test strip works in the range you're asking about: http://www.sensafe.com/test-strips/se...

You might also consider a low range color disk test kit, such as this one from Hach: http://www.hach.com/free-chlorine-col...

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Thanks John for your answer. Both of these products are unfortunately unable to measure in the range we require, which is up to 5000 ppm.

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Thanks Robert and Iain!

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There are test strips for doing this usually used for testing pipe disinfection residuals so with a high range. Not massive accuracy but OK for checking the basic level. Lamotte is one US make http://www.lamotte.com/en/blog/test-f...

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Guess this is not easy in some contexts. But it can be done by titration.

Alternatively use a BDH comparator. It has a dulling screen to read up to 4mg/li

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