Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: curiouscat on July 18, 2013, 01:53:30 AM
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I was reading this pdf document (link below) from the UK environment agency about COD and the Section on Calibration seems wrong to me. In this table below, if I am reading it correctly, 0.938 mg/L of glucose is said to correlate with 1000 mg/L COD.
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FaYZvB4o.png&hash=f8fd15bde26a7a7140a887fa6bd76a5f45a9ca6a)
Barely 1 mg/L seems just too low to give a COD of 1000, seems to my intuition (and some back of the envelope calculations). Is this an error? Should it have been 0.938 gm/L
OTOH the document has a reputable pedigree so I may be the one who's wrong. Just wanted to check what people think.
http://www.environment-agency.gov.uk/static/documents/Research/COD-215nov.pdf
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Looking at table E2 on page 58 and back calulating the weight of sodium acetate trihydrate that contains as much acetic acid as the 508mg mentioned in E2 giving a theortical 542mg/L COD means 2140mg/L sodium acetate trihydrate should give 1000mg/L COD. The same calulation for sodium oxalate and oxalic acid gives 8257mg/l. So yes I thing the values given in the bit you have shown us are wrong and should be g/L.
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Looking at table E2 on page 58 and back calulating the weight of sodium acetate trihydrate that contains as much acetic acid as the 508mg mentioned in E2 giving a theortical 542mg/L COD means 2140mg/L sodium acetate trihydrate should give 1000mg/L COD. The same calulation for sodium oxalate and oxalic acid gives 8257mg/l. So yes I thing the values given in the bit you have shown us are wrong and should be g/L.
Ah! Hadn't noticed that table.
Thanks for verifying this!