ALS change of Nitrate reporting level

[Garry]

Hi All,
I notice that, due to a required replacement of limits of detection with limits of quantification, the lowest reported level for Nitrate has risen from 0.59mg/l to 2.11mg/l.  Now a result of <2.11mg/l will not quite meet the limit set in 23500-3.  Has anybody resolved with ALS or are other labs reporting in a similar way?

A further question, that may answer the above.   With the standard requiring <2mg/l as N and our ASL results presented as NO3, could anybody reference information as to if there is a conversion that needs to be applied (or are they the same in terms of Nitrate level?)

I’ll run it by ALS as well

Thanks

[Chris Bates]

Hi,
A limit of 2 mg/l of NO3 if reported as Nitrate (N) is equivalent to a limit of 9 mg/l of NO3.
Basically multiply the N limit by 4.5 to get the NO3 limit
Hence the Renal Association limits were 9 mg/l (NO3).
This was spotted by Gareth Murcutt many years ago and Lizzie Lindley concurred.
According to my GCE Chemistry it's all to do with atomic weights

N=14 O=16

NO3 = 14 + 3x16 = 76

NO3/N  = 76/14 = 4.43

[Garry]

Thanks for clarifying.

For further confirmation reference to this can be found in the ‘Clinical Practice Guideline
Prepared on behalf of The Renal Association and The Association of Renal Technologists
January 2016’