Hi all,
NT Labs say their ammonia test results are expressed as nitrogen content rather than concentration of ion. If I want the concentration of ion I have to multiply by 1.12.
I assume it is just nitrogen content of NH3, although it should be 1.21, rather 1.12?
It is worked out from the RAM of nitrogen (N) = 14 and hydrogen (H) = 1, so the RMM of NH3 = (14 + 3) = 17 and 14/17 = 1.214. (NH4+ would be "
multiply by 1.29"). These tests usually add an acid to convert all the TAN to ammonium (NH4+), because dissolved gases are problematic to measure. If it adds a base (usually NaOH) it will convert all the NH4+ to NH3.
I am plugging the test result into the free ammonia calculator I found <"
here">.
This does something slightly different from the way you want to use it, it tells you
what proportion of the Total Ammoniacal Nitrogen (TAN) is as dissolved ammonia gas (NH3). It should give you the same result as the table below.
TAN comprises NH3 ("un-ionized" and toxic to aquatic life) and the ammonium (NH4+) ion ("ionized" and relatively benign). The proportion of the TAN that is ionized or un-ionized is <"
dependent upon temperature and pH">
.
cheers Darrel