Macherey Nagel Quantofix ammonium

Macherey-Nagel Quantofix Ammonium test strips. Pkt of 100. Range is 0 to 400 mg/l, gradation 0 - 10 - 25 - 50 - 100 - 200 - 400 mg/l. These strips test for combined ammonia and ammonium nitrogen. In acidic (less than pH 7) solutions less harmful ammonium dominates but as pH rises harmful ammonia levels increase.

At 20 deg C here is the proportion (%) that harmful ammonia makes up of the total ammonia and ammonium: pH 7, 0.4%; pH 7.5, 0.99%; pH 8, 3.83%. Source Lamotte Smart Colorimeter Manual. So take a pH reading when measuring ammonia-N then multiply by the percentage given (interpolate if necessary) to get harmful ammonia.

Keep in mind that the proportion of harmful ammonia increases with temperature. For example between 10 deg C and 20 deg C the proportion of harmful ammonia approximately doubles at the same pH.