Salicylate

Salicylate is a type of ammonia test kit which shows you the amount of free ammonia (NH3) in the water. It is generally unaffected by the use of water conditioners (if used quickly) which convert ammonia into ammonium (NH4) or other similar non-toxic types.

This type of test kit is usually a liquid and is preferred by serious aquarists due to this lack of false negatives. They also tend to be more expensive to purchase but last a long time and are cheaper per test.