Macherey-Nagel test strips for nitrate, in 2 presentations covering different measuring ranges.
91351
91366
A semi-quantitative test strip for nitrate, the end product of biological nitrogen breakdown. Dip it, wait the stated time, and compare the pad against the colour scale on the tube.
It is the number that reveals fertiliser runoff in a well, an overloaded aquarium, or a soil that no longer needs nitrogen. Drinking water limits exist because nitrate is dangerous to infants specifically.
A strip gives a range, not a figure. That is enough for the great majority of decisions — dose or do not dose, discharge or hold, keep running or stop — and it gives the answer where the sample is, in about a minute, with no instrument to calibrate and nothing to carry back to a laboratory.
When a number has to be defensible — a regulatory report, a dispute, a limit you are close to — a photometer or a laboratory method is the right tool. The strip's job is to tell you whether you need one.
Results are often quoted two ways — as nitrate or as nitrate-nitrogen. They differ by a factor of about 4.4; check which one a limit refers to before comparing.
Supplied in 2 presentations covering different measuring ranges. The range is chosen by model: 100, 250.