There are some interferences to consider: Arsenate and silicates above 20 ppm will cause a false reaction. These will form a yellow color. Fluoride, chlorides, and nitrites above 50 ppm will depress the phosphate reaction [...]
The Phosphate test strip is measuring phosphate (as phosphorous) in ppm. We do not offer a strip that can read as low as ppb.
The Ammonia Leak Detection Cloth is treated with a dilute ethanol solution of bromothymol blue and phenolphthalein (10:1 ratio) and air dried. When dry, the cloth is a yellow-orange color. When exposed to ammonia vapors, [...]
Since the ammonia leak detection cloth is simply measuring pH, any interferences present that create an acidic or alkaline environment competing with the effect of any ammonia gas would interact with the cloth.
The dyes are not bound to the cloth with any special binders. They will wash out. They may also discolor materials they contact.
Let's say you're testing the free chlorine content of 1% bleach, which has a pH of 11.8. If the pH is reduced to 8, for example, will the colorimetric response of the Extra High Level [...]
Various types of sulfites can be used – sulfite, bisulfite, and metabisulfite. Our original color chart was developed to measure sulfite ions in ppm (from sodium sulfite standards), however, we have checked standards and found that [...]
The Chlorine Dioxide 0-500 test strips will react to free chlorine solutions, in fact this is how we check the color chart. Only the Low Level Chlorine Dioxide 0-10ppm has an inhibitor for free chlorine. [...]