Zinc Colorimetric Test StripsZinc Test Strips: 0 to 50 mg L Convenient, on site water testing Use for quick spot checks to ensure water quality. These new water test strips are perfect for field testing, process control, and analytical and research applications. Strips are easy to use: simply dip the strip into water sample to be tested, remove strip, and compare resulting color change to enclosed color chart. Tests take approximately 1 to 10 minutes. Strips are packaged 100 pk.