What is the difference between the 2100Q and 2100Qis models?
2100Q and 2100Qis differences
The 2100Q model uses a tungsten (400-600nm) lamp and is compliant with USEPA method 180.1. The 2100Qis model uses an LED (860nm) and is ISO7027 compliant. Typically US customers will order the 2100Q version, but certain applications are better measured using the LED version (i.e. highly colored samples). Also, the 2100Q reads in NTU, while the 2100Qis reads in FNU; the difference in unit is due to the light source used to measure the sample.