I've noticed that some FAS-DPD chlorine test kits (sold by Taylor and others) utilize Potassium iodide crystals instead of a reagent solution to effect a color change indicating Combined Chlorine (CC) products in a sample. What is the reason for this? Do the crystals provide some additional measure of accuracy over the liquid solution? The kits containing the crystals are generally more expensive. Any thoughts - even conjecture - on this would be appreciated.
Taylor offers two kits dedicated to FAS-DPD chlorine testing:
K-1515 - Uses KI solution (R-0003 DPD Reagent #3)
K-1516 - Uses KI crystals (Potassium Iodide Crystals R-0765)