I'm using the old standard method.
1 liter water sample
Add 10 mL of 20% sulfuric acid to lower pH.
Add 10 mL of 10% potassium iodide
Titrate with 0.1 N thiosulfate to faint yellow
Continue titrating to colorless.
mL of 0.1 N thiosulfate x 3.55 = total chlorine
Should I be worried about only testing for total chlorine?
What about combined chlorine? Is CC a rare issue?
I found this about using spectrum analyzer.
2. Idiometric Analysis
This is the method of choice where the application requires control of the specific forms of combined chlorine, such as water chloramination monitoring and control (See ChemScan Application Summary # 86, Water Chloramination Process Control). This method is based on the principal that free and combined chlorine will proportionally liberate free iodine from potassium iodide. Free iodine has a strong UV absorbance signature, such that a full spectrum analyzer like the ChemScan UV-2150 can be used to detect the liberated iodine, plus compensate for other oxidizing or reducing agents or interferences in the background (including monochloramine - which can be independently detected), and calculate the resulting concentration of total chlorine. This is also the method of choice if multiple sample lines are being monitored or if other parameters are analyzed in addition to total chlorine. Typical range is 0.05 mg/l to 10.0 mg/l, but can be altered based on path length selection.
Any info or opinion on this method?
Thanks for any comments.