This part of ISO 7393 specifies a titrimetric method for the determination of free chlorine and total chlorine in water. Sea water and waters containing bromides and iodides comprise a group for which special procedures are required. The method is applicable to concentrations, in terms of chlorine (Cl2), from 0,0004 to 0,07 mmol/l (0,03 to 5 mg/l) total chlorine and at higher concentrations by dilution of samples. For concentrations above 0,07 mmol/l, ISO 7393-3 can also be used. In annex A a procedure is presented for the differentiation of combined chlorine of the monochloramine type, combined chlorine of the dichloramine type and combined chlorine in the