ISO 6851:2001 (R2021)

This International Standard specifies a method for the determination of the total organic nitrogen, as well as any ammoniacal nitrogen, present in photographic processing wastes by the Kjeldahl method. Total Kjeldahl nitrogen can be determined in photographic processing wastes in the range of 10 mg/l to 200 mg/l as ammonia, or in the range of 8 mg/l to 160 mg/l in terms of nitrogen. If ammoniacal nitrogen (see ISO 6853) is determined separately and subtracted, the concentration of organic amino nitrogen can be established.