After optimization, the HPLC–IMER was compared to a well established distillative method (IFU 7a (International Federation of Fruit Juice Producers (IFU), 2000), which is based on the Monier-Williams Method, but optimized for fruit juices) regarding sulfite recovery rates and standard deviation. The comparison was per-formed by our laboratory, as well as by an official reference laboratory in a DRRR1 proficiency testing.