It is proposed that an interlaboratory comparison is done to validate the performance for methods used for CL determination by Australian domestic and overseas facilities. An interlaboratory comparison is a recognised way to understand, as well as validate, a method’s performance, which can be assessed using a consensus value approach where the measured results of the test materials of each particular method is compared to an assigned value (whether the mean or median of test results, or reference result) using statistical analysis (eg z-test).