NBN EN 14671:2006

This European standard specifies a procedure for the determination of extractable ammonia using a 2 mol/l potassium chloride solution in raw and digested sewage sludges. The range of the method is up to 100 g/kg N assuming appropriate dilution of the potassium chloride extract in the final measurement step.
The above wording will be modified once the round robin results are available. It may be suitable for other types of sludges, but the user should validate the method using these sludges.