ISO 1952:1976

Brown coals and lignites — Method of extraction for the determination of sodium and potassium soluble in dilute hydrochloric acid

The sample of brown coal or lignite is extracted with boiling 0,005 N hydrochloric acid and the extract centrifuged. The sodium and potassium in solution are determined by any precise analytical method (for example, gravimetric method or flame photometric method).