This standard specifies three determination methods for the content of hexamethylenetetramine in phenolic resin. These three methods are equivalent. The Kjeldahl method specified in Chapter 3 is not applicable to phenolic resins containing other nitrogen compounds. The perchloric acid method and hydrochloric acid method specified in Chapters 4 and 5 are not applicable to phenolic resins containing other acidic or alkaline substances. If the resin contains additives that can be oxidized by perchloric acid, only the hydrochloric acid method specified in Chapter 5 can be used.