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7.6 ACID-INSOLUBLE ASH

7.6 ACID-INSOLUBLE ASH

         Use Method I unless otherwise indicated in the monograph.

Method I

         Boil the total ash for 5 minutes with 25 ml of dilute hydrochloric acid, collect the insoluble matter on an ashless filter paper, wash with hot water until the filtrate is neutral, and ignite at about 500º. Calculate the percentage of acid-insoluble ash with reference to the air-dried substance.

Method II

         Place the total ash or the sulfated ash, as directed in the monograph, in a crucible, add 15 ml of water and 10 ml of hydrochloric acid, cover with a watch glass, and boil for 10 minutes; allow to cool. Collect the insoluble matter on an ashless filter paper, wash with hot water until the filtrate is neutral, ignite to dull redness (550º to 700º), cool in a desiccator and weigh. Reheat until the difference between two successive weighings is not more than 1 mg. Calculate the percentage of acidinsoluble ash with reference to the air-dried substance.

APPENDICES • 7.6 ACID-INSOLUBLE ASH
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หมายเหตุ / Note : TP II 2011 PAGE 518