Division 6.5 Determination

United Kingdom

1. 6.5.1Division 6.5.1
2. 6.5.2Division 6.5.2
3. 6.5.3Division 6.5.3
4. 6.5.4Division 6.5.4
5. 6.5.5Division 6.5.5
6. 6.5.6Carefully remove the cork or stopper and rinse it and the inside of the neck of the flask with a little of the mixed solvent (4.6.) so that the rinsings run into the flask.
7. 6.5.7Division 6.5.7
8. 6.5.8Rinse the outside of the neck of the extraction flask with a little of the mixed solvent (4.6.), collecting the rinsings in the fat-collecting vessel and taking care that the mixed solvent does not spread over the outside of the extraction flask.
9. 6.5.9Division 6.5.9
10. 6.5.10Division 6.5.10
11. 6.5.11Carry out a third extraction by further repeating the operations described in 6.5.3. to 6.5.8. inclusive, but using only 15 ml of diethyl ether (4.4.) and 15 ml of light petroleum (4.5.); use the ether to rinse the inside of the neck of the extraction flask. If necessary, raise the interface to the middle of the neck of the flask to enable the final decantation of solvent to be as complete as possible.
12. 6.5.12Division 6.5.12
13. 6.5.13Heat the fat-collecting vessel (with the flask placed on its side to allow solvent vapour to escape) for one hour in the oven (5.4.). Remove the fat-collecting vessel from the oven, allow to cool (not in a desiccator, but protected from dust) to the temperature of the weighing room (for glass vessels allow at least one hour, for metal dishes allow at least 30 minutes) and weigh to the nearest 0,1 mg.
14. 6.5.14Division 6.5.14
15. 6.5.15Add 25 ml of light petroleum to the fat-collecting vessel in order to verify whether or not the extracted matter is wholly soluble. Warm gently and swirl the solvent until all the fat is dissolved.
16. 6.5.16If the extracted matter is not wholly soluble in the light petroleum, or in case of doubt, extract the fat completely from the vessel by repeatedly washing with warm light petroleum.