ANNEXDETERMINATION OF DICHLOROMETHANE AND 1,1,1-TRICHLOROETHANE
IDENTIFICATION AND DETERMINATION OF MERCAPTOACETIC ACID IN HAIR-WAVING, HAIR-STRAIGHTENING AND DEPILATORY PRODUCTS
5.DETERMINATION (see NB)
5.2.Gas chromatograyhy
5.2.5.Methylation
The methylation is carried out either by in situ preparation (5.2.5.1) or with previously prepared diazomethane solution (5.2.5.2).
5.2.5.1.Methylation in situ
Into the methylation apparatus (5.2.3.2) containing 1 ml of ether (5.2.2.11) introduce 50 μl of solution ‘S’ and methylate by the method (5.2.3.2) with about 300 mg of l-methyl-3 nitro-1-nitrosoguanidine (5.2.2.8). After 15 minutes (the ether solution should be yellow to indicate excess diazomethane) transfer the sample solution to a 2 ml bottle having an airtight stopper. Place in the refrigerator overnight. Methylate two samples simultaneously.
5.2.5.2.Methylation with the previously prepared diazomethane solution
Introduce, into a 5 ml stoppered flask, 1 ml of diazomethane solution (5.2.2.12) then 50 μl of solution ‘S’. Leave in the refrigerator overnight.