Division 3.16 Concentrated internal standard solution, c = 2,5 μmol/ml:

In a 500 ml volumetric flask dissolve 0,2728 g α-methyl-tryptophan (3.3) in hydrochloric acid (3.13) and make up to the mark with hydrochloric acid (3.13). Store at - 18 ^oC for a maximum of 4 weeks.