Question
Posted on: April 8 2014Crystals in modified sugar-free cough syrup with dextromethorphan from TMF
Answer
I have not yet heard of precipitation in the Dextrometorfansyrup TMF. So I find the problem in the dyes, which you add first to Dextrometorfansyrup TMF
Tartrazine is an after salt and consequently, the dye is an anion; Patent Blue V is an acid and reacts with citric acid with after saccharinate, K sorbate and Na-tartrazine.
Tartrazine:
Patent Blue:
You indicate that the pH of the Final Solution is 4 to 5. So I suppose there are still different anions in the solution, which may react with dextrometorfanH +. On the composition of dextrometorfanhydrobromide syrup TMF, I have to point the finger at tartrazine. If we lower the pH even with citric acid (250 mg?) to 3 to 4 with then the dissociation of tartrazine may be sufficiently reduced and no more crystal formation occurs??