2. How to identify and measure residual solvents?

2.1 General methods

• Weight loss

  Historically, this was the first method to appear in pharmacopoeias. It can be performed either at atmospheric pressure or under reduced pressure. It is, of course, a very easy method to implement, particularly in the context of routine control, but it does have a number of disadvantages:

  • lack of specificity;

  • product consumer (1 to 2 g);

  • limit of quantification (LOQ) of around 0.1%;

  • atmospheric humidity may affect results.

  With the development of thermogravimetric analysis (TGA), the detection limit has been improved...