How to identify and measure residual solvents?
Analysis of residual solvents in pharmaceuticals

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 (in some cases, it is possible to obtain a quantification limit of around 100 ppm), as has a significant reduction in product...