Determination of volatiles in pharmaceutical certified reference materials

This work compares the results obtained for the determination of volatiles (water and residual solvents) in new certified reference materials (CRM) or candidate CRMs of the active pharmaceutical ingredients (API) captopril, metronidazole, sodium diclofenac, potassium diclofenac and furosemide, by means of different techniques: loss on drying (LOD), Karl Fischer (KF) coulometric titration, static headspace gas chromatography with flame ionization detection (sHS-GC-FID) and with mass spectrometry (sHS-GC-MS), thermogravimetric analysis (TGA) and near infrared spectroscopy (NIR) with multivariate chemometric analysis of results. The first three methods led to complementary results. The two other techniques were not sufficiently sensitive to determine volatiles in the concentration range evaluated. The loss on drying method was considered the most appropriate to determine the mass fraction of the volatiles to be used in the mass balance calculation of the API mass fraction in the pharmaceutical CRMs.