The full evaporation technique: a promising alternative for residual solvents analysis in solid samples

The static headspace technique is the most common approach to residual solvent analysis in pharmaceutical and environmental matrices. This paper presents an alternative tool where the volatile impurities are released from the matrix by working directly on a small amount of sample at a high equilibration temperature: the so-called Full Evaporation Technique (FET). The capability of this method was evaluated on a mixture of nine solvents, which belong to Class 3 in the classification of the European Pharmacopoeia Agency for residual solvents, at various levels of concentration: ethanol, acetone, 2-propanol, methyl acetate, 2-butanone, ethyl acetate, tetrahydrofuran, 2-methyl-1-propanol, 1-butanol. Data on linearity, accuracy, precision and sensitivity are reported. Use of an internal standard proved to be necessary when using such a method. The method is then successfully applied to the analysis of solvent traces in permethylated beta-cyclodextrin.