Quantitative Monitoring the Anti-Solvent Crystallization and Storage Process for Nandrolone by Near-Infrared...

A novel hydrate (S_H2O) of nandrolone was prepared by anti-solvent methods. The crystallization processes with 2 schemes (A and B) were monitored by in-line near-infrared (NIR) spectroscopy. The amounts of S_H2O in powder samples obtained by the anti-solvent crystallization and storage process were quantified by NIR combined with chemometrics methods. In-line NIR spectra from 4500 to 8000 cm^-1 were chosen to capture physicochemical changes during the whole crystallization process. The combination of the principal component results with offline characterization (scanning electron microscopy, powder X-ray diffraction, NIR) data showed that both schemes yielded high purity S_H2O products, but the crystallization speed of scheme B was significantly accelerated. It was demonstrated that in-line NIR spectroscopy combined with principal component analysis can be very useful to monitor in real time and control the anti-solvent crystallization process. Moreover, the solubility and the solid-state transformation of nandrolone under different storage conditions were investigated. The apparent solubility of S_H2O was 2.19-2.44 times of Form I, and S_H2O was relatively stable when stored at a high relative humidity and temperature below 25°C.