Jasmina Grbović Novaković

Simultaneous capillary gas chromatographic determination of cyproterone acetate and ethynylestradiol in pharmaceuticals

Abstract The simultaneous capillary gas chromatographic determination of non-derivatized cyproterone acetate and ethynylestradiol in pharmaceuticals is described. Chromatographic determination was perfomed on a flexible WCOT quartz column (10 m × 0.25 mm I.O.), coated with a chemically bonded, non-polar CP-Sil 5 CB liquid phase (Chrompack). A split/ splitless injector and a flame-ionization detector were used. Mestranol was used as an internal standard. The total analysis time was 5 minutes. The method is sensitive and reliable and may be applicable in the analysis of these compounds in drug testing.

Experimental and Theoretical Investigations of Cured and Uncured Disiloxane Bisbenzocyclobutene Thin Films

The main challenge in the large-scale commercial applications of benzocyclobutene (BCB) dielectrics is to perform their curing rapidly and efficiently at low temperatures, and in the same time, to obtain large area, high quality, pinhole free dielectric thin films. For that purpose, we investigated numerous uncured and cured BCB films, approximately 2 µm thick, spin-coated on glass/ITO surface, using optical and AFM microscopy, infrared (IR) and Raman spectroscopy, and complete these results with appropriate Linear Combination of Atomic Orbitals (LCAO) calculations. That way we relate microscopic characteristics of the involved molecules, and macroscopic properties of the cured and uncured polymers, which is important for their practical applications.

In-situ and Real-time Monitoring of Mechanochemical Preparation of Li2Mg(NH2BH3)4 and Na2Mg(NH2BH3)4 and their Thermal Dehydrogenation

For the first time, in situ monitoring of uninterrupted mechanochemical synthesis of two bimetallic amidoboranes, M2 Mg(NH2 BH3 )4 (M=Li, Na), by means of Raman spectroscopy, has been applied. This approach allowed real-time observation of key intermediate phases, and a straightforward follow-up of the reaction course. Detailed analysis of time-dependent spectra revealed a two-step mechanism through MNH2 BH3 ⋅NH3 BH3 adducts as key intermediate phases which further reacted with MgH2 , giving M2 Mg(NH2 BH3 )4 as final products. The intermediates partially take a competitive pathway toward the oligomeric M(BH3 NH2 BH2 NH2 BH3 ) phases. The crystal structure of the novel bimetallic amidoborane Li2 Mg(NH2 BH3 )4 was solved from high-resolution powder diffraction data and showed an analogous metal coordination to Na2 Mg(NH2 BH3 )4 , but a significantly different crystal packing. Li2 Mg(NH2 BH3 )4 thermally dehydrogenates releasing highly pure H2 in the amount of 7 wt.%, and at a lower temperature then its sodium analogue, making it significantly more viable for practical applications.