Authors:M. Crevar-Sakač, Z. Vujić, Z. Vujčić, B. Marković, and D. Vasiljević
A simple and sensitive liquid chromatography—tandem mass spectrometry method was developed for the quantification of atorvastatin, ortho-hydroxyatorvastatin, para-hydroxyatorvastatin, and atorvastatin lactone in rat plasma. Solid-phase extraction was used for preparation of samples. Rosuvastatin was chosen as an internal standard. Chromatographic separation was achieved on ZORBAX Eclipse C18 Analytical, 4.6 × 100 mm (3.5 μm) column with a gradient mobile phase composed of acetonitrile and 0.1% acetic acid, at a flow rate of 400 μL min−1. The column was kept at constant temperature (25 °C), and autosampler tray temperature was set at 4 °C. The following selected reaction monitoring (SRM) transitions were selected: (m/z, Q1 → Q3, collision energy) atorvastatin (559.47 → 440.03, 22 eV), atorvastatin lactone (541.36 → 448.02, 19 eV), ortho-ohydroxyatorvastatin (575.20 → 440.18, 20 eV), para-hydroxyatorvastatin (575.54 → 440.18, 20 eV), and rosuvastatin (482.25 with selected combination of two fragments 257.77, 31 eV, and 299.81, 35 eV) in positive ion mode. The method was validated over a concentration range of 0.5–20 ng mL−1 for ortho-hydroxyatorvastatin and para-hydroxyatorvastatin and 0.1–20 ng mL−1 for atorvastatin and atorvastatin lactone with excellent linearity (r2 ≥ 0.99). This method demonstrated acceptable precision and accuracy at four quality control concentration levels. The detection limits were 0.1 and 0.13 ng mL−1 for orth-ohydroxyatorvastatin and para-hydroxyatorvastatin, respectively, and 0.05 ng mL−1 for atorvastatin and atorvastatin lactone. All analytes were found to be stable at examined conditions. Validated method was applied for determination of atorvastatin and its metabolites in plasma of experimental animals.
Authors:T. Trtić, L. Vuksanović, S. Paranos, S. Petrović, Z. Vujčić, I. Plećas, and R. Jankov
One of the frequent causes of pollen allergy in our region (Serbia, Yugoslavia) is the pollen of poplar (Populus canadensis). The aim of this study was to form RAST for the determination of specific anti-Populus canadensis IgE antibodies. Affinity purified and radiolabelled (I-125) MoAb E1 was used for forming assay for the determination of specific IgE. By titration of extract of poplarPopulus canadensis we determined that the quantity of 0.65 mL extract is needed for coupling of lg BrCN activated paper discs. Coupling was performed in Na2CO3/NaHCO3 buffer pH 10, on 4°C for 48h. Using this newely formed RAST, specific forPopulus canadensis, we have deteminated anti-Populus canadensis IgE antibodies as well as cross reactivity between pollens ofPopulus canadensis andPopulus deltoides.