There are two protocols generally used for the solubility measuring, the thermodynamic and the kinetic protocol. The first one can be defined as the concentration of compound in a saturated solution when the excess of solid material is in equilibrium with the solution at the end of dissolution process. The kinetic solubility is the concentration of a solution when the first precipitate appears after adding the highly concentraced solution of compound (most often using the dimethyl sulphoxide as a pre-solvent) in the solvent. The main advantage of the kinetic protocol is short time of sample preparation in comparison to the thermodynamical protocol. Although the thermodynamic protocol takes a longer time to reach equilibrium and is difficult to automate, it provides more accurate data because the solvent is not influenced by the other aditives such as dimethyl sulfoxide.
The solubility measuring is performed using chromatographic system (Vanquish UHPLC) connected to the diode array detector and consequently to the charged aerosol detector (both Vanquish); all from Thermo Fisher Scientific, Germany). Samples and calibration standards are prepared using automated system of robotic arm (PAL-RTC, Switzerland). This method is powerful in detecting possible impurities and measuring the solubility of the analyte of interest. The charged aerosol detector is a universal detector for non- and semi-volatile compounds. It also detects analytes with a lack of chromophore, such as steroids and its derivatives.
Contact
Karel Kudláček, ☎ 588
