3.2. Auxiliary measurements
Absorption spectra were measured using a Shimadzu UVmini 1240 spectrophotometer (Japan) in a quartz cells (path lengths, l = 1 cm and l = 0.1 cm) at room temperature in the wavelength range 190–1100 nm. For weighing, a Kern 770 analytical balance (Germany, precision ±0.1 μg) was used. To intensify the dissolution, a GRAD 38-35 ultrasonic bath (Grad Technology, Russia) was used. Samples were taken with Eppendorf Pro automatic pipettes (Germany), (20 ± 1)–(200 ± 1) μl, (100 ± 1)–(1000 ± 1) μl, and (500 ± 1)–(5000 ± 1) μl.