Uv 2100 spectrometer

Green Propolis was incorporated into the coacervate gels by imbibition. A 70 µg/mL GP aqueous solution was prepared; after that, hydrogel samples (of ca. 20 mg) were placed in that volume of GP solution and left there for 2 h, at 25 °C, using a thermostatic bath.
The encapsulation (EE) efficiency was calculated by using, respectively, the following equations: $EE=\frac{\left(total amount of GP-nonbound GP\right)}{total amount of GP}\times 100$
To determine the GP release kinetics, the hydrogel samples, after GP encapsulation, were placed in vessels containing 20 mL of water, and kept in an incubator (Labwit, ZWY-100H, Burwood East, VIC, USA), at 37 °C and 150 rpm. At predetermined time intervals (20 min), aliquots of the supernatant were taken from the vessel and stored for GP quantification. Meanwhile, that volume was replaced with water. The process was repeated until release equilibrium was attained. The GP released into the supernatant was quantified spectrophotometrically by measuring the absorbance in a range of 200 to 800 nm using a double-beam Shimadzu UV-2100 spectrometer (SHIMADZU EUROPA, Duisburg, Germany).

All reagents were purchased from commercial suppliers (Merck and Aldrich) and used without further purification. The FT-IR spectra of products were measured in ATR approach by JASCO FTIR-4100 spectrophotometer. The X-ray diffraction (XRD) patterns were recorded by using a Philips Xpert MPD diffractometer with Cu Ka radiation (l = 0.15418 nm). Transmission Electron Microscopy (TEM) was carried out on Philips EM 208S 100KV. Scanning electron microscopy (FE-SEM) images were obtained using a Mira 3-XMU instrument. The UV-vis spectra were recorded on a Shimadzu UV-2100 spectrometer.