Vivaspin 15r 5000 mwco hydrosart tubes

The EE% of NLCs was determined with an indirect method. The clear aqueous phase of the NLCs was separated by centrifugation in Vivaspin 15R 5000 MWCO Hydrosart tubes (Sartorius, Stonehouse, UK) with Hermle Z323K, (HERMLE Labortechnik GmbH, Wehingen, Germany). Centrifugation was performed at 5000 rpm (9000 rcf), for 30 min at 4 °C.
The DXM content of the filtered solution was examined by high-performance liquid chromatography (HPLC) (Shimadzu Nexera X2 UHPLC, Kyoto, Japan), which was equipped with a C18 reverse-phase column (Phenomenex Kinetex EVO C18, Phenomenex, Torrance, CA, USA) with dimensions of 1.7 µm, 100 Å, 100 × 2.1 mm. The mobile phase was water:acetonitrile 75:25 in isocratic elution, and the detection was made at 240 nm. The injection volume was 5 µL and the flow rate was 0.5 mL/min. The column temperature was 40 °C. The time of analysis was 6 min and the retention time for DXM was 3.5 min.
The following equation was used to calculate EE% (Equation (4)): $EE \%= \frac{W_{initial drug}-W_{free drug}}{W_{initial drug}}\ast 100.$

The entrapment efficacy (EE%) of the NLCs was determined with this method. The clear aqueous phase of the NLCs was separated by centrifugation in Vivaspin 15R 5000 MWCO Hydrosart tubes (Sartorius, Stonehouse, UK) with Hermle Z323K, (HERMLE Labortechnik GmbH, Wehingen, Germany). Centrifugation was performed at 5000 rpm (9000 rcf) for 30 min at 4 °C.
The DXM content of the filtered solution was examined by HPLC (Shimadzu Nexera X2 UHPLC, Kyoto, Japan), which was equipped with a C18 reverse-phase column (Phenomenex Kinetex C18, Phenomenex, Torrance, CA, USA) with dimensions of 2.6 µm, 100 Å, 150 × 4.6 mm. The separation was evaluated with gradient elution with the following program: time (min)/% of acetonitrile: 0/35, 4.0/60, 4.01/35, 6.0/35, and the detection was made at 240 nm. The injection volume was 5 µL and the flow rate was 1 mL/min. The column temperature was 40 °C. The time of analysis was 6 min and the retention time for DXM was 3.6 min.
The following equation was used to calculate EE% (2): $EE \%=\frac{W_{initial drug}-W_{free drug}}{W_{initial drug}}\times 100$