10.6084/m9.figshare.9089069.v1 Kaili Chen Kaili Chen Xinjiong Ni Xinjiong Ni Licong Wang Licong Wang Yuhua Cao Yuhua Cao Guangqun Cao Guangqun Cao Evaluation of the stability and the encapsulation efficiency of W<sub>1</sub>/O/W<sub>2</sub> multiple emulsions by electrochemical determination Taylor & Francis Group 2019 Multiple emulsions electrochemical detection encapsulation efficiency vitamin B6 2019-07-25 11:53:36 Journal contribution https://tandf.figshare.com/articles/journal_contribution/Evaluation_of_the_stability_and_the_encapsulation_efficiency_of_W_sub_1_sub_O_W_sub_2_sub_multiple_emulsions_by_electrochemical_determination/9089069 <p>A facile and accurate electrochemical approach was developed to evaluate the stability of water-in-oil-in-water (W<sub>1</sub>/O/W<sub>2</sub>) multiple emulsions and the encapsulation efficiency (EE) for water-soluble active ingredient by W<sub>1</sub>/O/W<sub>2</sub> emulsions. In the present work, vitamin B<sub>6</sub>, a kind of electroactive and water-soluble substance was used as the marker encapsulated in the internal aqueous phase (W<sub>1</sub>). The encapsulation efficiency for vitamin B<sub>6</sub> and the stability of the W<sub>1</sub>/O/W<sub>2</sub> emulsions could be evaluated through electrochemical oxidation of vitamin B<sub>6</sub> in the external aqueous phase (W<sub>2</sub>), rather than in W<sub>1</sub>, where vitamin B<sub>6</sub> isolated by oil membrane. The effects of the electrolyte and electrochemical measurement process on the stability of W<sub>1</sub>/O/W<sub>2</sub> emulsions were investigated. Optical microscope images showed that W<sub>1</sub>/O/W<sub>2</sub> emulsions could be dispersed in the electrolytes solution and stable in electrochemical process. The linear relationships between the peaks current in CV curves and the vitamin B<sub>6</sub> concentration ranged from 9.0 μmol/L to 2.5 mmol/L with a detection limit (S/N = 3) of 2.0 μmol/L. It was testified that only vitamin B<sub>6</sub> in the external aqueous phase in W<sub>1</sub>/O/W<sub>2</sub> emulsions could be oxidized electrochemically. The instability of W<sub>1</sub>/O/W<sub>2</sub> emulsions could be monitored through an increase of the peak current due to vitamin B<sub>6</sub> leaking from W<sub>1</sub> to W<sub>2</sub>. When the total amount of vitamin B<sub>6</sub> was 1.5 wt %, the EE of vitamin B<sub>6</sub> was 86.9 ± 0.59%, and decreased to 72.2 ± 0.43% after two weeks.</p>