Table 2.

Acidic and Oxidizing Stability Performed in a Ternary Mixture

Stress Factor	Concentration	Time	Temperature	Remaining (%)	Loss (%)
Acid 0.1 M HCl	0.5%	0 h	Room temperature	99	1
		1 h	Room temperature	98	2
		1 h	60 °C	96	4
Oxidant 5 V H2O2	0.6%	0 h	Room temperature	99	1
		2 h	Room temperature	98	2
Temperature	0.5%	2 h	90°C	99	1

Abbreviations: H₂O₂, hydrogen peroxide; HCl, hydrogen chloride; MCE, Methoxypropylamino Cyclohexenylidene Ethoxyethylcyanoacetate.

MCE was solubilized in a 0.5 g/100 ml ternary water/ethanol/isopropanol mixture with the final concentration of 50/40/10 (v/v/v). Duplicates were put in contact with an acidic or oxidizing solution at controlled temperature and time. Aliquoting and analytical follow-up were performed on a UPLC/DAD Acquity apparatus (Waters, Milford, MA). The results showed that MCE is stable to mild acidic hydrolysis and to H₂O₂ oxidizer. This means that MCE could be further integrated into cosmetic galenic support containing water, with adjusted pH lower than neutrality and without any issue regarding the presence of oxygen or oxidizing agent.