INVESTIGATION OF TROPICAMIDE AND BENZALKONIUM CHLORIDE STABILITY USING LIQUID CHROMATOGRAPHY

Abstract

In this study, a development of stability indicating method (SIM) that could be used to detect a decrease in the amount of tropicamide and benzalkonium chloride due to their degradation is described. In the method development, stress samples should be used. Benzalkonium chloride proved to be very stable under all stress conditions. Acid stress with 0.1 M HCl at 70°C led to 10% degradation of tropicamide after 30 min. The alkaline stress with 1 M NaOH at 70°C induced faster degradation and more than 20% of tropicamide degraded after 30 min. On the other hand, tropicamide proved to be exceptionally stable to oxidative stress and no degradation was observed with 30% H₂O₂ even after heating at 70°C for 90 min. The mobile phase consisted of acetonitrile and water phase 70:30 v/v (water phase: 5 mM sodium heptan sulphonate and 1% triethylamine – TEA) with pH of the mobile phase adjusted to 3.5 with ortophosphoric acid. The flow rate was 2 mL min⁻¹. In order to confirm the method adequacy for intended purpose, the proposed method was validated. Finally, the proper validation of developed SIM performed according to the official guidelines proved that the method accomplishes its intended purpose.

Keywords:

• benzalkonium chloride
• eye drops
• forced degradation studies
• liquid chromatography
• tropicamide
• validation

ACKNOWLEDGMENTS

The authors thank to the Ministry of Science of the Republic of Serbia for supporting these investigations through the Project 172052.

Notes

r – correlation coefficient; S_b – standard deviation of the intercept.

*S (n = 3).

*S (n = 3).