Green electrochemical and chromatographic quantifications of the extremolyte ectoine in halophilic bacterial cultures and related pharmaceutical preparations

The realistic implementation of electrochemistry into bacterial biosynthesis monitoring programs has always been a challenging task. In this study, two simple, rapid, selective, and sensitive potentiometric sensors were developed and optimized for quantitative analysis of the extremolyte / osmoprotector ectoine (ECT) in halophilic bacterial cultures and also in its related pharmaceutical products. The developed sensors were a Polyvinyl chloride membrane sensor (ECT-PVC) and a coated graphite sensor (ECT-CG). They were established based on the ion association complex of ectoine cation with phosphotungstic acid (ECT-PTA) counter anion as ion exchange site using dioctyl-phthalate (DOP) as a solvent mediator or plasticizer. The sensors exhibited fast, stable, selective, and linear Nernstian responses over a broad range of concentrations ranging from 1 x 10(-5) to 1 x 10(-2) M of the studied drug. The developed sensors were optimized and cross-validated with a proposed HPLC method according to ICH guidelines. The proposed methods were successfully employed to quantify the studied drug in three different types of halophilic bacterial cultures and in an ectoine nasal spray pharmaceutical product. The selected bacteria species were Chromohalobacter salexigens, Halobacillus halophilus, and Halomonas elongata. The proposed methods were statistically compared with the reported methods, demonstrating no significant difference with respect to accuracy and precision. Greenness and environmental impact were also evaluated for the proposed procedures, verifying that they were excellent green and eco-friendly analytical methods.

Automated summary

In this study, two simple, rapid, selective, and sensitive potentiometric sensors were developed for quantitative analysis of a extremolyte/osmoprotector, ectoine, in bacterial cultures and pharmaceutical products. The sensors exhibited fast and linear responses over a broad range of concentrations. The proposed methods were optimized and cross-validated with a HPLC method, showing no significant difference in accuracy and precision. The proposed procedures were also evaluated for their greenness and environmental impact, and were found to be excellent eco-friendly analytical methods.