Rapid separation of isomeric fluorophenyl nitrones by ultra-performance liquid chromatography coupled with mass...

Chromatographic separation of positional isomers is a complex challenge, particularly for alkaline biologically active molecules. Liquid chromatography (LC) remains vital for analyzing these compounds. This work addresses the challenge of separating o-, m-, and p-fluorophenyl nitrones (FPNs) by developing a rapid and selective UPLC-MS method, with emphasis on green analytical chemistry principles.

The developed UPLC-MS method achieved rapid isomeric separation with a total run time of 5.0 min. Resolved peaks were obtained within 2.5 min at pH 5.5 and pH 8.2, and within 3.5 min for pH 2.2, pH 6.8, and pH 10.2. This was accomplished using isocratic elution on a BEH C18 column with DI water and Acetonitrile as mobile phases. The method was independent of pH (2.2-10.2) and column temperature (25 °C-50 °C), ensuring robust performance. Furthermore, it was cost-effective, with a high degree of selectivity, and was effective in quantitative estimations down to 0.2 ppm and 0.5 ppm, demonstrating industrial scalability within 8 min using a 100 mm column.

This study presents the first report of a UPLC-MS method for rapid isomeric separation of FPNs. By integrating matrix evaluation, validated sensitivity parameters, and application to real fluorination products (naphthol, resorcinol, acetanilide), the method bridges laboratory optimization with real-world analytical needs. The approach is fast, eco-friendly, and cost-effective, providing a scalable solution for both research and industrial applications.