Application of ion mobility mass spectrometry and theoretical calculation in the analysis of sulfonamide antibiotics

Abstract

Sulfonamide antibiotics (SAs) are a class of synthetic antibacterial drugs that are widely used in clinical treatment and the food industry. However, long-term overuse of SAs can increase bacterial resistance and pose potential risks to human health and the environment, so their accurate analysis is crucial. In this study, a quick and effective method for five SA isomers separation was developed by ion mobility mass spectrometry (IM-MS) and theoretical calculations. Three different crown ethers, 18-crown-6 ether (18C6), 15C5, and 12C4 were served as the separation reagent to non-covalent interact with the SAs to form the corresponding binary complexes, and the mass spectrum intensity of the complexes is [SA+ 18C6 +H]⁺> [SA+ 15C5 +H]⁺>[SA+ 12C4⁺H]⁺. Specifically, the SA isomers can be baseline separated by the formed binary complexes, which the separation resolution (R_p-p) can reach 1.672, and the separation effect was 18C6 > 15C5 > 12C4. Quantum chemical calculations were performed for the complex ions of [SA+ 18C6 +H]⁺, revealing the different modes of the 18C6 interactions between the SA isomers, resulting in their conformational differences and mobility separation. Additionally, quantitative analysis for SA isomers by the method was established, effective linearity (R²>0.99) and acceptable sensitivity (0.271 nmol·mL⁻¹) were obtained. Finally, the method was successfully applied to determine of the SA isomers in practical samples of drug tablets and animal liver, with recoveries ranging from 76.43 % to 97.74 %. The results showed that this method was a good choice for the accurate analysis of SA isomers in complex samples.