Fluorometric Detection of Five Nitrogen-Based Pharmaceuticals Based on Ion-Pairing Association with EY: DFT Calculations

Fluorometric method for detecting of five nitrogen-based drugs concentration based on inhibition of emission Eosin Y (EY). The selection of N-drugs comprised indapamide (INDP), clomipramine hydrochloride (CMI), promethazine hydrochloride (PMH), lisinopril (LSP), and trifluoperazine hydrochloride (TFPH). The Stern–Volmer style was plotted between relative emissions of EY vs. N-drugs concentration. The standard curves were linear over the concentration range of 5–50 µg mL−1 with R2 > 0.9, and the LOD for INDP, CMI, PMH, LSP, and TFPH were 2.07, 1.36, 3.02, 3.52, and 2.09 µmol·L−1, respectively. The binding constant Kapp for LSP was greater than other N-drugs. Furthermore, the suggested method was hence applied for the routine detection of the concentration of N-drugs in bulk and tablet or syrup dosage forms. FTIR analysis and the electron-mapping density provided the chemical affinity of N-drugs towards EY.