An Ultrasensitive and Environmentally Benign Synchronous Spectrofluorimetric Strategy for Determining the Anti-Inflammatory (Celecoxib) and the Antidepressant (Citalopram) in Different Matrices

Depression is one of the leading global public health problems. Studies have shown that patients with rheumatoid arthritis are at high risk for depression. In pharmacokinetic studies, determining co-administered medicines is highly important to achieve the best potential therapeutic results. Herein, two co-administered drugs were determined by the second derivative synchronous spectrofluorimetric method in their pharmaceuticals and spiked human plasma; the first was celecoxib and the second was citalopram. Both celecoxib and citalopram had a native florescence, but their emission spectra showed a large overlap that complicated their determination by traditional fluorescence, this obstruction could be solved by measuring the synchronous fluorescence at Δλ = 70 nm, then deriving the second derivative allowing separation of celecoxib and citalopram with a zero-crossing point at 347 and 306 nm, respectively. In accordance with ICH instructions, method parameters were validated showing excellent sensitivity of the method, encompassing the concentration interval of 100.0–2000.0 ng/mL and 20.0–900.0 ng/mL for celecoxib and citalopram, respectively. The Green Analytical Procedure Index, Analytical GREEnness Metric approach, and the Green Solvents Selecting tool found that these procedures have a high level of environmental friendliness. In addition, the Blue Applicability Grade Index evaluation tool determined that the suggested technique was workable.