First-derivative spectrofluorometric method based on plasmon-enhanced gold nanoparticles for rapid and ultrasensitive determination of loratadine and pseudoephedrine in human plasma and pharmaceutical dosage forms.

Loratadine (LOR) and pseudoephedrine (PSE) are widely used in combination for the treatment of seasonal allergies; therefore, the development of sensitive and reliable analytical methods for their simultaneous determination is essential. In this study, highly sensitive first-derivative spectrofluorimetric method was developed for the first time to resolve the severe spectral overlap between LOR and PSE. Sensitivity was further enhanced through the incorporation of gold nanoparticles (AuNPs). LOR and PSE were selectively determined at 459.6 nm and 466.0 nm following excitation at 230.0 nm and 226.0 nm, respectively. Methanol was used as the diluting solvent with a short shaking time of 10 min after AuNPs addition. Under the optimized conditions, the method showed linear ranges of 0.8-3.5 ng/mL and 70.0-400.0 ng/mL, with detection limits of 0.26 ng/mL and 31.75 ng/mL, for LOR, and PSE; respectively. The proposed method was successfully applied for the determination of LOR and PSE in human plasma with a recovery of 99.60 ± 0.61 and 99.00 ± 0.89 and in pharmaceutical dosage forms with a recovery of 99.78 ± 1.18 and 99.83 ± 0.15; respectively.