Turn-on fluorescence of mirabegron for its sensitive detection in human plasma: Box-Behnken-Design for optimization.

Here, a novel fluorescence strategy was established for the detection of mirabegron (MBG) sensitively on the basis of hantzsch dihydropyridine synthesis. The developed method adopts turn-on fluorescence of MBG for the first time, permitting its selective determination in spiked human plasma at 486 nm after excitation at 410 nm. The developed method exhibited a good linear range from 0.5 µgmL-1 to 2.0 µgmL-1 with detection and quantification limits of 0.05 and 0.2 (µgmL-1), respectively. The profitable applicability of the developed method in spiked human plasma samples was demonstrated, achieving limit of detection below the previously levels reported by spectroscopic methods, allowing application of the developed method for selective determination of MBG in its tablets and spiked human plasma samples with good recovery.

Tuning fluorescence of dapoxetine by blocking of photoinduced electron transfer (PET): Application in real human plasma.

Photoinduced electron transfer (PET) is the most common mechanism proposed to account for quenching of fluorophores. Herein, the intrinsic fluorescence of dapoxetine (DPX) hydrochloride is in the "OFF" state, owing to the deactivation effect of PET. When the amine moiety is protonated, the fluorescence is restored. Protonation of the nitrogen atom of the tertiary amine moiety in DPX leads to "ON" state of fluorescence due to hindrance of the deactivating effect of PET by protonation of the amine moiety. This permits specific and sensitive determination of DPX in human plasma [lower limit of quantification (LLOQ) = 30.0  ng mL - 1 ]. The suggested method adopts protonation of DPX using 0.25 M hydrochloric acid in anionic micelles [6.94 mM sodium dodecyl sulfate (SDS)] leads to a marked enhancement of DPX-fluorescence, after excitation at 290 nm.