Spectrofluorometric determination of calcium in the human nasal secretions investigating the association with olfactory function.

Ionic microenvironment of the nasal secretions especially calcium ions play essential role in the olfactory transmission. However, there is a critical need to determine the free calcium levels in healthy people's nasal secretions in contrast to those of patients with olfactory impairment. A selective spectrofluorometric method was created to quantify nasal calcium levels utilizing its quenching ability to the fluorescence of the functionalized carbon quantum dots. The surface of carbon quantum dots was functionalized with calcium ionophore A23187 and ion association complex, calcium phosphotungstate, to improve the selectively to quantify calcium ions. The functionalized carbon quantum dots exhibited a concentration-dependent fluorescence quenching upon interaction with calcium ions. Different factors influencing the quenching process were done to provide efficient analytical process. The new method, demonstrated accurate calcium determination over the concentration range of 200-4000 ng/mL. The suggested technique was used to measure the calcium in the nasal secretions of both healthy people and patients with olfactory impairment. The findings revealed significantly higher calcium levels in the patient with olfactory dysfunction (healthy vs. patient; 735 ± 20 ng/mL vs. 2987 ± 37 ng/mL, p < 0.05).

A fluorescence chemo sensor approach for determination of finerenone in pharmaceutical formulation and human plasma: Method development and validation.

Finerenone, a non-steroidal mineralocorticoid receptor antagonist, has gained recent approval for treating cardiovascular and kidney-related conditions. Herein, an innovative fluorescence chemo sensor was developed for the determination of finerenone in the pharmaceutical dosage form and the plasma matrix. The method is basically based on chemical transformation of finerenone into a fluorescent product through sequential reactions. This transformation occurs through a sequence of steps involving the interaction of finerenone with trimethylamine, resulting in the formation of a nucleophilic intermediate that subsequently reacts with bromoacetyl bromide to form fluorescent product, (S)-N-(2-bromoacetyl)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxamide. The formed fluorescent product exhibits defined emission peak at 338 nm when excited at 248 nm. Significant concentration-dependent fluorescence enhancement was obtained enabling precise finerenone determination in the pharmaceutical formulation and plasma matrix. The method was optimized and validated providing sensitive determination over linearity range of 1-200 ng/mL with a lower limit of detection at 0.280 ng/mL. This strategy provides an efficient, economical substitute and straightforward, more sensitive analytical method for finerenone assessment in various matrices, in contrast to the previously published method, high-performance liquid chromatography-tandem mass spectrometry, which is expensive and time-consuming.

Application of a nucleophilic substitution reaction for spectrofluorimetric determination of aripiprazole in pharmaceutical dosage form and plasma matrix; greenness assessment.

Aripiprazole is an antipsychotic medicine used to treat a variety of mental disorders, including irritability linked with autism disorder in children. Herein, a green and highly sensitive spectrofluorimetric method was developed for the determination of aripiprazole in pharmaceutical dosage form and plasma matrix. The method based on the formation of a fluorescent adduct from the nucleophilic substitution reaction of 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-chloride) with aripiprazole, which can be detected at 542 nm following excitation at 481 nm. Factors that affect the development and fluorescence sensitivity of the reaction product were investigated and optimized. The reaction yielded the most optimal fluorescence responses when it was performed using 1.5 mL of 0.2 % w/v NBD-chloride, 1.5 mL of borate buffer pH 9, heating at 80 °C for 20 min, and ethanol as a diluting solvent. The method was validated as per ICH guidelines for analytical and bioanalytical procedures. Good linearity was established between the fluorescence responses of the reaction product and aripiprazole concentrations in the range of 100-1200 ng/mL with adequate accuracy and precision results. The applied method was very sensitive and selectively determined aripiprazole in pharmaceutical and plasma matrices with no interferences. Furthermore, the compliance of the proposed method with the principles of green analytical chemistry was evaluated in comparison with the reported method using analytical eco-scale and AGREE metrics. The outputs proved that the proposed method complied more with the principles of green analytical chemistry than the reported method.