Simultaneous determination of some antidepressant drugs and vitamin B12 in pharmaceutical products and urine sample using HPLC method.

Three sensitive, accurate and precise HPLC methods were devolved for the simultaneous determination of vilazodone HCl (VILHC), agomelatine (AGO) or duloxetine HCl (DULHC) and vitamin B12 (cyanocoblamine B12) in bulk, pharmaceutical dosage form and in urine samples. Both similar methods (I and II) were carried out using 0.04 M phosphate buffer (pH 7.0), acetonitrile and methanol in the ratio (30:30:40, v/v) as a mobile phase. Thermo BDS hypersil-C18 column, with 5 µm particle size and 250 × 4.5 mm dimensions, at flow rate 1.0 mL min-1 and UV detection at 277 nm at ambient temperature 25 °C were used. The retention times were 5.12 and 2.54 min for VILHC and vitamin B12, 4.98 and 2.53 min for AGO and vitamin B12, respectively, with linearity range from 0.001 to 200 µg mL-1. However, for the separation of DULHC and B12, UV detection at 230 nm and Agilent Eclipse XDA-C8 (150 × 4.5 mm, 5 µm) column, were used (method III). The retention time of DULHC and vitamin B12 was found to be 4.53 and 1.35 min, respectively, with linearity range from 0.0005 to 200 µg mL-1. The proposed methods were validated as per the ICH guideline with very low LOD and LOQ. The values of %RSD for precision was less than 2% and the value of % recovery were found to be 99.20-100.9% and 99.23-100.67% for determination of the drugs in pure and pharmaceutical formulations, respectively, for all methods confirming that the methods are precise, accurate and selective for separation and determination of VILHC, AGO or DULHC from B12 in tablets and in urine samples without any interference from each other or from common excipients.

Role of Green Chemistry in Antipsychotics' Electrochemical Investigations Using a Nontoxic Modified Sensor in McIlvaine Buffer Solution.

A new low-cost green electrochemical sensor based on nontoxic polyethylene glycol (PEG) and silver nanoparticles was used to improve the sensitivity of the carbon paste electrode for the investigation of olanzapine (OLZ) in dosage arrangements and in the existence of its coadministered drug fluoxetine and in the drug formulation. Scanning electron microscopy measurements were carried out to emphasize the morphology of the electrode surface. Cyclic voltammetry and differential pulse voltammetry were used to explore the diffusion and linearity behaviors of OLZ. Impedance spectroscopy measurements were determined to investigate the ac behavior of OLZ and then an ideal electrical circuit was modeled. A linear calibration was obtained from 1.0 × 10-8 to 1.25 × 10-4 M. The limit of detection was 1.5 × 10-9 M, whereas the limit of quantification was 5 × 10-9 M. The way has been wholly authenticated concerning linearity, precision, accuracy, reproducibility, sensitivity, and selectivity.

A novel simple biosensor containing silver nanoparticles/propolis (bee glue) for microRNA let-7a determination.

A novel sensitive electrochemical sensor for microRNAlet-7a detection in normal serum samples, hepatocellular carcinoma patients and human liver cancer cells, has been excellently synthesized. The sensor constructed of carbon paste (CP) amended with silver nanoparticles (AgNPs) and extracted propolis (bee glue). The AgNPs/P modified carbon paste electrode (APCPE) displayed a high electrocatalytic activity in a Britton Robinson (BR) buffer (pH = 7.4). The techniques utilized to prepare this work are square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Surface characteristics were achieved using scanning (SEM), Fourier-transform infrared spectroscopy (FTIR), Spectrophotometer, transmission (TEM) electron microscope, energy dispersive X-ray analysis (EDX) and elemental mapping (EM) techniques. Under optimal conditions, the suggested sensor exhibits good rapid and sensible response reaching a very low detection limit of 10-3 femtomolar.

Novel sensor based on carbon paste/Nafion® modified with gold nanoparticles for the determination of glutathione.

Several problems for the direct electrochemical oxidation of reduced glutathione (GSH) challenge the usage of electroanalytical techniques for its determination. In this work, the electrochemical oxidation of GSH catalyzed by gold nanoparticles electrodeposited on Nafion modified carbon paste electrode in 0.04 mol L(-1) universal buffer solution (pH 7.4) is proved successful. The effect of various experimental parameters including pH, scan rate and stability on the voltammetric response of GSH was investigated. At the optimum conditions, the concentration of GSH was determined using differential pulse voltammetry (DPV) in two concentration ranges: 0.1 × 10(-7) to 1.6 × 10(-5) mol L(-1) and 2.0 × 10(-5) to 2.0 × 10(-4) mol L(-1) with correlation coefficients 0.9988, 0.9949 and the limit of detections (LOD) are 3.9 × 10(-9) mol L(-1) and 8.2 × 10(-8) mol L(-1), respectively, which confirmed the sensitivity of the electrode. The high sensitivity, wide linear range, good stability and reproducibility, and the minimal surface fouling make this modified electrode useful for the determination of spiked GSH in urine samples and in tablet with excellent recovery results obtained.

Determination of morphine at gold nanoparticles/Nafion® carbon paste modified sensor electrode.

A novel and effective electrochemical sensor for the determination of morphine (MO) in 0.04 mol L(-1) universal buffer solution (pH 7.4) is introduced using gold nanoparticles electrodeposited on a Nafion modified carbon paste electrode. The effect of various experimental parameters including pH, scan rate and accumulation time on the voltammetric response of MO was investigated. At the optimum conditions, the concentration of MO was determined using differential pulse voltammetry (DPV) in a linear range of 2.0 × 10(-7) to 2.6 × 10(-4) mol L(-1) with a correlation coefficient of 0.999, and a detection limit of 13.3 × 10(-10) mol L(-1), respectively. The effect of common interferences on the current response of morphine namely ascorbic acid (AA) and uric acid (UA) is studied. The modified electrode can be used for the determination of MO spiked into urine samples, and excellent recovery results were obtained.