A variety of voltammetric methods have been carried out for determination of brexpiprazole (BRX) using cyclic voltammetry (CV) and two different type anodic stripping methods; differential pulse (AS-DP) and square wave (AS-SWV) at modified carbon paste electrode with gold nanoparticles (AuNPs-CPEs). Additionally, electrochemical impedance spectroscopy (EIS) technique has been utilized for characterization of the different electrodes. Electrochemical oxidation behavior of BRX shows an irreversible anodic peak at 0.88 V versus Ag/AgCl, in Britton-Robinson buffer (BR) at pH 4.0, 50s preconcentration time and −0.5 deposition potential. Rectilinear relationship between the peak current versus concentration was obtained over the ranges of 1.32 × 10 −6 -6.45 × 10 −6 and 1.32 × 10 −7 -6.45 × 10 −7 mol L −1 for AS-DP and AS-SWV respectively. The lowest concentration that can be detected for both for AS-DP and AS-SWV was 3.99 × 10 −7 and 3.32 × 10 −8 mol L −1 respectively; the utilized methods have been devoted adequately for the estimation of BRX in its pure and dosage form.

Two stability-indicating reversed-phase liquid chromatographic methods were developed and validated for the determination of fluorometholone (FLU) in its mixtures with sodium cromoglycate (SCG) and tetrahydrozoline hydrochloride (THZ). The first HPLC method (Method 1) was based on isocratic elution of FLU and SCG along with their alkaline degradation products on a reversed phase C18 column (250 × 4.6 mm id)-ACE Generix 5, using a mobile phase consisting of methanol-water (70 : 30, v/v), pH adjusted to 2.5 using orthophosphoric acid at a flow rate of 1.2 mL min(-1) Quantitation was achieved with UV detection at 240 nm. The second HPLC method (Method 2) was based on isocratic elution of FLU, its alkaline degradation product and THZ on a reversed phase C8 column (250 × 4.6 mm)-ACE Generix 5, using a mobile phase consisting of acetonitrile-50 mM potassium dihydrogen orthophosphate (40 : 60, v/v) at a flow rate of 2 mL min(-1) Quantitation was achieved by applying dual-wavelength detection, where FLU and its alkaline degradation product were detected at 240 nm and THZ was detected at 215 nm at ambient temperatures. Linearity, accuracy and precision were found to be acceptable over the concentration range of 5-50 and 10-500 μg mL(-1) for FLU and SCG (Method 1) and over the concentration range of 5-80 and 5-60 μg mL(-1) for FLU and THZ (Method 2), respectively. Besides, the FLU alkaline degradation product was verified using IR, NMR and LC-MS spectroscopy. The two proposed methods could be successfully applied for the routine analysis of the studied drugs either in their pure bulk powders or in their pharmaceutical preparations without any preliminary separation step.

The electrochemical oxidation of Sotalol (SOT) based on Tetrazolium Blue (TB)/gold nanoparticles (GNPs)‐modified carbon paste electrodes (CPE) have been studied in the presence of sodium lauryl sulphate (SLS). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry and electrochemical impedance spectroscopy (EIS) techniques have all been utilized within this study. GNPs and TB have a synergetic effect‐giving rise to highly improved electrochemical responses and provide an advantageous platform for the basis of an electrochemical sensor with excellent performance. The experimental parameters, electrodeposition time, pH and scan rate have all been examined and optimized. The sensing of SOT via DPV is found to exhibit a wide linear dynamic range of 1.0×10−7–7.5×10−4 M in pH 2. LOD and LOQ were calculated and found to correspond to 2.5×10−8 M and 8.3×10−8 M, respectively. The suggested sensor has been used successfully for SOT determination in pharmaceutical samples and human urine as real samples. Satisfactory recoveries of analyte from these samples are demonstrated indicating that the suggested sensor is highly suitable for clinical analysis, quality control and a routine determination of SOT in pharmaceutical formulations.

Background: A highly sensitive sensor for the electrochemical determination of an antidiabetic drug Linagliptin (LG) was constructed using carbon paste electrode (CPE) modified with iron oxide nanoparticles (Fe 2 O 3 NPs). The electrochemical performance of LG was examined analytically, and some dynamics were considered for the first time. Results: This work indicates that the oxidation reaction of LG on CPE/Fe 2 O 3 NPs is a one electron and one proton process, which is controlled by both diffusion and adsorption. The simultaneous determination of LG with glucose and metformin (MET) was also considered by square wave voltammetry in universal buffer pH 7.4. Experimental results specify a linear relation between LG peak current and its concentration in the range of 0.03 to 86 μg/ml, leading to a detection limit of 8.0 ng/ml. Conclusion: This novel sensor was successfully used to determine LG in commercialized tablets and in spiked urine samples.

Electrochemical techniques were used for estimating xylazine HCl (XLZ) in bulk powder, medicinal manufacturing and human serum. Electro-oxidation of XLZ at carbon multiwalled nanotube (MWCNT), 1-n-butyl-3-methylpyridinium hexafluorophosphate ion crystal (BMH) and sodium dodecyl sulfate (SDS) MWCNT-BMH-SDS electrode in 0.04 M Britton-Robinson buffer (BR) with pH 7.0, was studied in numerous buffer structures and at different pH values. The experimentation and instrumental parameters to assessable commitment of XLZ had been optimized, and a detection limit was observed as 4.80 nM. The precision and accuracy for the recognized method was tested by retrieval studies with good repeatability and reproducibility of the estimated method. The projected method was practiced successfully to the dosage form and spiked serum.

Two simple, selective and precise stability-indicating reversed-phase liquid chromatographic methods were developed and validated for the determination of mometasone furoate in two binary mixtures, with formoterol fumarate (Mixture 1) and salicylic acid (Mixture 2). Also, a forced degradation study of mometasone furoate was carried out including acid and alkali hydrolysis, oxidation, thermal and photo-degradation. For mixture 1, the method was based on isocratic elution using a mobile phase consisting of (Acetonitrile: 3 mM Sodium lauryl sulfate) (60:40, v/v) at a flow rate of 1 ml min À1 . Quantitation was achieved applying dual wavelength detection where mometasone furoate and its degradation products were detected at 247 nm and formoterol fumarate and its degradation product were detected at 214 nm at 30°C. For mixture 2 and for the forced degradation study, separation was based on isocratic elution of mometasone furoate, its degradation products and salicylic acid on a reversed phase C8 column using a mobile phase consisting of acetonitrile:water:methanol:glacial acetic acid (60:30:10:0.1, v/v) at a flow rate of 2 mL min À1 . Quantitation was achieved with UV detection at 240 nm. In addition, products from alkaline forced degradation of mometasone furoate were verified by LC-MS. Linearity, accuracy and precision were found to be acceptable over the concentration range of 10-800 lg mL À1 and 5-60 lg mL À1 for mometasone furoate and formoterol fumarate, respectively and over the concentration range of 5-320 lg mL À1 and 20-1280 lg mL À1 for mometasone furoate and salicylic acid,

T HE REACTIONS of Rose bengal reagent (Rbeng) with three antifungal drugs Fluconazole (FLZ), Voriconazole (VRZ) and Butoconazole nitrate (BTZ) had been studied for the development of simple, rapid, sensitive spectrophotometric methods for micro-determining of these drugs in pure and in their dosage forms. This method is based on the formation of ionpairs between the drugs and Rbeng reagent. The spectra of the formed ion pairs were measured at pH = 6.5 for FLZ and pH = 6 for VRZ at 575 nm. The spectra of the formed ion pair for BTZ was measured at pH = 4 and at 580 nm. All solutions spectra are measured at selected optimum temperature 20-30 o C. Beer's law was valid in the concentration ranges 30.63-76.57, 34.93-97.81 and 14.2-45.1 μg ml-1 with recovery of (98.00-101.9, 97.92-102.2 , and 98.20-101.3 % for FLZ, VRZ and BTZ, respectively. The values SD = 0.1210-0.4148, 0.4365-1.018 and 0.0748-0.4362, RSD =0.1790-1.152, 0.5248-1.648 and 0.3314-1.011%, the Sandell sensitivity (S) = 0.063, 0.076, 0.017 μg cm-2 , LOQ = 8 , 12.96, 13.27 μg ml-1 and LOD =2.6, 4.4, 4.3 μg ml-1 were calculated for FLZ, VRZ and BTZ, respectively. The results obtained revealed accuracy, precision and sensitivity of the suggested procedures. These methods were applied for analysis of these drugs in their pharmaceutical formulations. The results obtained were found to be in good agreement with those given by official methods, as evaluated by Fand t-tests.

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