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Water-soluble and highly yellow fluorescent carbon dots were synthesized by using sucrose as a carbon source and phosphoric acid as a dehydrating agent. Instrumental techniques such as fourier transform infrared spectroscopy, ultraviolet absorption and fluorescence spectroscopy, and transmission electron microscopy have been employed to characterize the carbon dots. The results indicated that the synthesized carbon dots have spherical shape with mean diameter of 7 nm. The distribution of carbon dots is uniform which emit yellow fluorescence. Fourier transform infrared spectroscopy study revealed the presence of high amount of –OH groups on carbon dots surface. Oxytetracycline quenched the fluorescence of carbon dots via static quenching mechanism. The reduction in fluorescence intensity of carbon dots permitted to design a fluorometric assay for oxytetracycline. The calibration curve (change in fluorescence intensity vs. concentration of oxytetracycline) was linear in the concentration range of 1.0 μg/mL–10.0 μg/mL with a detection limit of 0.33 μg/mL and correlation coefficient of 0.9981. The method was tested to quantify the oxytetracycline in spiked wastewater, milk, and meat samples and gave satisfactory recoveries.

In this study, magnetic inulin/Mg–Zn–Al layered double hydroxide (MILDH) was synthesized for the adsorption of ciprofloxacin. The application of various analytical techniques confirmed the successful formation of MILDH. For the optimization of controllable factors, Taguchi design was applied and optimum values were obtained as equilibrium time─100 min, adsorbent dose─20 mg, and ciprofloxacin concentration─30 mg/L. The highest capacity of the material was recorded as 196.19 mg/g at 298 K. Langmuir model (R2= 0.9669–0.9832) fitted best as compared to the Freundlich model (R2= 0.9588–0.9657), concluded the monolayer adsorption of ciprofloxacin on MILDH. Statistical physics model M 2 was found to fit best to measured data (R2= 0.9982–0.9989), indicating that the binding of ciprofloxacin took place on two types of receptor sites (n1and n2). The multidocking mechanism with horizontal position was suggested on the first receptor site (n1< 1), while multimolecular adsorption of ciprofloxacin lying vertically on the second receptor site (n2> 1) at all temperatures. The adsorption energies (E1= 22.79–27.20 kJ/mol; E2= 18.00–19.46 kJ/mol) illustrated that the adsorption of ciprofloxacin onto MILDH occurred through physical forces. Best fitting of the fractal-like pseudo-first-order kinetic model (R2= 0.9982–0.9992) indicated that the adsorption of ciprofloxacin happened on the MILDH surface having different energies. X-ray photoelectron spectroscopy analysis further confirmed the adsorption mechanism of ciprofloxacin onto MILDH.

This study details the synthesis, characterization and protein binding efficiency of chitosan nanoparticles. Chitosan (CS) supported 1-phenylisatin (1-ph) loaded CS nanoparticles (NPs) (1-ph@CH-PEG/TPP) were synthesized utilizing the inotropic gelation method. The optimization of the composition of CSNPs was done using BBD. These formed CSNPs were then characterized with FTIR, SEM, TEM, TGA-DTA and XRD analyses. The addition of PEG increased the loading efficiency of CSNPs from 45.96 to 94.41% for bare nanoparticles to PEG encapsulated NPs, respectively. The drug encapsulated nanoparticles interacted with the universal protein BSA. The fluorescence quenching results showed that the system statically quenched its fluorescence. For BSA-1-ph and BSA-1-ph@CH-PEG/TPP systems, Ksvvalues decrease with increasing temperature (283–310 K; 6.15 × 104 L mol−1to 1.19 × 104 L mol−1for BSA-1-ph and from 2.52 × 104 L mol−1to 1.09 × 104 L mol−1for BSA-1-ph@CH-PEG/TPP). The binding calculations revealed that the 1-ph@CH-PEG/TPP system showed a decrease in its binding strength to the protein molecule as compared with the pure 1-ph system. This decrease in binding increases the therapeutic effect of the drug molecule and hence the produced CSNPs can be efficiently used as a potential drug delivery system. The UV, synchronous and 3D analysis confirmed the structural alteration of serum after binding. The effect of different metal ions on the binding profile of the 1-ph-BSA system was also investigated. Molecular docking results further validated the experimental finding.

The PVC membrane immobilized with lansoprazole-tungstate and plasticized with dioctyl phthalate was characterized by FTIR, XRD, and SEM. The effects of critical parameters such as response time, pH, and temperature on the potential were analyzed, and these were optimized using central composite design (CCD) and desirability function. Under the optimized conditions, the plot of measured potential against concentration of lansoprazole exhibited linearity from 2 × 10–5to 2 × 10–3mol L–1at pH 4.4. The slope of the plot and detection limit was −41.50 mV/decade and 1.57 × 10–5mol L–1, respectively. The response time of the proposed ion-selective electrode was ≤30 s. The electrode exhibited good selectivity for lansoprazole over a number of ionic species, commonly found in commercial dosage forms. The response mechanism was also discussed. The proposed ion-selective electrode was successfully applied for potentiometric determination of lansoprazole.

AbstractA simple and sensitive spectrophotometric procedure has been developed for the determination of haloperidol in bulk and its formulation/tablets. Method is based on the interaction of carbonyl group of haloperidol with 2,4-dinitrophenyl hydrazine [DNPH]. The condensation reaction produces a red coloured product which absorbs maximally at 456 nm. The effects of variables such as concentration of DNPH, KOH, HCl and the reaction time were investigated to optimize the procedure. Beer’s law was obeyed in the concentration range of 3.6–10.8 μg mL-1 with molar absorptivity of 2.84×104 L mol-1 cm-1. The results were validated statistically as per the ICH Guidelines. The proposed method has been applied to the determination of haloperidol in tablets with satisfactory results. The obtained results are compared statistically with those given by a reference method. The point and interval hypothesis results indicate that the proposed procedure is not biased.

A simple and sensitive spectrofluorimetric method has been developed and validated for the determination of the antidepressant clomipramine hydrochloride in its dosage forms. The method was based on the fluorescent ion-pair complex formation between clomipramine and alizarin red S at pH 1.99. The ion-pair complex showed maximum fluorescence intensity at 561 nm with excitation at 490 nm. Different variables affecting the reaction conditions such as the concentration of alizarin red S, pH, reaction time and the extracting solvents were carefully studied. Under the optimised conditions, the fluorescence intensity was found to be linearly related with clomipramine hydrochloride concentration in the range of 1.0–20 μg ml−1. The detection and quantitation limits were 0.32 and 0.97 μg ml−1, respectively. No interference was observed from the excipients commonly present in dosage forms. The proposed method was successfully applied to the determination of clomipramine in its pharmaceutical tablets with good accuracy and precision; the recovery values were 99.75–100.05%.

A kinetic spectrophotometric method has been developed which is based on the oxidation of pantoprazole with Fe(III) in sulfuric acid medium. Fe(III) subsequently reduces to Fe(II), which is coupled with potassium ferricyanide to form Prussian blue. The reaction is followed spectrophotometrically by measuring the increase in absorbance with time (1-8 min) at 725 nm. The initial rate method is adopted for constructing the calibration graph, which is linear in the concentration range of 5 - 90 μg ml-1. The regression analysis yields the calibration equation, v= 3.467 × 10–6+ 4.356 × 105C. The limits of detection and quantitation are 1.46 and 4.43 μg ml-1, respectively. The proposed method was optimized and validated both statistically and through recovery studies. The experimental true bias of all samples is < ±2.0%. The method has been successfully applied to the determination of pantoprazole in pharmaceutical preparations.

Abstract: To purify a material and remove the excess impurities one should first recognize that whether they are actually present and what their nature is. In the past, this was not always done. But presently drug analysis and pharmaceutical impurities are the subjects of constant review in the public interest. The International Conference on Harmonisation (ICH) guidelines achieved a great deal in harmonizing the definitions of the impurities in new drug substances. It is necessary to perform all the investigations on appropriate reference standards of drug and impurities to get meaningful specifications. In order to meet the challenges to ensure high degree of purity of drug substances and drug products, a scheme is proposed for profiling drug impurity. Finally, analytical methods based on analytical instrumentation must be employed to quantitate drug substance and its impurities. Important aspects and suggestions related to drug analysis and pharmaceutical impurities are discussed.

A simple kinetic spectrophotometric method is described for the determination of famotidine. The method is based on the oxidation of the drug with alkaline potassium permanganate. The reaction is followed spectrometrically by measuring the rate of change of the absorbance at 610 nm. The initial-rate and fixed-time (at 12 min) methods are adopted for determining the drug concentration. The calibration graphs are linear in the ranges of 2–10 pg mL-1and 1–8 pg mL-1using the initial-rate and fixed-time methods, respectively. The method has been applied to the determination of famotidine in tablet formulations. The obtained results are compared statistically with those given by a reference spectrophotometric method.

Abstract. A new spectrophotometric method is described for the determination of verapamil hydrochloride, based on its oxidation with chloramine-T in hydrochloric acid medium. It produces a yellow colored compound with maximum absorbance at 425 nm. Beer's law was obeyed in the concentration range 0-340 µg mL^-1 with molar absorptivity 2×10³ L mol^-1 cm^-1 and RSD 0.3-0.82%. All variables were studied to optimize the reaction conditions. No interferences were observed from the common excipients present in the formulations. The method has been applied successfully to the determination of the drug in pharmaceutical preparations. Statistical comparison of the results with those from the reference method reveals excellent agreement and confirms that accuracy and precision are not significantly different.

The use of 1-chloro-2, 4-dinitrobenzene is described for spectrophotometric estimation of ascorbic acid. The procedure is based on the interaction of ascorbic acid with 1-chloro-2, 4-dinitrobenzene in alkaline medium. The product absorbs maximally at 380 nm and has the molar absorptivity 0.14 × 1041 mole-1cm-1. Beer's law is obeyed in the concentration range 0.12–0.6 mg/10ml of ascorbic acid.

Zirconium(IV) arsenate vanadate was prepared by adding a mixture comprising 0.05 M sodium hydrogen arsenate and 0.05 M sodium metavanadate to an aqueous solution of zirconium(IV) dichloride oxide (0.05 M) in different volume ratios at pH 1. The material possessed a good ion-exchange capacity of 1.20 and 1.30 meq g−1of exchanger for the Na+and K+ion, respectively, and was fairly stable in dilute mineral acids, but insoluble in water, acetic acid, formic acid, ethanol, and 1,4-dioxane. The distribution coefficients of a large number of metal ions were determined in different solvent systems.

An accurate and simple quantitative method for determining levodopa and methyldopa is proposed. Cerium(IV) has been successively used to react with drugs in 2 M H2SO4at 80° C. The absorbance of colored products was measured at 510 and 550 nm for levodopa and methyldopa, respectively. The method has been extended to the determination of these drugs in dosage forms. The results have been statistically compared with those obtained by the reference method.

Zirconium(IV) selenophosphate has been prepared by adding a mixture which is 0.05 M in sodium selenite and 0.05 M in orthophosphoric acid to a 0.05 M solution of zirconium(IV) bis(nitrate) oxide in different volume ratios at pH 1. Its ion-exchange capacity, thermal and chemical stability, pH titration curves, and chemical composition were studied. Adsorption of some of the metal ions in different solvent systems has been studied. The effect of particle size on the sorption behavior of metal ions has also been studied. The analytical importance of this material has been demonstrated by achieving the eleven quaternary separations of metal ions. A comparison of ion-exchange properties of this material has also been made with some other ion-exchangers.

Two simple, sensitive and accurate spectrophotometric methods have been developed for the analysis of perindopril in pharmaceutical preparations. Method A is based on the formation of ternary complex between zinc(II), eosin and the perindopril, which is extractable with chloroform. The absorption spectrum exhibits a band peaking at 510 nm. Method B is based on the interaction of drug with iodine in dichloromethane resulting in the formation of charge transfer complex which absorbs maximally at 365 nm. Beer's law is obeyed in the concentration range 10–200 µg/ml and 10–180 µg/ml with molar absorptivity of 2.25×103 and 3.71×103 l/mol·cm for methods A and B, respectively. The detection limits for methods A and B are 0.49 and 0.90 µg/ml, respectively. The optimum experimental conditions for the proposed procedures are investigated. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference between the methods compared in terms of accuracy and precision.