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A reproducible, sensitive, and cost-effective spectrofluorimetric method has been developed for quantification of the drug ibrutinib in bulk and in its oral capsule formulation. The method was validated in accordance with the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and robustness. The method was found to be extremely sensitive, and excellent linearity was noted within the concentration range 0.1–7.5 μg/mL with a correlation coefficient (r2) of 0.9961. The LOD and LOQ values for the proposed method were found to be 0.224 and 0.680 μg/mL, respectively. Excellent recoveries of the drug were observed from the marketed capsule formulation by the proposed method (97.59, 1.42% relative standard deviation). [ABSTRACT FROM AUTHOR]

A rapid, sensitive, cost effective and reproducible first-order derivative spectrophotometric method was developed for the estimation of gefitinib in bulk and in its marketed formulation. Preliminary spectrophotometric determination of the drug was carried out in acetate buffer pH 2.8 and in 0.1 N HCl with a total of 20 parametric variations. The selected method with three parametric variations employing peak–zero (P–0) and peak–peak (P–P) techniques was assessed for stability indicating potential in force degraded solutions. The developed method was validated with respect to linearity, accuracy, precision, and robustness. Linearity was observed in the concentration range of 5–50 μg/mL with an excellent correlation coefficient (r2) of 0.999. The limits of assay detection values were found for the range from 1.69–3.75 μg/mL, and quantitation limits ranged from 5.11–12.71 μg/mL for the proposed method. The proposed method was applicable for the determination of the drug in its marketed tablet formulation, and percentage recovery was found for the range from 97.42 to 98.58%. [ABSTRACT FROM AUTHOR]

A reproducible, sensitive, and cost-effective spectrofluorimetric method has been developed for the quantification of azelastine hydrochloride in its bulk and nasal formulations. The stability-indicating potential of the method was assessed by recovery studies in the forced degraded solutions of the drug. The method was validated in accordance with the ICH guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and robustness. Excellent linearity was noted in the concentration range 2.0–40.0 μg/mL with a correlation coefficient (R2) of 0.9961. The limits of detection and quantitation for the proposed method were found to be 0.1598 μg/mL and 0.4845 μg/mL respectively. Excellent recovery of the drug was obtained from the proposed method in the nasal spray formulation of the drug (96.5, 0.66% RSD). The stability-indicating potential of the method was assessed from recovery studies of the drug from various forced-degraded samples spiked with known drug concentrations. The studies indicated a high rate of degradation in alkaline, oxidative, and photolytic stress degraded solutions. [ABSTRACT FROM AUTHOR]

We present the results of a comparative analysis of the optical properties of metallic nanoparticles that allows us to select their parameters for effective applications. The optical properties of several metallic (Ni, Ti, Pt, Zn, Mo, and Pd) monodisperse nanoparticles of radii 25 nm, 50 nm, and 75 nm were theoretically studied and analyzed in the spectral range 200-2500 nm. We studied the influence of the nanoparticle parameters (type of metal, radius and concentration of the nanoparticles, etc.) and the surrounding liquid (water) on the optical absorption cross section, scattering cross section, and extinction cross section for absorption, scattering, and extinction of radiation by the nanoparticles. We have established that titanium, nickel, and to a lesser extent molybdenum nanoparticles of radii ~75 nm can be used for efficient absorption and extinction of solar radiation by heterogeneous liquids. [ABSTRACT FROM AUTHOR]

Curcumin is a medicinally important phytoconstituent of curcuminoids. The present study describes development of a simple method for estimation of curcumin in rat plasma. This method involves the use of spectrofluorimetry for evaluation of curcumin at 257 (Ex) and 504 nm (Em). Sample preparation involves only two steps: extraction of curcumin and drying the extract. Following this procedure, the samples are reconstituted with ethyl acetate, and relative fluorescence intensity is measured using a spectrofluorimeter. The method was validated as per CDER guidelines. The linearity of the method was found to be in the range of 100-500 ng/mL with accuracy and precision lying within 2% RSD. The LOD and LOQ were found to be 15.3 and 46.1 ng/mL, respectively. The method was applied for pharmacokinetic evaluation in rats, and AUC, C, and T were found to be 5580 ± 1006 h × ng/mL, 1526 ± 209 ng/mL, and 2.97 ± 0.28 h, respectively, with a plasma half-life of 1.14 ± 0.27 h. [ABSTRACT FROM AUTHOR]

We have developed a very efficient sample preparation procedure for samples of petroleum products using surfactants to extract copper followed by sonication. In order to plot the calibration curve in atomic absorption and inductively-coupled plasma atomic emission determination of copper, we use copper acetylacetonate, allowing us to make the calibration solutions as close as possible in chemical composition to the analyte samples and to improve the precision and accuracy of the determinations. [ABSTRACT FROM AUTHOR]

We consider special features of luminescence and its excitation on exposure of condensed substances to nanosecond beams of electrons with an energy of 100–300 keV at a peak power density exceeding 3·106 W/cm2. This kind of luminescence (iephluminescence) is excited in the absence of dynamic equilibrium between the electrons injected into the substance and leaving it. The depth of a brightly luminescing layer is an order of magnitude larger than the depth of penetration of electrons into the substance. The basic mechanism underlying the excitation of the impurity centers of luminescence in this layer of the substance is the radiative recombination of electron–hole pairs on impurity ions without a change of the ion charge. We show that the iefluminescence encompasses the positive qualities of electro , x ray, photo , and cathodoluminescence. The high brightness and informativeness of the spectrum of iephluminescence allows the use of the latter for a fast nondestructive analysis of a substance. [ABSTRACT FROM AUTHOR]

Spectral characteristics of samples of transformer oil that differ in technical grade, service life, and content of an antioxidant additive and dissolved water are investigated. It is suggested to determine service deterioration of insulating oils from absorption in the region 1710 cm−1 using IR filter analyzers. [ABSTRACT FROM AUTHOR]

This study is carried out to investigate the effect of different plasticizers on characteristics of IR spectra of cellulose acetates. It is found that processes of intermolecular interaction between macromolecules of the polymer and molecules of plasticizing materials result in a shift of absorption bands of acetate groups and in changes in attenuation indices for absorption bands of plasticizers and residual hydroxyl groups in the polymer. The deviation of both the positions of frequencies and attenuation indices is determined by the type and concentration of the plasticizer and by the content of bound acetic acid in cellulose acetate films. [ABSTRACT FROM AUTHOR]