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81.
A simple and rapid method for morphine detection is described based on PEDOT electrode in the presence of SDS. The electrochemistry of morphine is investigated by CV, LSV and SWV. The effect of common interferences on the current response of morphine namely AA and UA is studied. The electrode is applied to the selective determination of morphine in urine samples in the linear ranges 0.3–8 µmol L?1 and 10–60 µmol L?1, with low detection limits of 50 and 68 nmol L?1, respectively and recovery of 96.4 %. The application of PEDOT is realized in determination of morphine in tablets successfully. 相似文献
82.
Hanieh Kargarzadeh Ishak Ahmad Ibrahim Abdullah Alain Dufresne Siti Yasmine Zainudin Rasha M. Sheltami 《Cellulose (London, England)》2012,19(3):855-866
Cellulose nanocrystals (CNC) were first isolated from kenaf bast fibers and then characterized. The raw fibers were subjected
to alkali treatment and bleaching treatment and subsequent hydrolysis with sulfuric acid. The influence of the reaction time
on the morphology, crystallinity, and thermal stability of CNC was investigated. Fourier transform infrared spectroscopy showed
that lignin and hemicellulose were almost entirely removed during the alkali and bleaching treatments. The morphology and
dimensions of the fibers and acid-released CNC were characterized by field emission scanning electron microscopy and transmission
electron microscopy. X-Ray diffraction analysis revealed that the crystallinity first increases upon hydrolysis and then decreases
after long durations of hydrolysis. The optimal extraction time was found to be around 40 min during hydrolysis at 45 °C with
65% sulfuric acid. The thermal stability was found to decrease as the hydrolysis time increased. The electrophoretic mobility
of the CNC suspensions was measured using the zeta potential, and it ranged from −8.7 to −95.3 mV. 相似文献
83.
A promising composite‐modified glassy carbon electrode is fabricated by electrodeposition of mono‐dispersed gold nanoparticles onto carbon nanotubes (AuNPs/CNTs/GCE). The electroanalysis of Tramadol (TRA) was achieved by different electrochemical techniques. The effect of different parameters including pH, concentration and potential scan on the oxidation current signal of TRA was investigated. Large excess of ascorbic acid (AA) and uric acid (UA) with a maximum molar ratio of 1/1000 and 1/100, respectively, did not interfere with the response of TRA. The detection limit with high sensitivity is 68 nM. TRA was successfully determined in pharmaceutical dosage forms, without any pretreatment of the samples. 相似文献
84.
Second derivative spectrophotometry was applied to determine the binding constant (K) between codeine phosphate (COD) and bovine serum albumin (BSA) at simulated physiological conditions (37.00?°C and pH = 7.4). The second derivative spectra of COD in buffer solutions containing various amounts of BSA showed derivative isosbestic points. The residual background signals derived from incomplete suppression of BSA signals can be entirely eliminated in the second derivative spectra indicating that BSA has spectrophotometrically one kind of binding site for COD. The fractions of COD bound to BSA were calculated from the derivative intensity differences (??D values) of COD before and after the addition of BSA. Scatchard plot calculation suggested that the binding of COD to BSA can be explained by a partition-like non-specific binding model. The binding constant (K) was calculated from ??D values according to the non-specific binding model by a nonlinear least-squares method. K values were almost constant for all of the COD concentrations studied with good reproducibility. The fractions predicted by the K values were in good agreement with the observed values. The results indicate the usefulness of the derivative method in drug?Calbumin binding studies without the need for prior separation procedures which may disturb the equilibrium states of the samples solutions. 相似文献
85.
The effect of different antioxidants and their mixtures on the thermal aging and accelerated weathering of γ-radiation vulcanized EPDM rubber in presence of crosslinking coagent, was investigated. The compounds used were either a synergistic blend of phenolic and phosphite antioxidants, i.e. 1:4 Irganox 1076: Irgafos 168 or a blend of arylamine and quinoline type antioxidants, i.e. 1:1 IPPD:TMQ, at fixed concentration. Tinuvin 622 LD hindered amine light stabilized (HALS) was also used. The response was evaluated by the tensile strength and elongation at break for irradiated samples after thermal aging at 100°C for 28 days and accelerated weathering (Xenon test) up to 200 h. 相似文献
86.
Five simple and accurate methods are presented for the determination of terazosin (TZ) in tablets. These methods are based on: the direct measurements of the first and second derivative spectra of samples (A), the reaction of TZ with chloranil (CH) in aqueous solution of pH 9 to give an intense yellow color measured at 340 nm (B), the reaction of the drug with mercurochrome (MER) in aqueous alkaline medium to give an intense red color measured at 543 nm (C), the formation of an ion-pair salt between the drug and bromocresol purple (BCP) with subsequent absorbance measurements at 412 nm (D), and a sensitive fluorimetric method (E). The latter method was extended to determine TZ in presence of its degradation products. 相似文献
87.
Hatem A. Abdel-Aziz Bakr F. Abdel-Wahab Marwa A. M. Sh. El-Sharief Mohamed M. Abdulla 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):431-437
Abstract The reaction of 1-[4-(piperidin-1-yl)benzylidene]thiosemicarbazide with hydrazonoyl chlorides afforded 1,3-thiazole derivatives.
Cyclization of two compounds of the latter 1,3-thiazole by means of bromine in the presence of sodium acetate at room temperature
gave 1,3-thiazolo[2,3-c]-1,2,4-triazole derivatives. The reaction of 2-cyano-3-(4-piperidin-1-ylphenyl)prop-2-enethioamide with hydrazonoyl chlorides
under reflux in ethanol in the presence of triethylamine yielded 1,3-thiazoles. Treatment of 3-oxo-3-(piperidin-1-yl)propanenitrile
with phenyl isothiocyanate in DMF, in the presence of KOH, at ambient temperature, resulted in the formation of 3-anilino-3-mercapto-2-(piperidin-1-ylcarbonyl)acrylonitrile
which was reacted with hydrazonoyl chlorides to yield the corresponding 1,3,4-thiadiazole derivatives. Some of the newly synthesized
compounds had significant anti-arrhythmic activity.
Graphical Abstract
相似文献
88.
The use of Eriochrome Black A for the EDTA titrations of Zn, Mn, Ni, Pb and Cu ions is described. Spot tests for the determination of the sensitivity limits of detection have been made 相似文献
89.
Hala E. Zaazaa Rasha Abdel-Ghany Mahmoud Sayed M. Abdelkawy Shimaa A. Atty 《液相色谱法及相关技术杂志》2020,43(13-14):474-481
AbstractTwo precise and selective stability-indicating RP-LC methods have been developed and validated for simultaneous determination of metolazone in its binary mixture with losartan potassium (method 1) and spironolactone (method 2) in the presence of their degradation products. For method 1, the chromatographic separation was achieved on Kromasil C18 column, the mobile phase consisted of a mixture of 0.1% ortho-phosphoric acid in acetonitrile and 0.1% ortho-phosphoric acid in water (28:72, v/v) pumped at flow rate 2?mL/min and UV detection at 235?nm. Linearity was determined over the concentration range of 2–16µg/mL for metolazone and 40–320µg/mL for losartan potassium. For method 2, chromatographic separation of metolazone and spironolactone was achieved on a Symmetry C8 column using a mobile phase that consisted of acetonitrile, methanol, and 0.1% ortho-phosphoric in water in gradient mode pumped at a flow rate 1.5?mL/min with programed wavelength detection. Linearity was determined over the concentration range of 2–16µg/mL for metolazone and 20–160µg/mL for spironolactone. The suggested methods were proved to be highly selective, precise and accurate for simultaneous determination of the cited drugs in their combined pharmaceutical dosage form in the presence of their degradation products. The proposed methods were validated in compliance with ICH guidelines.
- Highlights
Synchronized determination of metolazone and co-formulated drugs in presence of their degradation products.
Act as a method for screening of metolazone and co-formulated drugs in quality control laboratories.
Validation of suggested methods according to ICH guidelines.
The pathway of degradation of metolazone under different stress conditions was proposed.
90.
A. A. El-Zahhar H. M. Abdel-Aziz T. Siyam 《Journal of Radioanalytical and Nuclear Chemistry》2006,267(3):657-664
Summary The ion-exchange and sorption characteristics of new polymeric composite resins, prepared by gamma radiation were experimentally
studied. The composite resins show high uptake for Co(II) and Eu(III) ions in aqueous solutions in a wide range of pH. The
selectivity of the resins for Co(II) or Eu(III) species in presence of some competing ions and complexing agents (as Na+, Fe3+, EDTANa2, etc.) was compared. Various factors that could affect the sorption behavior of metal ions (Co(II) and Eu(III)) on the prepared
polymeric composite resins were studied such as ionic strength, contact time, volume mass ratio. 相似文献