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]. Aspirin, which is widely used in medicine, remarkably reduces the risks of cardiovascular events and death. Aspirin has excellent antiplatelet functions and powerful vascular endothelial protection effects [ 6–10 ]. The mechanisms by which aspirin protects

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A simple, precise, and accurate HPTLC method has been established for simultaneous quantification of aspirin, atorvastatin calcium and clopidogrel bisulphate in the bulk drug and in a capsule dosage form. Chromatographic separation of the drugs was performed on aluminium foil plates precoated with silica gel 60 F254, with toluene-methanol-formic acid 6.5:3.5:0.1 (v/v) as mobile phase. Densitometric evaluation of the separated zones was performed at 254 nm. The three drugs were satisfactorily resolved with R F ± SD values 0.26 ± 0.01, 0.47 ± 0.01, and 0.78 ± 0.01 for aspirin, atorvastatin calcium, and clopidogrel bisulphate, respectively. The method was validated for linearity, specificity, accuracy, precision, and robustness, in accordance with ICH guidelines. Results from recovery studies indicated acceptable recovery of the drugs from the capsule dosage form. The intra-day and inter-day relative standard deviations were in the ranges 0.17–0.73% and 0.46–1.03% for aspirin, 0.36–0.87% and 0.44–0.62% for atorvastatin calcium, and 0.25–0.69% and 0.35–0.94% for clopidogrel bisulphate. The method proved to be a rapid and cost-effective quality-control tool for routine simultaneous analysis of aspirin, atorvastatin calcium, and clopidogrel bisulphate in the bulk drug and in a capsule formulation.

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Molar heat capacities (C p,m) of aspirin were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 383 K. No phase transition was observed in this temperature region. The polynomial function of C p,m vs. T was established in the light of the low-temperature heat capacity measurements and least square fitting method. The corresponding function is as follows: for 78 K≤T≤383 K, C p,m/J mol-1 K-1=19.086X 4+15.951X 3-5.2548X 2+90.192X+176.65, [X=(T-230.50/152.5)]. The thermodynamic functions on the base of the reference temperature of 298.15 K, {ΔH TH 298.15} and {S T-S 298.15}, were derived. Combustion energy of aspirin (Δc U m) was determined by static bomb combustion calorimeter. Enthalpy of combustion (Δc H o m) and enthalpy of formation (Δf H o m) were derived through Δc U m as - (3945.262.63) kJ mol-1 and - (736.411.30) kJ mol-1, respectively.

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An isocratic reversed-phase liquid chromatograpic assay method was developed for the quantitative determination of atorvastatin and aspirin (ASP) in combined dosage form. A Phenomenex Gemini C-18, 5-μm column with mobile phase containing 0.02 M potassium dihydrogen phosphate-acetonitrile-methanol (30:30:40, v/v/v) adjusted to pH 3 using o-phosphoric acid was used. The flow rate was 1.0 mL min−1 and effluents were monitored at 240 nm. The retention times (RTs) of atorvastatin calcium (ATV) and ASP were 10.5 and 3.8 min, respectively. ATV and ASP stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation, and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their RT values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision, and robustness. The method was successfully applied to the estimation of ATV and ASP in combined capsule dosage forms.

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Electron spin resonance spectroscopy was used to investigate the radiation damage in a powder of 2-acetoxybenzoic acid (Aspirin). Three types of radicals occur by -irradiation of Aspirin at room temperature. Two of them are the result of hydrogen abstraction while the third is produced by hydrogen addition at one of the carbon atoms of the ring. The relative yielding of the free radicals as a function of absorbed dose in the range of 2.4 kGy to 160 kGy is also discussed.

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Instrumental neutron activation analysis (INAA) was applied to assess trace element concentrations in six samples of aspirin tablets acquired in São Paulo city, Brazil. Concentrations of the elements Br, Ca, Co, Cr, Fe, K, La, Na, Sc and Zn were determined. Comparisons were made between the results obtained with published data for aspirins from foreign countries. Certified reference materials, INCT-MPH-2 Mixed Polish Herbs were analyzed for quality control of the analytical results.

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Twenty five trace and minor elements (aluminium, arsenic, barium, bromine, cerium, chlorine, cobalt, chromium, cesium, europium, iron, hafnium, potassium, magnesium, manganese, sodium, rubidium, antimony, scandium, selenium, strontium, thorium, titanium, vanadium and zinc) in five different Egyptian aspirin brands (Aspo, Askin, Aspocid, Aspeol and Rivo) have been determined by instrumental neutron activation analysis. It has been concluded that the concentration of arsenic, barium, bromine, cobalt, chromium, iron (except in Aspocid), magnesium, manganese, rubidium, selenium, strontium and zinc in the Egyptian brands is below or within the concentration range reported for these elements in 16 American aspirin and aspirin-like brands.

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A simple, sensitive, accurate, and precise high-performance thin-layer chromatographic method has been established for simultaneous analysis of atorvastatin calcium, ramipril, and aspirin in a capsule dosage form. The compounds were separated on silica gel with methanol-benzene-ethyl acetate-glacial acetic acid 0.36:5.6:4.0:0.04 ( v / v ) as mobile phase. Ultra-violet detection was performed at 210 nm. The R F values were approximately 0.38, 0.06, and 0.86 for atorvastatin calcium, ramipril, and aspirin, respectively. The method was validated for linearity, accuracy, precision, limits of detection and quantification, and robustness. The linearity ranges were 100–600 ng per band for atorvastatin calcium, 50–300 ng per band for ramipril, and 500–3000 ng per band for aspirin. Mean recoveries were 99.97 ± 0.07%, 100.01 ± 0.10%, and 100.02 ± 0.06 % for atorvastatin calcium, ramipril, and aspirin, respectively. Limits of detection (LOD) were 4.88 ng for atorvastatin calcium, 2.91 ng for ramipril, and 18.63 ng for aspirin. Salicylic acid ( R F :_ 0.72) was found as an impurity in the capsule dosage form. The proposed method can be used for analysis of these drugs in combined dosage forms.

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A new, simple, accurate, and precise high-performance thin-layer chromatographic (HPTLC) method has been developed for the separation and simultaneous estimation of aspirin and omeprazole. Standard and sample solutions of aspirin and omeprazole were applied to aluminum foil silica gel G 60 F254 HPTLC plates. The plates were developed with ethyl acetate-dichloromethane-glacial acetic acid 8:2:0.1 (V/V) as the solvent system. HPTLC detection was performed densitometrically at 241 nm. The linear range was 160–960 ng per band for aspirin and 80–480 ng per band for omeprazole, and the correlation coefficients (R 2) were 0.991 and 0.998, respectively. The limits of quantification (LOQ) were 31.89 and 8.01 ng per band, respectively, and the respective limits of detection (LOD) were 10.53 and 2.64 ng per band. Analysis of standard solutions revealed that precision and repeatability were good for both compounds studied.

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Complexes of nickel(II), copper(II) and zinc(II) with aspirin have been prepared. Examination of the complexes of nickel(II) and zinc(II) indicates that they are salicylato complexes in which the aspirin has been de-ethanoylated.

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