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of ST 1 and ST 15 the amount of weakly bound water is significantly smaller than that of strongly bound water desorbing at higher temperatures (above 110 °C). The intermediate properties with respect to the proportion of weakly and strongly bound

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DTA profile, Fig. 5 , also shows two exothermic peaks at 389 and 571 °C corresponding to the decomposition of the intermediate species with elimination of 2 HCl and 2(2-APm) molecules, respectively, and formation. [Pd

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. 2014 , 16 , 55 – 62 . 2. For reviews of continuous-flow processes applied in the preparation of natural products and pharmaceutical intermediates: (a) Watts , P. ; Haswell

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Biodiesel from soybean oil, castor oil and their blends

Oxidative stability by PDSC and rancimat

Journal of Thermal Analysis and Calorimetry
Authors: M. B. Dantas, A. R. Albuquerque, L. E. B. Soledade, N. Queiroz, A. S. Maia, I. M. G. Santos, A. L. Souza, E. H. S. Cavalcanti, A. K. Barro, and A. G. Souza

intermediate compositions of the original biodiesel's. This led to linear variations for some physico-chemical parameters, as showed in Table 2 . Table 2 Physicochemical properties of biodiesels and their blends

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intermediate species required for the study. In DSC the sample mass taken for the respective precursors were 6.78, 9.69, 9.47 and 8.25 mg. The respective residual mass of the samples taken after the end of the scanning was 4.04, 3.70, 3.75 and 4.19 mg. The

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A new high-performance thin-layer chromatographic (HPTLC)—densitometric method which can be employed in the routine analysis of miconazole in creams has been developed and validated as per the International Conference on Harmonization (ICH) guidelines and the United States Pharmacopeia (USP) guidance. The method involves the use of a mobile phase composed of safer reagents for both the user and the environment than the previously available methods. In this method, ethyl acetate—ammonia solution 25% (25:0.5 v/v) was an optimum composition of a solvent system on precoated HPTLC silica gel 60 F254 glass plates with a saturation time of 25 min and migration rate of 10.5 min per 70 mm migration distance. The R f value was 0.57 with no interferences from excipients or solvents at the detection wavelength of 228 nm. The relative standard deviation (RSD) values of 1.14 and 1.98 were obtained for repeatability and intermediate precision, respectively, of the method. The polynomial R 2 values computed on three successive days for linearity testing were 0.984, 9.81, and 0.992. Accuracy values between 97.95% and 106.86% were obtained when testing was performed at 80%, 100%, and 120% concentration levels. The method is of acceptable selectivity and reproducibility as well as of easy use.

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Centella asiatica (L.) Urban, Apiaceae, is a medicinal plant, rooted in the Ayurvedic medicine with wide and potent health beneficial activity, and is of great interest to researchers concerning phytotherapy due to its numerous pharmacological activities. In this paper, we have developed a valid thin-layer chromatography (TLC)–densitometric method for the simultaneous determination of the four main C. asiatica active compounds. The additional goal was to achieve the conditions of determination, which would not require spraying with the derivative reagent and subsequent heating ? the factors that greatly deteriorate the validation parameters. In order to do so, we have tested diff erent sorbents (alumina, silica gel, and high-performance thin-layer chromatography [HPTLC] silica gel) and a number of eluents. The best results were obtained with HPTLC silica gel plates eluted with a mixture of CHCl3–MeOH–H2O (10:8:2, v/v) and analysed with a densitometer at λ = 202 nm. The chromatographic method was validated for linearity, limit of detection, limit of quantification, repeatability, intermediate precision, and recovery.

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Abstract  

121Sb Mössbauer spectra of the title complexes, whose isomer shifts are intermediate between the organoantimony(III) and organoantimony(V) compounds, suggest that considerable electrons are donated from hydrido ligand and Fe(CO)4 fragments to the antimony atom.

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form various intermediates. In air, most of the complexes give metal oxide as the final residue [ 3 ]. However, in inert atmosphere, metal is obtained as the final product [ 2 ]. In this study, we have investigated in detail the thermal decomposition

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.48–249.18 °C, in first step corresponded to the formation of VO(acac) as the probable intermediate. The mass loss of 17.23% in second step suggested the formation of VO 2 as the ultimate decompositional product. The DTA curve of complex (III) showed a single

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