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Chemical engineering is an engineering branch that deals with the chemical production and manufacture of products that undergo chemical processes. This includes equipment design, creating systems and processes to refine raw material, as well as mixing, compounding, and processing chemicals to create products.

Chemistry and Chemical Engineering

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A high performance thin layer chromatographic method has been developed for the determination of idebenone in pharmaceutical preparations. The method uses silica gel 60 F254 as the stationary phase, toluene–diethyl ether–methanol–triethylamine, 4 + 4 + 1.5 + 0.5 (v/v) as mobile phase, and detection at λ = 279 nm, the wavelength of maximum absorption of idebenone. Diclofenac sodium was used as internal standard. The response was found to be linearly dependent on amount of idebenone between 100 and 1000 ng mL–1. The method was validated to determine its accuracy and precision and the repeatability of the method was also determined. System suitability tests were conducted to verify that the resolution and reproducibility of the chromatographic system are adequate for the analysis. The determination of idebenone in tablets is described.

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A quantitative instrumental high-performance thin-layer chromatographic (HPTLC) method has been developed for assessment of the photodegradation of bensulfuron-methyl on silica gel. The method uses automated band application on to silica gel plates with fluorescent indicator, direct development after irradiation, and scanning densitometry of fluorescence-quenched zones of samples and standards. The accuracy of the analyses was confirmed by performing recovery studies with preanalyzed samples and a blank sample fortified with the analytes. Precision was determined by analyzing samples in replicate; loaded amounts of 500–2000 ng per spot were suggested for assessing the photodegradation of the pesticides. The simplicity of sample preparation and the chromatographic techniques, high sample throughput, high reproducibility, and the strong possibility of separating the photoproducts seem to make the test on HPTLC plates highly suitable for estimation of the photodegradability of pesticides in the adsorbed state.

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Homologous series of higher fatty acids, higher alcohols, and methyl esters of higher fatty acids have been separated by RPTLC. The values of R M and of the log P Rek partition coefficient from Rekker for the compounds of the homologous series could be correlated with numerical values of topological indexes based on the adjacency matrix (M, °χ, 1χ, °χν, 1χν ), and on the distance matrix (W, A, °B,1B). The most accurate prediction of the R M and log P Rek values of the compounds investigated was achieved by use of monoparametric equations containing one topological index based on the adjacency matrix.

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Two-dimensional thin layer chromatography of twelve flavonoids and three phenolic acids from Betula sp. leaves has been performed in normal-phase systems. Plots showing the dependence of RM on modifier concentration in some non-aqueous systems were used to optimize the chromatographic separation. RM values were correlated for all the chromatographic systems investigated and optimum pairs of systems were then selected for use in two-dimensional TLC separations. Complete separation of the compounds investigated was achieved by use of two optimum non-aqueous mobile phases on silica plates.

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The normal-phase (NP) and reversed-phase (RP) thin-layer chromatographic separations of aminoglycosides (streptomycin, kanamycin, gentamycin, and tobramycin) have been investigated on silica gel and C18 plates, respectively. The mobile phase acetone–2% sodium acetate–acetic acid–butanol, 7 + 6 + 4 + 1 (v/v) was successful for NPTLC and acetonitrile–5 mM sodium acetate buffer (pH 4.6) 4 + 18 (v/v) for RPTLC. The spots were located by use of iodine vapor. The minimum detection limits were in the range 0.4–0.6 μg. The method is a simple and direct approach for detection which does not require pre- or post-chromatographic derivatization.

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Complexes of hydroxy- and alkyloxytetraphenylporphyrins with Cu (II), Zn (II), and Ni (II) have been prepared and their chromatographic behavior in adsorption and partition thin-layer chromatography has been investigated. Gutman topological indexes, Mν, and the screening effect, SE, of the hydrocarbon chains on the electron pairs of the oxygen atoms of –OR groups have been calculated for the metalloporphyrin derivatives studied. The correlation between these and chromatographic retention, expressed as RM values, has been studied.

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