Use of multivariate statistical techniques to optimize the simultaneous separation of 13 phenolic compounds from extra-virgin olive oil by capillary electrophoresis

Characterization of phenolic compounds in olive oil has not been achieved as yet, owing to the complexities of their chemical structures and analytical matrix. The aim of this work is to optimize and validate a method for simultaneous separation and quantification of 13 phenolic compounds from extra-virgin olive oil: tyrosol, hydroxytyrosol, oleuropein glycoside, ferrulic acid, p-coumaric acid, cinnamic acid, p-hydroxybenzoic acid, gallic acid, caffeic acid, luteolin, apigenin, vanillic acid and 3,4-dihydroxybenzoic acid. A statistical central composite design, response surface analysis and the simultaneous optimization method of Derringer and Suich were used to separate all the peaks. These multivariate procedures were efficient in determining the optimal separation condition, using five peak-pair resolutions and runtime as responses. The optimized method employed a fused-silica capillary of 50 μm i.d. × 60 cm effective length with extended light path, 50 mmol L⁻¹ boric acid electrolyte, 10.2 pH, 25 °C, injection of 50 mbar for 25 s with application of reverse voltage (−30 kV for 5 s) before setting the running voltage (+30 kV) with detection at 210 nm and a run time of 12 min. Peak resolutions are found to be very sensitive to pH values outside the 10.15-10.25 range but acceptable electropherograms can be obtained for a wide range of boric acid concentrations within this pH interval.     

Polar factorization of conformal and projective maps of the sphere in the sense of optimal mass transport

Let M be a compact Riemannian manifold and let μ, d be the associated measure and distance on M. Robert McCann, generalizing results for the Euclidean case by Yann Brenier, obtained the polar factorization of Borel maps S: M → M pushing forward μ to a measure ν: each S factors uniquely a.e. into the composition S = T ? U, where U: M → M is volume preserving and T: M → M is the optimal map transporting μ to ν with respect to the cost function d²/2.In this article we study the polar factorization of conformal and projective maps of the sphere S ⁿ . For conformal maps, which may be identified with elements of O_o(1, n+1), we prove that the polar factorization in the sense of optimal mass transport coincides with the algebraic polar factorization (Cartan decomposition) of this Lie group. For the projective case, where the group GL+(n + 1) is involved, we find necessary and sufficient conditions for these two factorizations to agree.     

Cytogenetics of four species of Spirostreptidae (Diplopoda, Spirostreptida)

Considering an estimated number of millipedes of approximately 80,000, cytogenetic studies on these animals are rare, as only a total of 70 species have their karyotypes described. The present study reports on the chromosomal number of four Brazilian diplopods of the family Spirostreptidae: Urostreptus atrobrunneus with 2n = 24, XY; Gymnostreptus olivaceus 2n = 12, XY and Alloporus araraquarensis and A. principes, 2n = 18, XY. The C-banding pattern and NOR staining of U. atrobrunneus, G. olivaceus and A. araraquarensis are described.     

Determination of hexacelsian by infrared spectroscopy

Hexacelsian has been determined by infrared spectroscopy with KBr discs and K(4)Fe(CN)(6) as internal standard. A KBr particle size of <40 mum gave better homogenization of the sample-KBr mixture than a particle size in the 40-70 mum range. For determinations of hexacelsian in synthetic samples containing amorphous phase or celsian, calibration curves were constructed. A least-squares fit yielded correlation coefficients of 0.998 and 0.997.     

Ru-Catalyzed Oxidation of Acetylenes to α-Diketones with Iodosylbenzene

Disubstituted acetylenes are oxidized with PhIO in presence of Ru-catalysts to afford α-diketones in 65–85% yield. Under the same conditions terminal acetylenes are cleaved to carboxylic acids.     

Synthesis and characterization of polymers derived from 2,5-dimethoxy-terephthaldehyde and 2,5-dimethoxy-terephthalic acid

Polyamides were synthesized from 2,5-dimethoxyterephthaloyl dichloride and diamines. Also, polyimines and polyaldoles were prepared from 2,5-dimethoxy-terephthaldehyde with diamines and ketones. The polymers were characterized by elemental analysis and infrared and NMR spectroscopy. Their intrinsic viscosity, glass transition temperature, and thermaldecomposition temperatures were determined.