University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Oil -> sunflower

Citations 2

"Membrane Extraction-preconcentration Cell Coupled Online To Flow Injection And Liquid Chromatographic Systems. Determination Of Triazines In Oil"
Anal. Chim. Acta 1995 Volume 304, Issue 3 Pages 323-332
R. Carabias Martínez*, E. Rodríguez Gonzalo, E. Hernández Fernández and J. Hernández Méndez

Abstract: The membrane extraction-pre-concentration (MEP) cell consisted of two channels separated by a Celgard 2500 membrane (0.025 mm thick, 45% porosity, 0.04 µm effective pore size). Oil samples diluted with hexane (1:4) were propelled through one channel and the acceptor solution was propelled through the other channel. The acceptor solution was held stationary during the extraction-pre-concentration period while the diluted oil sample was circulated continuously. The MEP cell was coupled online to FIA or HPLC systems for the determination of triazines in vegetable oils. The FIA system used 0.1 M HClO4 as the acceptor solution. At the end of the 5-15 min MEP period, the acceptor solution was propelled to the diode-array spectrophotometer where the total triazines were determined at 220 nm. The calibration graphs were linear (range not given) with detection limits of 0.91 ppm. RSD (n = 10) were 6%. The HPLC system used 5 mM HClO4 in methanol/H2O (9:1) as the acceptor solution. After MEP, the acceptor solution was analyzed on a 5 µm Spheri-5-RP 18 column (25 cm x 4.6 mm i.d.) with 50% aqueous acetonitrile as mobile phase (1.25 ml/min) and detection at 220 nm. Calibration graphs for the determination of atrazine, ametryne, prometryne and terbutryne in corn, sunflower and olive oil were linear for 0.05-20 ppm and the detection limits were ~e;0.1 ppm. RSD (n = 10) were 10%.
Herbicides Atrazine Ametryne Prometryne Terbutryne Spectrophotometry HPLC Sample preparation Celgard Membrane Preconcentration Extraction

"Spectrophotometric Determination Of Periodate With Salicylaldehyde Amidinohydrazone Using Flow Injection. Determination Of Glycerol In Vegetable Oils"
Analyst 1989 Volume 114, Issue 8 Pages 989-990
Juan José Berzas Nevado and Pablo Valiente González

Abstract: A 0.2 mL sample containing 50 ppm of IO4- was injected into a carrier stream of water (1 mL min-1) and then mixed with 0.06% salicylaldehyde amidinohydrazone solution followed by 0.25 M NH4Cl - NH3 buffer (pH 9.2) (both 1 mL min-1). The absorbance was measured at 490 nm; the calibration graph was rectilinear. Glycerol was determined by treatment with excess of IO4- and set aside for ~30 min before analysis as above. Oil was dissolved in CHCl3 before analysis. Recoveries from olive and sunflower oil were quantitative. The sampling rate was 20 h-1. Periodate has been determined using flow injection with spectrophotometric detection on the basis of the red color obtained when salicylaldehyde guanylhydrazone (SAG) and periodate were mixed in a basic medium. The carrier stream was de-mineralised water. The reagent stream was an aqueous SAG solution and another stream contained an ammonia buffer (pH 9.2) solution. The calibration graph was linear between 5 and 50 p.p.m. of periodate when the injection volume was 200 µL. The relative standard deviation (n= 10) was 1.0% and the detection limit, corresponding to a signal to noise ratio of 3, was 0.35 p.p.m. The proposed method was applied to the determination of glycerol in vegetable oils using the Malaprade reaction.
Periodate Glycerol Spectrophotometry Buffer