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
Email: schalk@unf.edu
Website: @unf

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Polyphenols

  • IUPAC Name: [(2R,3R)-5,7-dihydroxy-2-(3,4,5-trihydroxyphenyl)-3,4-dihydro-2H-chromen-3-yl] 3,4,5-trihydroxybenzoate
  • Molecular Formula: C22H18O11
  • CAS Registry Number: 989-51-5
  • InChI: InChI=1S/C22H18O11/c23-10-5-12(24)11-7-18(33-22(31)9-3-15(27)20(30)16(28)4-9)21(32-17(11)6-10)8-1-13(25)19(29)14(26)2-8/h1-6,18,21,23-30H,7H2/t18-,21-/m1/s1
  • InChI Key: WMBWREPUVVBILR-WIYYLYMNSA-N

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Citations 6

"Online Coupling Of A Liquid-liquid Extraction Flow-reversal System To A Spectrophotometric Flow-through Sensor For The Determination Of Polyphenols In Olive Oil"
Anal. Chim. Acta 1996 Volume 323, Issue 1-3 Pages 55-62
M. P. Cañizares, M. T. Tena and M. D. Luque De Castro*

Abstract: The sensor for the spectrophotometric determination of polyphenols at 750 nm consisted of a flow-through cell (18 µL volume, 1.5 mm optical pathlength) packed with DEAE-Sephadex anion exchanger (40-120 µm) impregnated with Folin-Ciocalteu reagent. The sensor was incorporated into a flow injection manifold for the liquid-liquid extraction of polyphenols from diluted olive oil. A 500 µL sample of diluted olive oil (1:5 with hexane) was injected into 0.1 M NaHCO3 and propelled (1.3 ml/min) through an extraction coil (100 cm x 0.7 mm i.d.) several times by flow reversal. Only the analyte-enriched aqueous phase reached the sensor, where the analyte was retained and detected. The calibration graph, prepared with use of caffeic acid and 10^-20 flow-reversal cycles, showed linear segments for 15-30 µg/ml and 35-90 µg/ml, and the detection limit was 10 µg/ml. The sensitivity of the method improved with the number of cycles (N), while the RSD decreased. The sampling frequency was 11 per h for N = 10 and 8 per h for N = 20. The method was applied to the analysis of eight different olive oils, and the results are compared with those obtained by a conventional method based on the same chemical reaction.
Oil Ion exchange Spectrophotometry Sample preparation Sensor Method comparison Flow reversal Solvent extraction

"Determination Of Trans-resveratrol And Other Polyphenols In Wines By A Continuous-flow Sample Clean-up System Followed By A Capillary Electrophoresis Separation"
Anal. Chim. Acta 1998 Volume 359, Issue 1-2 Pages 27-38
Lourdes Arce, María Teresa Tena, Angel Rios and Miguel Valcárcel*

Abstract: A new method coupling flow injection (FI) with capillary electrophoresis (CE) was developed using diode array detection to measure the concentration. of trans-resveratrol in wines, in particular because of the interest in its biological properties and cancer prevention. A FI system furnished with a C-18 mini-column was used to clean up the wines by solid phase extraction prior to CE. The analytes were eluted from C-18 by using methanol and then driven from the FI system to the auto-sampler of the CE equipment by a programmable arm. The 3s detection limit ranged from 0.05 mg/L (trans-resveratrol) to 0.36 mg/L [(-)epicatechin]. The recoveries of added trans-resveratrol and other polyphenols from synthetic wines were between 92 to 110%, (mean of 99%). The method is faster and simpler than those previously reported which used liq.-liq. extraction and liquid chromatography
Wine Electrophoresis Spectrophotometry C18 Solid phase extraction

"Spectrophotometric Determination Of Tannin In Tanning Effluent With A Flow Injection System"
Analyst 1995 Volume 120, Issue 4 Pages 1185-1188
Valderi L. Dressler, Enio L. Machado and Ayrton F. Martins

Abstract: A 50 mL portion of tanning effluent was acidified with 5% HCl to pH 2, heated to boiling and allowed to cool. The pH of the solution was adjusted to 11 with 5% NaOH and the solution was re-boiled for 5 min, allowed to cool and filtered. The filtrate was adjusted to pH 6 with 5% HCl and diluted to 100 mL with water. A 200 µL portion of the resulting solution was injected into an aqueous carrier stream (6 ml/min) and merged with a stream (2 ml/min) of 2% NaOH and then with a stream (1 ml/min) of Folin-Ciocalteu reagent of pH 4-5 (1:4). The mixture passed through a 150 cm reaction coil and the absorbance was then measured at 670 nm. A diagram of the manifold used is given. The calibration graph was linear from 5-100 mg/l of tannin; the detection limit was 1.04 mg/l. The RSD (n = 10) was 2.9%. The throughput was 250 samples/h.
Process liquor Spectrophotometry pH

"Characterization Of Apple Cider Cultivars By Chemometric Techniques Using Data From High-performance Liquid Chromatography And Flow Injection Analysis"
Analyst 1998 Volume 123, Issue 6 Pages 1187-1191
D. Blanco-Gomis, I. Herrero-Sánchez and J. J. Mangas Alonso

Abstract: Anal. techniques (HPLC and flow injection anal.) for determining sugars, organic acids, polyphenols and pectins in apples, were employed along with chemometrics in the ripening and classification studies of cider apples. The use of principal component anal. allowed the authors to reduce the dimensionality of the data matrix; three new variables were obtained that accounted for 76% of variance. The projection of the apple cultivars in the reduced space allowed us to visualize the data structure on the basis of the degree of ripening and technol. characteristics of the cider apple varieties monitored. Linear discriminant anal. computed a canonical variable with a prediction capacity of 93%, using three groups for cancellation in order to validate the method. The use of modeling techniques, such as SIMCA and partial least squares made an adequate grouping of apple cultivars feasible on the basis of their degree of ripening.
Fruit HPLC Chemometrics

"Coupled Robot-flow Injection Analysis System For Fully Automated Determination Of Total Polyphenols In Olive Oil"
Anal. Chem. 1993 Volume 65, Issue 23 Pages 3540-3542
Jose A. Garcia-Mesa, M. Dolores Luque de Castro, and Miguel Valcarcel

Abstract: Details are given of a robotic system, based on a Zymate II Plus robot and a System V controller, by which (i) standard solution of 2-(4-hydroxyphenyl)ethanol were prepared from a 500 µg/l stock solution and placed in a FIA system for calibration, (ii) the oil sample was weighed, diluted with hexane and twice extracted with aqueous 60% methanol, and (iii) the aqueous methanol extract was introduced into the FIA system for dispersion in Folin-Ciocalteu reagent and subsequent merging with aqueous Na2CO3 before photometric detection at 725 nm. The adaptation of the manual extraction-photometric method and its optimization are fully described. Analysis time for the robotic method was 30 min, compared with 120 min for the manual method and 3.3 min for a FIA method described earlier (Anal. Chim. Acta, 1990, 235, 441); the calibration graph was linear for 50-700 µg/g of polyphenols in each instance. The robotic method showed the best precision with a RSD (n = 11) of 1.6% at 463 µg/g. Correlation between the manual and the robotic method was good (r2 = 0.9959). The development of an online robotic/flow injection analysis (FIA) method for the fully automated determination of total polyphenols in virgin olive oil is discussed. This coupled system allows more efficient use of robotic stations, which can concentrate on tasks that are too difficult for other automatic alternatives to perform, while the FIA instrumentation deals with the simpler operations. .
Oil Spectrophotometry Sample preparation Robot Extraction Optimization

"Determination Of Anti-carcinogenic Polyphenols Present In Green Tea Using Capillary Electrophoresis Coupled To A Flow Injection System"
J. Chromatogr. A 1998 Volume 827, Issue 1 Pages 113-120
Lourdes Arce, Angel Ríos and Miguel Valcárcel*

Abstract: A capillary electrophoresis (CE) method was developed for the simultaneous determination of a number of major ingredients of green tea. The components analyzed were caffeine, adenine, theophylline, epigallocatechin 3-gallate, epigallocatechin, epicatechin 3-gallate, (-)-epicatechin, (+)-catechin, gallic acid, quercetin and caffeic acid. Separation was achieved using a fused capillary column with 0.15 M H3BO3 as buffer at a pH of 8.5, UV detection at 210 nm and 20 kV of voltage. Analysis was carried out after treatment (extraction, filtration and dilution) of the samples in a flow injection system which was coupled to a CE equipment via a programmable arm. The procedure allows the determination of these compounds in <20 min. Quantitative analysis was performed by the standard addition method. Limits of detection ranged between 0.04 µg/mL for flavonols and 1.2 µg/mL for caffeine.
Leaves Electrophoresis Spectrophotometry Standard additions calibration