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: Food -> butter

Citations 10

"Determination Of The Substrates Of Dehydrogenases In Biological Material In Flow Injection Systems With Electrocatalytic NADH Oxidation"
Anal. Chim. Acta 1984 Volume 163, Issue 1 Pages 299-303
A. Schelter-Graf, H. -L. Schmidt and H. Huck

Abstract: Applications are described of the NADH-sensitive system described previously (Huck et al., Anal. Abstr., 1984, 46, 8J126) that incorporated epoxyacrylic resin-bound dehydrogenases and a modified graphite electrode. The determination of D- and L-lactate in butter, L-glutamate in beef cubes, and ethanol in beer, and the control of the enzymatic hydrolysis of N-acetyl-DL-leucine by aminoacylase are discussed. The results obtained agreed well with those by spectrophotometric methods.
Ethanol l-Glutamate d-Lactate l-Lactate N-Acetyl-DL-leucine Electrode Potentiometry Method comparison Reactor Enzyme

"Determination Of Cholesterol By Flow Injection Analysis With Immobilized Cholesterol Oxidase"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 293-297
M. Masoom and Alan Townshend

Abstract: The injected sample passes at pH 7 through a column of cholesterol oxidase, immobilized on controlled-porosity glass by cross-linking with glutaraldehyde, and the H2O2 produced is detected with an amperometric flow-cell detector. The calibration graph of peak height vs. concentration. is rectilinear for up to 80 mg dl-1 with a coefficient of variation of 1 to 3%, the detection limit is 0.2 µg, and the achievable sample throughput is 80 h-1. The method was applied to the determination of cholesterol in blood serum, wax-wool alcohol and a butter extract and gave results in good agreement with those obtained by established procedures.
Cholesterol Amperometry Controlled pore glass Immobilized enzyme Method comparison

"Automatic Determination Of Liposoluble Vitamins In Butter And Margarine Using Triton X-100 Aqueous Micellar Solution By Liquid Chromatography With Electrochemical Detection"
Anal. Chim. Acta 1995 Volume 315, Issue 1-2 Pages 201-208
M. M. Delgado-Zamarreño*, A. Sanchez-Perez, M. C. Gomez-Perez and J. Hernandez-Mendez

Abstract: An automated flow system for the determination of vitamins A, D3 and E in butter and margarine was constructed by coupling a sample treatment system (alkaline hydrolysis and SPE) with LC. A sample stream containing 2 g of butter or margarine in 25 mL of 3% Triton X-100 was merged with an alcoholic NaOH reagent stream (reagent details given) and the mixture was passed through a reactor coil (RC; 5 m x 0.05 mm i.d.). The flow from the RC was merged with 2.2 M acetic acid and passed through the Sep-Pak plus C18 SPE cartridge at 1 ml/min for 6 min. The cartridge was washed with water/methanol (3:2) for 4.5 min and then the retained analytes were eluted (1 ml/min) with methanol through a 100 µL injection loop. After 4 min the contents of the loop was injected into the LC system. The chromatography was performed on a 5 µm OD-224 RP18 column (22 cm x 4.6 mm i.d.) with a 7 µm RP18 pre-column (1.5 cm x 3.2 mm i.d.) with 2.5 mM acetic acid/sodium acetate in methanol/water (99:1) as the mobile phase (1 ml/min) and electrochemical detection at at 1.3 V vs. Ag/AgCl. Linear calibration graphs were obtained and the detection limits were 0.035, 1.8 and 0.31 µM for vitamins A, D3 and E, respectively. The day-to-day RSD (n = 10) of the method was 2.4-5.8%. Results were in agreement with those obtained by classical methods.
Vitamin A Vitamin D3 Vitamin E HPLC Electrochemical analysis Sample preparation C18 Extraction Triton X Surfactant Micelle

"Determination Of Free Fatty Acids In Dairy Products By Direct Coupling Of A Continuous Preconcentration Ion-exchange-derivatization Module To A Gas Chromatograph"
Anal. Chem. 1994 Volume 66, Issue 5 Pages 628-634
Evaristo Ballesteros, Soledad Cardenas, Mercedes Gallego, and Miguel Valcarcel

Abstract: A flow injection ion-exchange system coupled to a gas-liquid chromatograph was used for the determination of free fatty acids in dairy products. The pretreatment module permits isolation and pre-concentration of free fatty acids on Amberlite IRA-400 and derivatization of eluted acids with acetyl chloride in methanol. The methyl esters are continuously injected via the injection port to prevent losses of the more volatile esters; they are quantified at the milligram per liter level with a FID detector. The method thus developed was applied to the determination of free fatty acids in milk, cream, and butter samples; fatty acids were also added to some samples to induce rancidity in order to assess the method performance. Copyright 1994, American Chemical Society.
Fatty acids, free Ion exchange GC Preconcentration Amberlite

"High Performance Liquid Chromatography And Post-column Derivatization With Diphenyl-1-pyrenylphosphine For Fluorimetric Determination Of Triacylglycerol Hydroperoxides"
J. Chromatogr. A 1992 Volume 596, Issue 2 Pages 197-202
Kazuaki Akasaka, Setsu Ijichi, Kenji Watanabe, Hiroshi Ohrui and Hiroshi Meguro*

Abstract: Butter, margarine and mayonnaise were diluted with water and extracted (x 2) with CHCl3 - methanol (2:1). The combined extracts were diluted with CHCl3 and subjected to HPLC on (a) a column (15 cm x 4.6 mm) of TSK-gel ODS 80Tm (5 µm) with a mobile phase (0.6 mL min-1) of methanol - 1-butanol (9:1) or (b) a column (15 cm x 4.6 mm) of Develosil Ph-5 phenyl column (5 µm) with a mobile phase (0.6 mL min-1) of methanol - water (19:1). In both instances, the eluent was mixed with a solution of 3 mg of diphenyl-1-pyrenylphosphine in 400 mL of methanol - acetone (3:1) pumped at 0.3 mL min-1 and the mixture was passed through a coil (20 m x 0.5 mm) at 80°C before fluorimetric detection at 380 nm (excitation at 352 nm). Calibration graphs were rectilinear for 2 to 1000 pmol of monohydroperoxides; there was no interference from dialkyl peroxides, unoxidized fatty acids, hydroxy acids or their esters. Column (a) was useful for separation of individual monohydroperoxides and column (b) was useful for their total determination as a class. The method was also be applied to the analysis of vegetable oils which were diluted with CHCl3 and subjected to HPLC as above.
Triacylglycerol hydroperoxide HPLC Fluorescence Post-column derivatization Interferences

"Highly Sensitive Flow Injection Analysis Of Lipid Hydroperoxides In Foodstuffs"
Biosci. Biotechnol. Biochem. 1996 Volume 60, Issue 11 Pages 1772-1775

Abstract: Edible oil, butter, margarine and mayonnaise samples were extracted with methanolic 50% butan-l-ol (details given). Portions (1-50 µL) of the extracts were injected into a carrier stream (0.8 ml/min) of methanolic 50% butan-l-ol, which merged a stream (0.3 ml/min) of 7.5 µg/ml diphenyl-l-pyrenylphosphine (reagent) in carrier solution containing 0.5 µg/ml 2,6-di-t-butyl-p-cresol, passed through a stainless-steel reaction coil (30 m x 0.5 mm i.d.) at 80°C then through a similar cooling coil (50 cm x 0.5 mm i.d.) prior to fluorimetric detection for lipid hydroperoxides at 380 nm (excitation at 352 nm). A second FIA system was also used which had a carrier stream flowing at 0.7 ml/min, a 30 µg/ml reagent stream flowing at 0.6 ml/min and a 50 m reaction coil. All other details were the same. For the first system the calibration graph was linear from 2-201 pmol trilinolein hydroperoxides (I), the detection limit was 2 pmol I and the RSD (n = 8) were 1.7-3.2%. For the second system, the calibration graph was linear from 0.4-79 pmol I, the detection limit was 0.2 pmol I and the RSD (n = 8) were 1.9-3.8%. Samples could be analyzed every 2 minutes, and results from both systems correlated well with those obtained by a batch method. Recoveries were 91.8-102%.
Lipids Hydroperoxide, lipid Trilinolein hydroperoxide Sample preparation Fluorescence Heated reaction Method comparison

"Determination Of Saponification Value Of Oils By FIA"
Bunseki Kagaku 1991 Volume 40, Issue 1 Pages 49-52
Katafuchi, A.;Imato, T.;Yagi, J.;Takahara, K.;Ishibashi, N.

Abstract: An ester solution (200 µL) was injected into an ethanol carrier stream (0.25 mL min-1) and merged with an ethanol stream containing 0.1 M tetrabutylammonium hydroxide (0.25 mL min-1). After mixing at 100°C in a 50-m reaction coil the stream was merged with 0.1 M butyric acid - ethanol containing 0.1 M LiCl and 0.2 µM-methyl red (0.5 mL min-1). The pH or absorbance of the mixed stream was measured at a glass electrode and/or at 490 nm. Calibration graphs were rectilinear from 0.02 to 0.1 M lauric acid ethyl ester; coefficient of variation was 1.3%. The sampling rate was ~20 samples h-1. The method was applied in the analysis of butter.
Fatty acids Electrode Heated reaction pH

"Colorimetric Assay For Free Fatty Acids In Butter Using Flow Injection And Immobilized Enzymes"
J. Food Sci. 1991 Volume 56, Issue 5 Pages 1229-1232
Schooner, F.;Simard, R.E.;Pandian, S.

Abstract: Butyrate kinase was extracted from frozen Escherichia coli DH5 pJc7 and purified by sonic oscillation in a buffer solution containing dithiothreitol, followed by centrifugation, hydrophobic interaction chromatography with an octyl-sepharose (4 cm x 2.5 cm) and a phenyl-sepharose (10 cm x 2.5 cm) column in series, dialysis, ultrafiltration, affinity chromatography on Matrex Red A (4 cm x 2.5 cm), chromatography on a phenyl-sepharose column (4.5 cm x 1.5 cm) and ultrafiltration. The enzyme was immobilized on porous glass beads and packed in a glass tube as a biosensor coupled with a flow injection analysis (FIA) system. Butter samples were analyzed by the batch method as described by Rose et al. (Methods in Enzymology, 1955, 1, 591) and by FIA coupled with the biosensor. Optical density was read at 510 nm. Detection limits were 25 ppm for the FIA system and 5 ppm for the batch method.
Fatty acids, free LC Spectrophotometry Sensor Sample preparation Buffer Extraction Filtration Immobilized enzyme Porous glass beads Dialysis

"Development Of FIA For Sensitive And Selective Determination Of Lactone Using A Chemiluminescent Reaction Between Acetone And Lactone In Carbon Dioxide Supercritical Fluid"
Nippon Kagaku Kaishi 1993 Volume 1993, Issue 7 Pages 845-849
Ishii, M.;Uchida, H.

Abstract: Lactone (I) was dissolved in acetone and the solution was injected into a stream of supercritical CO2 followed by chemiluminescence detection. The detection limit was 0.01 nM-I and the coefficient of variation (n = 5) was 2.3% for 0.1 µM-γ-butyrolactone. The method was highly selective to I and was applied in the analysis of butter.
Lactone Chemiluminescence Supercritical fluid

"D- And L-lactate Determination In Dairy Products: Presentation Of A Fast Automated Analysis System"
Z. Lebensm. Unters. Forsch. 1995 Volume 201, Issue 6 Pages 537-540
Thomas Becker, Hanns-Ludwig Schmidt and Erika Lechner

Abstract: A flow injection system is presented, which is versatile, automated and has an integrated enzyme system. Its efficiency at determining D- and L-lactate separately in dairy products is compared with the officially used reference method (DIN 10335). By means of a mathematical elimination of matrix effects, the pretreatment steps can be clearly reduced. As a result of the immobilization of the enzymes, an appropriate automation software and an adaptation of the system developed to the given medium, the analysis could be performed within 5 min and was distinctly cheaper than alternative methods. The values determined in 15 different dairy products deviated from those of the reference method by 3% at a maximum. (21 References)
d-Lactate l-Lactate Spectrophotometry Immobilized enzyme Standard method