Enzymic method for the spectrophotometric determination of aspartame in beverages

Hamano, Takashi; Mitsuhashi, Yukimasa; Aoki, Nobumi; Yamamoto, Susumu; Tsuji, Sumiko; Ito, Yoshio; Oji, Yoshikiyo

doi:10.1039/an9901500435

Cited by 15 publications

(6 citation statements)

References 7 publications

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“…At the flow typically used (40 mL min-') the cuvette was flushed approximately four times per min. Optimal conditions of the methanol oxidase/Fluoral-P reaction were checked and were identical with those described by Hamano et al (1990).…”

Section: Methanol Oxidase Methods For Methanol Quantitationmentioning

confidence: 99%

“…The assay of gas-phase methanol was based on a spectrophotometric determination of liquid-phase methanol (Klavons and Bennett, 1986;Hamano et al, 1990). Gas emerging from the leaf cuvette was bubbled via Teflon tubing through 2 mL of solution containing methanol oxidase (5 units, Pickia alcohol oxidase; Sigma), Fluoral-P (2 mg; Wako Pure Chemicals, Richmond, VA), and potassium phosphate buffer (0.2 M, pH 6.0).…”

Section: Methanol Oxidase Methods For Methanol Quantitationmentioning

confidence: 99%

“…We adapted an enzymatic procedure, originally developed to measure methanol in aqueous samples (Klavons and Bennett, 1986;Hamano et al, 1990), to the measurement of methanol in gases from leaf cuvettes. With this method, methanol partitions from the gas to liquid phase, where it is oxidized to formaldehyde by methanol oxidase, and the formaldehyde produced is continuously trapped by the reagent Fluoral-P to generate a stable, fluorescent product (Fig.…”

Section: Use Of Methanol Oxidase To Verify Methanol Emission From Leavesmentioning

confidence: 99%

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Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

et al. 1995

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We recently reported the detection of methanol emissions from leaves (R. MacDonald, R. Fall 119931 Atmos Environ 27A: 1709-171 3). This could represent a substantial flux of methanol to the atmosphere. Leaf methanol production and emission have not been investigated in detail, in part because of difficulties in sampling and analyzing methanol. In this study we used an enzymatic method to convert methanol to a fluorescent product and verified that leaves from severa1 species emit methanol. Methanol was emitted almost exclusively from the abaxial surfaces of hypostomatous leaves but from both surfaces of amphistomatous leaves, suggesting that methano1 exits leaves via stomates. The role of stomatal conductance was verified in experiments in which stomates were induced to close, resulting in reduced methanol. Free methanol was detected in bean leaf extracts, ranging from 26.8 pg g-' fresh weight in young leaves to 10.0 pg g-' fresh weight in older leaves. Methanol emission was related to leaf development, generally declining with increasing leaf age after leaf expansion; this is consistent with volatilization from a cellular pool that declines in older leaves. It is possible that leaf emission could be a major source of methanol found in the atmosphere of forests.

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Section: Methanol Oxidase Methods For Methanol Quantitationmentioning

confidence: 99%

Section: Methanol Oxidase Methods For Methanol Quantitationmentioning

confidence: 99%

Section: Use Of Methanol Oxidase To Verify Methanol Emission From Leavesmentioning

confidence: 99%

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Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

et al. 1995

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“…Aspartame can be cleaved by the enzymic action of achymotrypsin 13 to give methanol, a product that is detectable using alcohol oxidase. The overall reaction is as follows: An aspartame biosensor with long term stability based on the immobilization of a-chymotrypsin (bovine pancreas) and alcohol oxidase (Hansenula sp.)…”

Section: Resultsmentioning

confidence: 99%

Amperometric Bienzymic Sensor for Aspartame

Compagnone¹,

O’Sullivan²,

Guilbault³

1997

Analyst

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An amperometric enzyme electrode for the determination of aspartame was developed by covalent immobilization of alcohol oxidase and alpha-chymotrypsin. A platinum based hydrogen peroxide electrode was used as the detector. Excellent sensitivity was obtained using batch, flow-through and flow injection methods with detection limits of 2 x 10(-7), 4 x 10(-7) and 10(-6) mol l-1, respectively. Different strategies for eliminating interfering compounds, including the introduction of an additional alcohol oxidase-catalase membrane and signal subtraction using an alcohol electrode, were employed. A recovery study on seven food samples was carried out and the results were satisfactory.

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“…Among these sweeteners, aspartame ( N - l -α-aspartyl- l -phenylalanine 1-methyl ester) has dominated the U.S. market with the 1995 estimated consumption at 18.8 million lb. It is rapidly replacing saccharin and cyclamate in the market as they are suspected to cause cancer even though currently there is controversy over the long-term health effects of these sweeteners in humans. , The determination of aspartame can be done by many analytical procedures such as spectrophotometry, − capillary electrophoresis, , thin-layer chromatography, and gas chromatography . High-performance liquid chromatography (HPLC) − is the most commonly used method for the quantification of aspartame.…”

mentioning

confidence: 99%

Aspartame Optical Biosensor with Bienzyme-Immobilized Eggshell Membrane and Oxygen-Sensitive Optode Membrane

Xiao

Choi

2002

Anal. Chem.

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An aspartame optical biosensor has been fabricated by employing a bienzyme system composed of alpha-chymotrypsin and alcohol oxidase immobilized onto an eggshell membrane and an oxygen-sensitive optode membrane as the transducer. The detection schemes involve the enzymatic reactions of aspartame leading to the depletion of the oxygen level of the medium with a concomitant enhancement of the fluorescence intensity of the oxygen-sensitive membrane. The scanning electron and transmission electron micrographs show the microstructure of the eggshell membrane which is successfully immobilized with bienzyme. Using this novel immobilization technique, the aspartame biosensor shows extremely good stability with a shelf life of at least 8 months. The rate change of the fluorescence intensity in 4 min is found to be linearly related to the concentration of aspartame. The useful analytical working range of the biosensor is from 0.056 to 3.07 mM aspartame. The effects of temperature, pH, and ionic strength on the response of the aspartame biosensor are investigated in detail. Citric acid, cyclamic acid, D-fructose, D-galactose, D-glucose, hydrogen peroxide, DL-malic acid, L-phenylalanine, saccharin, sodium benzoate, and sucrose show no interferences but ethanol interferes strongly. The aspartame biosensor has been applied to determine aspartame contents in some commercial products.

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Enzymic method for the spectrophotometric determination of aspartame in beverages

Cited by 15 publications

References 7 publications

Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

Amperometric Bienzymic Sensor for Aspartame

Aspartame Optical Biosensor with Bienzyme-Immobilized Eggshell Membrane and Oxygen-Sensitive Optode Membrane

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