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TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS GRUPO 19 Cristina Ruiz Martínez Sara Ugarte Cerrato.

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Presentation on theme: "TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS GRUPO 19 Cristina Ruiz Martínez Sara Ugarte Cerrato."— Presentation transcript:

1 TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS GRUPO 19 Cristina Ruiz Martínez Sara Ugarte Cerrato

2 INDEX Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

3 Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

4 I NTRODUCTION quercetinmalvidin POLYPHENOL COMPOUNDS - Natural antioxidants widely distributed in the plant kingdom - Important determination - physiological effects - employment as markers in taxonomic studies - their properties to food quality control

5 Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

6 M ECHANISM CLASSICAL METHODS spectrophotometry gas chromatography liquid chromatography capillary electrophoresis Folin-Ciocalteau RECENT METHODS Biosensors: based on enzymes Advantages: rapid response cost-effectiveness simplicity of operation and manufacturing, minimal sample pretreatment and solvent requirements.

7 B IOSENSORS FOR POLYPHENOLS DETERMINATION

8 Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

9 SAMPLES RED WINE Enzyme: laccase Product of its oxidation: 1,2- benzoquinone reduced at the electrode. Actual mechanism of reaction still unclear. From spectroscopic and electron paramagnetic resonance (EPR) studies: 1º enzyme completely reduced 2º oxygen reduced to water

10 WINE SAMPLE Immobilization in polyethersulfone membranes: 1º Washings containing an excess of enzyme with acetate buffer. 2º A quantity deposited on polyethersulfone membrane cut in the form of discs. 3º Application to the electrode. 4º The biosensor is dipped in the buffer. 5º Injections of the sample or standard under magnetic stirring.

11 WINE SAMPLE Conclusion: able to discriminate between catechin and caffeic acid but negligible responses when using with wine. The complex matrix of the red wine samples interference in the response. More research to overcome the deviations.

12 Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

13 OLIVE OIL SAMPLE Two sensors: Biosensor based on the catalytic activity of the tyrosinase. Main advantages: -prior extraction pre-treatment analysis time not necessary eliminated decreased - Flow injection analysis - saving time - Semiautomization of - minimization of the entire procedure exposure to solvent vapors

14 OLIVE OIL SAMPLE Tyrosinase Pre-actived membrane Amperometric Gas Diffuse Electrode Gas permeable membrane Dialysis membrane Sensor Teflon O-ring

15 OLIVE OIL SAMPLE Voltammetric sensor Prior extraction Using a disposable screen-printed sensor (SPE) Reference compound: oleuropein A calibration curve of oleuropein

16 OLIVE OIL SAMPLE Electrode

17 Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

18 VEGETABLE EXTRACTS Enzyme: horseradish peroxidase. Inmmobilization: silica-titanium. Material with high chemical stability. Improvement of the amperometric detection. No significant influence of the matrix was observed.

19 VEGETABLE EXTRACTS Mechanism: double displacement or ping-pong.

20 Introduction Mechanisms Samples Red wine Olive oil Other vegetable extracts A new biosensor

21 N EW BIOSENSOR Based on laccase immobilized onto silver nanoparticles/multiwalled carbon nanotube/polyaniline gold electrode. Immobilization on AgNPs/PANI/MWCNT/Au (gold) electrode through covalent coupling to construct an enzyme electrode for determination of polyphenols. Employed for amperometric determination of total phenolic content in beverages and pharmaceutical formulation. Conclusion: good biosensor, likely to overcome the problem of leakage of enzyme.

22 THE END


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