Isocratic elution system for the determination of catechins, caffeine and gallic acid in green tea using HPLC

Wang, Huafu; Helliwell, Keith; Xiaoqing, You

doi:10.1016/s0308-8146(99)00179-x

Cited by 206 publications

(124 citation statements)

References 13 publications

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“…' The aim of this work was to develop and validate an analytical method for quantitative determination of seven flavan-3-ols, present in a wide range of concentrations, suitable for a routine quality control (QC) of fermented tea infusions and ready-to-drink teas. The most representative flavan-3-ols, selected in agreement with the literature data [3,5,[15][16][17][18][19][20][21][22][23], were (À)-EGC, (1)-C, (À)-EGCG, (À)-EC, (À)-GCG, (À)-ECG, and (À)-CG. HPLC-UV/DAD was chosen to quantify the above markers with a certain level of confidence (accuracy and precision) because of its suitability for routine analyses (i.e.…”

Section: Introductionmentioning

confidence: 54%

“…In particular, method performance parameters, evaluated on the basis of a rigorous validation protocol, revealed lower LODs and LOQs when compared with previous methods [3,34], a better resolution between analytes [16,17,19,[20][21][22] shorter analysis times [16,18], thus minimizing the analysis cost. Furthermore, it also demonstrated good selectivity and accuracy, making it possible to quantify flavan-3-ols without any sample pretreatment and in spite of the complexity of the polyphenolic fraction and the possible presence of other interfering ingredients.…”

Section: Resultsmentioning

confidence: 93%

“…Several studies [12,13] demonstrated that tea catechins can scavenge reactive oxygen species (ROS), thanks to the phenolic hydroxyl group present in the flavan-3-ol structure, and also prevent their formation by inhibiting the xanthine oxidase [14]. The beneficial effects on human health have constantly increased the consumers' interest in the quality of tea beverages and stimulated several studies dealing with the characterization of their polyphenol profile [3,5,[15][16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Identification, quantitation, and method validation for flavan‐3‐ols in fermented ready‐to‐drink teas from the Italian market using HPLC‐UV/DAD and LC‐MS/MS

Cordero

Canale

Rio

et al. 2009

J of Separation Science

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The present study is focused on flavan-3-ols characterizing the antioxidant properties of fermented tea (Camellia sinensis). These bioactive compounds, object of nutritional claims in commercial products, should be quantified with rigorous analytical procedures whose accuracy and precision have been stated with a certain level of confidence. An HPLC-UV/ DAD method, able to detect and quantify flavan-3-ols in infusions and ready-to-drink teas, has been developed for routine analysis and validated by characterizing several performance parameters. The accuracy assessment has been run through a series of LC-MS/MS analyses. Epigallocatechin, (1)-catechin, (À)-epigallocatechingallate, (À)-epicatechin, (À)-gallocatechingallate, (À)-epicatechingallate, and (À)-catechingallate were chosen as markers of the polyphenolic fraction. Quantitative results showed that samples obtained from tea leaves infusion were richer in polyphenolic antioxidants than those obtained through other industrial processes. The influence of shelf-life and packaging material on the flavan-3-ols content was also considered; markers decreased, with an exponential trend, as a function of time within the shelf life while packaging materials demonstrated to influence differently the flavan-3-ol fraction composition over time. The method presented here provides quantitative results with a certain level of confidence and is suitable for a routine quality control of iced teas whose antioxidant properties are object of nutritional claim.

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Section: Introductionmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Identification, quantitation, and method validation for flavan‐3‐ols in fermented ready‐to‐drink teas from the Italian market using HPLC‐UV/DAD and LC‐MS/MS

Cordero

Canale

Rio

et al. 2009

J of Separation Science

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“…Analytical techniques, such as gas chromatography, spectrophotometry, nuclear magnetic resonance spectroscopy and biosensors have also been used for the determination of catechin. [1][2][3][4][5][6][7][8][9] The development of functional models of metalloenzymes for catalyst oxidation reactions is a subject of great interest. [10][11][12][13][14][15][16] Neves et al [17][18][19][20][21][22][23][24][25] have extensively synthesized and characterized model complexes to mimic the active site of the different enzymes (e.g., catechol oxidase, peroxidase, galactose oxidase, catalase, purple acid phosphatase).…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9] High-performance liquid chromatography and capillary electrophoresis with ultraviolet detection are the most cited techniques for separation, identification and quantitation. However, mass spectrometry, and electrochemical, fluorescence and chemiluminescence detection are also used in cases where more sensitive or selective detection is needed.…”

Section: Introductionmentioning

confidence: 99%

Determination of catechin in green tea using a catechol oxidase biomimetic sensor

Fernandes

Osório

Anjos

et al. 2008

J. Braz. Chem. Soc.

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Um sensor biomimético catecol oxidase, baseado em um novo complexo cobre(II) foi desenvolvido para determinação de catequina em chá verde e os resultados comparados com os obtidos por eletroforese capilar. O complexo dinuclear de cobre(II) [Cu 2 (HL)(µ-CH 3 COO)] (ClO 4 ), contendo o ligante N,N-[bis-(2-piridilmetil)]-N',N'-[(2-hidroxibenzil)(2-hidroxi-3,5-di-tert-butilbenzil)]-1,3-propanodiamino-2-ol (H 3 L), foi sintetizado e caracterizado por IV, 1 H RMN e análise elementar. As melhores condições para otimização do sensor biomimético foram estabelecidas por voltametria de onda quadrada. O melhor desempenho desse sensor foi obtido em 75:15:10% (m/m/m) de pó de grafite:nujol:complexo de cobre(II), tampão fosfato 0,05 mol L -1 (pH 7,5) e freqüência, amplitude de potencial, incremento em 30 Hz, 80 mV, 3,3 mV, respectivamente. A curva analítica foi linear na faixa de concentração 4,95 × 10 -6 a 3,27 × 10 -5 mol L -1 (r=0,9993) com limite de detecção de 2,8 × 10 -7 mol L -1 . Esse sensor biomimético demonstrou longo tempo de estabilidade (9 meses; 800 determinações) e reprodutibilidade com um desvio padrão relativo de 3,5%. A recuperação da catequina em amostras de chá verde variou de 93,8 a 106,9% e a determinação, comparada com a obtida usando eletroforese capilar, mostrou-se aceitável a um nível de confiança de 95%.A catechol oxidase biomimetic sensor, based on a novel copper(II) complex, was developed for the determination of catechin in green tea and the results were compared with those obtained by capillary electrophoresis. The dinuclear copper(II) complex, [Cu 2 (HL)(µ-CH 3 COO)](ClO 4 ), containing the ligand N,N-[bis-(2-pyridylmethyl)]-N',N'-[(2-hydroxybenzyl)(2-hydroxy-3,5-ditert-butylbenzyl)]-1,3-propanediamine-2-ol (H 3 L), was synthesized and characterized by IR, 1 H NMR and elemental analysis. The best conditions for the optimization of the biomimetic sensor were established by square wave voltammetry. The best performance for this sensor was obtained in 75:15:10% (m/m/m) of the graphite powder:nujol:copper(II) complex, 0.05 mol L -1 phosphate buffer solution (pH 7.5) and frequency, pulse amplitude, scan increment at 30 Hz, 80 mV, 3.3 mV, respectively. The analytical curve was linear in the concentration range 4.95 × 10 -6 to 3.27 × 10 -5 mol L -1 (r = 0.9993) with a detection limit of 2.8 × 10 -7 mol L -1 . This biomimetic sensor demonstrated long-term stability (9 months; 800 determinations) and reproducibility with a relative standard deviation of 3.5%. The recovery of catechin from green tea samples ranged from 93.8 to 106.9% and the determination, compared with that obtained using capillary electrophoresis, was found to be acceptable at the 95% confidence level.Keywords: catechin, green tea, biomimetic sensor, square wave voltammetry IntroductionTea is one of the most consumed beverages in the world and was firstly used in China for its medicinal properties 5000 years ago. Recent epidemiological studies have shown that the consumption of tea may help to prevent cancers in humans because the tea l...

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Extraction and Isolation of Polyphenolics

Kim

Lee

2002

Current Protocols in Food Analytical Chemistry

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Polyphenolics constitute a wide range of chemical compounds composed of aromatic ring(s) with one or more hydroxyl substituents, including their functional derivatives. Methods for extraction and isolation of polyphenolics from plant material are described in this unit. Extraction and isolation are the first important steps for separation, characterization, and quantification of polyphenolics from plant material. Polyphenolics are often most soluble in organic solvents less polar than water. The solubility is dependent on the polar properties of the polyphenolics. The correct selection of the extracting solvent is not as simple as it may seem. Aqueous methanol is a popular choice of solvent (see Background Information). Basic Protocol 1 describes the extraction of polyphenolics from freeze-dried powdered plant material using aqueous methanol and an ultrasound bath. The cavitation produced by ultrasound when used in aqueous methanol extraction assists to increase the mass transfer rate and allows higher product yield with reduced extraction time and solvent usage. Alternate Protocol 1 describes a simple sample preparation for the extraction of polyphenolics from fresh raw plant material using methanol and homogenization. Basic Protocol 2 describes an effective solid-phase extraction for isolation/purification of polyphenolics into non-anthocyanin and anthocyanin fractions. Interfering compounds such as sugars and organic acids are eliminated in this procedure. Alternate Protocol 2 describes the fractionation of polyphenolics into neutral and acidic fractions based on the fact that polyphenolic acids are completely ionized at pH 7.0 and un-ionized at pH 2.0. BASIC PROTOCOL 1 ULTRASOUND-ASSISTED AQUEOUS METHANOL EXTRACTION OF POLYPHENOLICS In this method, 80% aqueous methanol and ultrasound are used to extract polyphenolics from freeze-dried powdered plant material. Ultrasound-assisted extraction is a rapid and efficient method for the extraction of polyphenolics. Low-frequency, high-energy, highpower ultrasound in the kHz range has the advantage of significantly reducing extraction time and enhancing extraction yield. The use of fine powdered plant material maximizes polyphenolics extraction by increasing the surface area of the sample and facilitating the disruption of biological cell walls. Materials Freeze-dried powdered plant material, ground with a blender (e.g., Waring) or laboratory mill (e.g., Thomas-Wiley) and stored at −18°C under nitrogen gas, protected from light 80% (v/v) aqueous methanol Nitrogen gas Absolute methanol 500-ml Erlenmeyer flask Ultrasonic cleaning bath Whatman no. 2 filter paper Buchner funnel 1000-ml round-bottom evaporating flask Rotary evaporator with water aspirator or vacuum pump, 40°C water bath CAUTION: Sonication, filtration, and transfer should be performed in a fume hood. Personal protection equipment-laboratory coat, gloves, and safety glasses-must be used. Ear protection should be utilized during sonication.

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Isocratic elution system for the determination of catechins, caffeine and gallic acid in green tea using HPLC

Cited by 206 publications

References 13 publications

Identification, quantitation, and method validation for flavan‐3‐ols in fermented ready‐to‐drink teas from the Italian market using HPLC‐UV/DAD and LC‐MS/MS

Identification, quantitation, and method validation for flavan‐3‐ols in fermented ready‐to‐drink teas from the Italian market using HPLC‐UV/DAD and LC‐MS/MS

Determination of catechin in green tea using a catechol oxidase biomimetic sensor

Extraction and Isolation of Polyphenolics

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