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Biphasic Sonoelectroanalysis: Simultaneous Extraction from, and Determination of Vanillin in Food Flavoring
Author(s) -
Hardcastle Joanna Lorraine,
Paterson Clare J.,
Compton Richard G.
Publication year - 2001
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200107)13:11<899::aid-elan899>3.0.co;2-e
Subject(s) - vanillin , detection limit , extraction (chemistry) , chemistry , ethyl acetate , chromatography , electrochemical gas sensor , square wave , voltammetry , solvent , ethyl acetoacetate , electrochemistry , aqueous solution , electrode , organic chemistry , physics , voltage , quantum mechanics , catalysis
Abstract Biphasic sonoelectroanalysis is employed in the detection of vanillin (4‐hydroxy‐3‐methoxybenzaldehyde). Ethyl acetoacetate is characterized as an electrochemical and sonoelectrochemical solvent and it is shown that quantitative electrochemical measurements can be made in this solvent of relatively low dielectric constant. The electrochemical oxidation of vanillin in this medium is shown to give oxidative linear sweep voltammetric signals sensitive to microadditions. In addition, the near reversible kinetics of vanillin in ethyl aceto‐acetate facilitate sensitive square‐wave voltammetry. Electrode passivation leads to typically diminishing peak heights for the same concentration of vanillin, but by employing ultrasound between each scan, peak heights are maintained by quantitative depassivation of the electrode surface. Microadditions of 0.05 mM vanillin to ethyl acetoacetate yield a linear calibration plot with r =0.9987 and a detection limit of 0.016 mM. The determination of vanillin in natural vanilla essence is then achieved by the exploitation of biphasic sonoelectrovoltammetry in aqueous ethanolic vanilla pod extract and ethyl acetoacetate. In contrast with silent voltammetry, ultrasound facilitates emulsification and extraction of vanillin in the extract permitting an analytical square‐wave voltammetric signal to be obtained. Microadditions to two separate samples of vanilla essence facilitate quantification of vanillin in the extract. Close agreement with a blind analysis of the samples using HPLC‐UV is observed with a limit of detection in the biphasic medium of 0.020 mM. Biphasic sonoelectroanalysis removes the need for sample degradation or a separation step, which would lengthen and complicate the analytical protocol. It can therefore be concluded that biphasic sonoelectroanalysis demonstrates an attractive alternative to currently accepted techniques.