Determination of tert-butylhydroxyanisole and tert-butylhydroxytoluene by flow injection with amperometric detection

Yáñez‐Sedeño, P.; Pingarrón, José M.; Díez, L. M. Polo

doi:10.1016/0003-2670(91)87209-p

Cited by 36 publications

(10 citation statements)

References 15 publications

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“…Obviously, this was not made in the flow-injection mode and, consequently, fouling of the electrode surface due to the very strong adsorption processes of these antioxidants caused a continuous decrease in the flow-injection peaks. A similar behavior was also observed at a GC electrode under flowing conditions for BHT [15] and I-1076 [13]. As in these cases, a cleaning scheme of the electrode surface based on the pulse amperometric detection (PAD) methodology [16] can be developed to be applied after each injection.…”

Section: Flow-injection With Amperometric Detection Studiessupporting

confidence: 51%

Critical Comparison of Paraffin Carbon Paste and Graphite-Poly(tetrafluorethylene) Composite Electrodes Concerning the Electroanalytical Behavior of Various Antioxidants of Different Hydrophobicity

et al. 1998

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The voltammetric and flow-injection amperometric behaviors of several substances used as antioxidants in the food and pharmaceutical industries at carbon paste electrodes, with paraffin as binding agent, and at graphite-40 % PTFE composite electrodes were compared on the basis of the different hydrophobicity of the antioxidants. Aqueous solutions, alcohol-water mixtures and oil-in-water-emulsions were used as working media. No voltammetric or flow-injection responses were obtained for high hydrophobic antioxidants (BHT, Irganox-1076 and Irganox-1010) at graphite-PTFE electrodes. On the contrary, carbon paste electrodes allowed the attainment of analytically useful signals for these compounds. A pulse amperometric detection (PAD) scheme should be applied in these cases for the cleaning of the electrode surface. The use of graphite-PTFE electrodes seems to be advantageous for the less hydrophobic antioxidants such us propyl gallate and TBHQ. An adsorption process for PG and a faster electrode kinetic in the case of TBHQ were shown to occur by cyclic voltammetry at the PTFE composite electrode. Furthermore, this electrode allows the use of lower potentials for the amperometric detection of these compounds than the carbon paste electrode. Good reproducibility of the successive amperometric responses was also observed. The mutual influence of the electrode surface composition and the lipophilic characteristics of the molecules tested is discussed.

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Section: Flow-injection With Amperometric Detection Studiessupporting

confidence: 51%

Critical Comparison of Paraffin Carbon Paste and Graphite-Poly(tetrafluorethylene) Composite Electrodes Concerning the Electroanalytical Behavior of Various Antioxidants of Different Hydrophobicity

et al. 1998

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“…Some of these methods use techniques such as differential pulse, 19 square wave, 20,21 and cathodic stripping voltammetry. 22 Paraquat is a di-cation that can be easily accumulated on the surface of electrodes modified with cation exchanger materials, such as Amberlite XAD-2, 23 clays 24 and some surfactants.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a nafion coated glassy carbon electrode for determination of paraquat by differential pulse voltammetry

Oliveira¹,

Lichtig²,

Masini³

2004

J. Braz. Chem. Soc.

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Este trabalho apresenta uma avaliação de um eletrodo de carbono vítreo recoberto com filme de Nafion para a determinação de paraquat em águas de rio e urina por voltametria de pulso diferencial. O filme foi formado adicionando-se 4 µL de uma solução de Nafion 4% (m/v) na superfície do eletrodo, seguindo-se evaporação do solvente com luz infra-vermelha. A máxima relação sinal/ruído foi obtida em meio de tampão Britton-Robinson 40 mmol L -1 com pH 12 como eletrólito suporte. Utilizando-se um tempo de acumulação de 5 min em circuito aberto, o limite de detecção foi de 0,7 µg L -1 , enquanto o limite de quantificação foi de 1,0 µg L -1 , com uma faixa de resposta linear até 12 µg L -1 . Nestas condições, uma série de dez experimentos revelou um desvio padrão relativo de 2,2% para uma solução de paraquat 10 µg L -1 . A formação de par iônico em solução foi o principal fator de erro nas análises. Apesar do filme evitar a adsorção de espécies aniônicas na superfície do eletrodo, o paraquat sofre fortes associações em solução com substâncias húmicas, proteínas, argilas, surfactantes aniônicos, etc. Estas interações diminuem a acumulação do paraquat no filme de Nafion e, em conseqüência, diminuem a magnitude da corrente de pico de redução, requerendo que as quantificações sejam feitas por adição de padrão. Recuperações entre 87 e 106% foram obtidas para amostras de água de rio e urina enriquecidas aos níveis de 1,0 e 3,0 µg L -1 . This paper presents an evaluation of a Nafion coated glassy carbon electrode for determination of paraquat in river water and urine by differential pulse voltammetry. The film was formed applying 4 µL of a 1% (m/v) Nafion solution, which was evaporated under an infrared light. The maximum signal to noise ratio was obtained using a 40 mmol L -1 Britton-Robinson buffer at pH 12 as supporting electrolyte. For an accumulation time of 5.0 min in open circuit, the limit of detection was 0.7 µg L -1 , while the quantification limit was 1.0 µg L -1 , with a linear dynamic range up to 12 µg L -1 . In these conditions, a sequence of ten experiments lead to a relative standard deviation of peak current of 2.2% for a 10 µg L -1 paraquat solution. Ion pair formation in solution was the major factor of error in analysis. Despite the film to avoid adsorption of anionic species at the electrode surface, paraquat suffers strong association in solution with humic substances, proteins, clays, anionic surfactants, etc. These interactions decrease the accumulation of paraquat in the Nafion film and, as a consequence, the magnitude of the reduction peak, requiring that quantifications have to be made by standard addition. Recoveries between 87 and 106% were obtained for river waters and urine samples spiked with 1.0 and 3.0 µg L -1 paraquat.Keywords: paraquat determination, river water, urine, modified electrode, voltammetry, ion exchange IntroductionParaquat (1,1'-dimethyl-4,4'-bypiridilium ion), also known as methyl viologen, is a defoliant and desiccant agent used to control herbal growth in terrestrial and aquat...

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“…The linearity and LODs achieved (S/N = 3) are adequate for the usual analytical requirements for BHA and PG. 4 The reproducibility in terms of the peak heights of the method was also determined by running six replicates of the standard solution of antioxidants.…”

Section: Analytical Characterizationmentioning

confidence: 99%

Capillary Electrophoresis-Amperometric Determination of Antioxidant Propyl Gallate and Butylated Hydroxyanisole in Foods

Qian

Gao

et al. 2007

ANAL. SCI.

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Antioxidants, both synthetic and of natural origin, are widely applied to prevent the oxidative degradation of processed foods. Propyl gallate and butylated hydroxyanisole, as synthetic phenolic antioxidants, display high chemical activity for suppressing chain initiation, or breaking chain propagation of the peroxidation of unsaturated fatty acids. 1 Their molecular structures are shown in Fig. 1. Although they are powerful for protecting product quality in food distribution, excess antioxidants added to food might produce toxicities or mutagenicities, and thus harm the health of people. In most countries, the contents of phenolic antioxidants in processed food are strictly limited. Thus, the development of new analytical techniques for the fast determination of those antioxidants in food science has seen a huge recent increase as the result of an increased concern of consumers about food safety. 3 In general, the combination of two synthetic antioxidants is more effective than a single antioxidant used for food samples. Thus, difficulties have been encountered in the determination and separation of antioxidants due to a chemical similarity of the analytes, 4-6 which have resulted in mutual interference. Several detection methods without previous separation have been studied. With the aid of chemometrics approaches, the electroanalytical-voltammetric technique 1 and spectrophotometry 2 were employed to analyze antioxidants. Based on a joining of the stopped-flow mixing technique and a diode-array detector, photometric methodology was used for the simultaneous determination of BHA and PG. 7,8 Also, a continuous-flow injection means was described for the determination of two binary mixtures of the antioxidants in foods and cosmetics. Although many approaches for the analysis of PG and BHA reported above seem to be relatively simple, complicated calculations and a large volume sample requirement were the main problems concerning the detection process. Thus, the development of a faster, cleaner and simpler analytical procedure for the simultaneous determination of BHA and PG in food samples is very necessary in order to meet the demand Capillary electrophoretic separation coupled with end-column amperometric detection for the simultaneous quantification of butylated hydroxyanisole (BHA) and propyl gallate (PG) in food was developed. Important factors affecting separation and detection, such as the running buffer, separation voltage, and detection potential, were investigated in detail. An improved working electrode preparation method was used, where a carbon disk of 33 μm in diameter was sealed in a tip and positioned opposite the outlet of a capillary. The experiments indicated that the preparation method was simple, and the obtained electrode exhibited good flexibility and stability for the determination of phenolic antioxidants. The separation was carried out within 5 min using a 50 cm length capillary, with a solution containing 5 mM phosphate and 5 mM borax of pH 8.84 as a separation buffer, and a separation p...

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Determination of tert-butylhydroxyanisole and tert-butylhydroxytoluene by flow injection with amperometric detection

Cited by 36 publications

References 15 publications

Critical Comparison of Paraffin Carbon Paste and Graphite-Poly(tetrafluorethylene) Composite Electrodes Concerning the Electroanalytical Behavior of Various Antioxidants of Different Hydrophobicity

Critical Comparison of Paraffin Carbon Paste and Graphite-Poly(tetrafluorethylene) Composite Electrodes Concerning the Electroanalytical Behavior of Various Antioxidants of Different Hydrophobicity

Evaluation of a nafion coated glassy carbon electrode for determination of paraquat by differential pulse voltammetry

Capillary Electrophoresis-Amperometric Determination of Antioxidant Propyl Gallate and Butylated Hydroxyanisole in Foods

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