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Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
Propyl gallate (PG) is a significant synthetic antioxidant and preservative. Its determination has been studied at carbon paste electrode (CPE) using differential pulse voltammetry (DPV) and high performance liquid chromatography with electrochemical detection (HPLC-ED) and with UV spectrometric detection (HPLC-UV). Concentration dependences were measured in the media of Britton-Robinson buffer (pH 5) and methanol (20 %, v/v) by DPV and the limit of detection 0,6110-7 moldm-3 was obtained. Using HPLC with a mobile phase consisting of 0,01 moldm-3 phosphate buffer (pH 4) and methanol (50 %, v/v) with potential of working electrode E = +0,8 V and detection wavelength λ = 280 nm, concentration dependences were measured. Limit of detection was determined to 0,39 moldm-3 for HPLC-ED and 4,95 moldm-3 for HPLC-UV. After verification of the extraction procedure PG was determined in vegetable oil. The resulting value of 3,2 mgkg-1 corresponds with permited limits.
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Determination of synthetic antioxidants using HPLC with electrochemical detection on carbon felt detector
Baroch, Martin ; Dejmková, Hana (advisor) ; Fischer, Jan (referee)
Title: Determination of synthetic antioxidants using HPLC with electrochemical detection on carbon felt detector Author: Martin Baroch Supervisor: RNDr. Hana Dejmková, Ph.D. Department: Department of Analytical Chemistry The aim of this work was to find suitable conditions for HPLC separation with subsequent coulometric detection on a carbon felt detector. The analytes were synthetic phenolic antioxidants, specifically propyl gallate (PG), tert-Butylhydroquinone (tBHQ), butylated hydroxyanisole (BHA) and butylhydroxytoluene (BHT). For the complete separation of the analytes, gradient elution was required. As a mobile phase methanol and acetate-phosphate buffer of pH 4.5 were used. Concentration of methanol in mobile phase was linearly increased from 55 % to 95 % during 8 minutes and next 2 minutes was concentration of methanol held at 95 %. As a stationary phase was used Lichrospher® RP- 18 (125×4 mm, 5 µm) (LichroCART) column. Potentials putted on a carbon-fiber working electrode were 1.40 V for BHT and 0.80 V for other analytes. Two potentials were chosen for a better detector response to BHT. The calibration dependence of the signal on the concentration was observed in the concentration range of · 10-4 - 1 · 10-6 mol dm-3 for all analytes. In this range the dependencies are linear. Inaccurate...
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Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Fischer, Jan (referee) ; Zima, Jiří (advisor)
Propyl gallate (PG) is a significant synthetic antioxidant and preservative. Its determination has been studied at carbon paste electrode (CPE) using differential pulse voltammetry (DPV) and high performance liquid chromatography with electrochemical detection (HPLC-ED) and with UV spectrometric detection (HPLC-UV). Concentration dependences were measured in the media of Britton-Robinson buffer (pH 5) and methanol (20 %, v/v) by DPV and the limit of detection 0,6110-7 moldm-3 was obtained. Using HPLC with a mobile phase consisting of 0,01 moldm-3 phosphate buffer (pH 4) and methanol (50 %, v/v) with potential of working electrode E = +0,8 V and detection wavelength λ = 280 nm, concentration dependences were measured. Limit of detection was determined to 0,39 moldm-3 for HPLC-ED and 4,95 moldm-3 for HPLC-UV. After verification of the extraction procedure PG was determined in vegetable oil. The resulting value of 3,2 mgkg-1 corresponds with permited limits.
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