Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey

Stingless bee honeys are rich in secondary metabolites such as free phenolic acids which can be easily absorbed into the body. Trace amount of the phenolic acids had made the analysis difficult, hence sample pretreatment is crucial. In this work, a graphene-magnetite composite (G-Fe3O4) was synthesi...

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Main Author:	Musa, Marina
Format:	Thesis
Language:	English
Published:	2017
Subjects:	QD Chemistry
Online Access:	http://eprints.utm.my/id/eprint/78796/1/MarinaMusaMFS2017.pdf
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spelling	my-utm-ep.787962018-09-17T04:12:56Z Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey 2017-04 Musa, Marina QD Chemistry Stingless bee honeys are rich in secondary metabolites such as free phenolic acids which can be easily absorbed into the body. Trace amount of the phenolic acids had made the analysis difficult, hence sample pretreatment is crucial. In this work, a graphene-magnetite composite (G-Fe3O4) was synthesized and assessed as an adsorbent for magnetic solid phase extraction (MSPE) of two phenolic acids namely 4-hydroxybenzoic acid (4-HB) and 3,4-dihydroxybenzoic acid (3,4-DHB) from honey samples prior to analysis using high performance liquid chromatography with ultraviolet-visible detector (HPLC-UV/Vis). Characterizations of G-Fe3O4 were performed using Fourier transform infrared spectroscopy (FTIR), low vacuum scanning electron microscopy (LVSEM) and nitrogen adsorption analysis. Several MSPE parameters affecting the extraction of these two phenolic acids were optimized. Optimum MSPE conditions were 50 mg of G-Fe3O4 adsorbent, vortex rotational speed of 1600 rpm, 5 min extraction time, 30 mL sample volume at pH 0.5, 200 μL methanol as desorption solvent (5 min sonication assisted) and 5% w/v NaCl salt. Matrix-matched calibration was used for the analysis of the two phenolic acids from several honey samples. Calibration graphs were linear in the range 1–50 μg/g (R2 = 0.9997) for 4-HB and 3–50 μg/g (R2 = 0.9996) for 3,4-DHB. The limit of detection (LOD = 3S/N) calculated for 4-HB and 3,4-DHB was 0.08 μg/g and 0.14 μg/g, respectively. Good relative recoveries (72.6-110.6%) were obtained for both phenolic acids from honey samples with RSD < 6.0% (n = 3). The developed G-Fe3O4 MSPE method was applied to the analysis of both phenolic acids in honey samples from Johor Bahru, Johor. Two Trigona spp. honey samples (H1 and H2) and a commercial honey sample (H3) were used in this study. The amount of 4-HB and 3,4-DHB in H1 sample were 0.14 ± 0.9 μg/g and 0.67 ± 1.7 μg/g honey, respectively. H2 sample showed slightly higher amount of both phenolic acids (0.47 ± 3.1 μg/g for 4-HB and 1.61 ± 2.3 μg/g for 3,4-DHB). The amount of 4-HB and 3,4-DHB extracted from H3 sample was below the LOD of the developed method. The developed G-Fe3O4 MSPE method offered is simple, environmental friendly and efficient for extraction of phenolic acids from honey samples. 2017-04 Thesis http://eprints.utm.my/id/eprint/78796/ http://eprints.utm.my/id/eprint/78796/1/MarinaMusaMFS2017.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:108746 masters Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QD Chemistry
spellingShingle	QD Chemistry Musa, Marina Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
description	Stingless bee honeys are rich in secondary metabolites such as free phenolic acids which can be easily absorbed into the body. Trace amount of the phenolic acids had made the analysis difficult, hence sample pretreatment is crucial. In this work, a graphene-magnetite composite (G-Fe3O4) was synthesized and assessed as an adsorbent for magnetic solid phase extraction (MSPE) of two phenolic acids namely 4-hydroxybenzoic acid (4-HB) and 3,4-dihydroxybenzoic acid (3,4-DHB) from honey samples prior to analysis using high performance liquid chromatography with ultraviolet-visible detector (HPLC-UV/Vis). Characterizations of G-Fe3O4 were performed using Fourier transform infrared spectroscopy (FTIR), low vacuum scanning electron microscopy (LVSEM) and nitrogen adsorption analysis. Several MSPE parameters affecting the extraction of these two phenolic acids were optimized. Optimum MSPE conditions were 50 mg of G-Fe3O4 adsorbent, vortex rotational speed of 1600 rpm, 5 min extraction time, 30 mL sample volume at pH 0.5, 200 μL methanol as desorption solvent (5 min sonication assisted) and 5% w/v NaCl salt. Matrix-matched calibration was used for the analysis of the two phenolic acids from several honey samples. Calibration graphs were linear in the range 1–50 μg/g (R2 = 0.9997) for 4-HB and 3–50 μg/g (R2 = 0.9996) for 3,4-DHB. The limit of detection (LOD = 3S/N) calculated for 4-HB and 3,4-DHB was 0.08 μg/g and 0.14 μg/g, respectively. Good relative recoveries (72.6-110.6%) were obtained for both phenolic acids from honey samples with RSD < 6.0% (n = 3). The developed G-Fe3O4 MSPE method was applied to the analysis of both phenolic acids in honey samples from Johor Bahru, Johor. Two Trigona spp. honey samples (H1 and H2) and a commercial honey sample (H3) were used in this study. The amount of 4-HB and 3,4-DHB in H1 sample were 0.14 ± 0.9 μg/g and 0.67 ± 1.7 μg/g honey, respectively. H2 sample showed slightly higher amount of both phenolic acids (0.47 ± 3.1 μg/g for 4-HB and 1.61 ± 2.3 μg/g for 3,4-DHB). The amount of 4-HB and 3,4-DHB extracted from H3 sample was below the LOD of the developed method. The developed G-Fe3O4 MSPE method offered is simple, environmental friendly and efficient for extraction of phenolic acids from honey samples.
format	Thesis
qualification_level	Master's degree
author	Musa, Marina
author_facet	Musa, Marina
author_sort	Musa, Marina
title	Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
title_short	Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
title_full	Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
title_fullStr	Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
title_full_unstemmed	Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
title_sort	graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2017
url	http://eprints.utm.my/id/eprint/78796/1/MarinaMusaMFS2017.pdf
_version_	1747818073410240512

Graphene-magnetite as magnetic solid phase adsorbent for extraction of 4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid in stingless bee honey

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