title: Development of a generic assay for the determination of total trihydroxybenzoate derivatives based on gold-luminol chemiluminescence.
abstract: A selective assay for the determination of one of the most important class of phenolic compounds, namely trihydroxybenzoates (monomeric and polymeric compounds having at least one gallate moiety) based on their enhancing effect on the chemiluminogenic reaction between gold ions and luminol is described for the first time. In the presence of trihydroxybenzoate derivatives, the light emission generated when alkaline luminol is oxidized by gold ions is amplified several orders of magnitude compared to other common phenolic compounds which exhibit minor reactivity or no reactivity at all (e.g. hydroxycinnamates, flavonols, benzenediols). Based on this property, the experimental conditions were optimized in order to enable the determination of total trihydroxybenzoates in complex mixtures without resorting to separation techniques. The method was applied to samples of different composition (teas, herbal infusions and wines) with satisfactory analytical features yielding detection limits at the 10(-7) mol L(-1) level, intra-day precision of 3.1%, inter-day precision less than 10% and recoveries between 88.7 and 97.6%. The strengths and weaknesses of the method were identified and discussed in relation to its application in real samples.
authors: Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece. dgiokas@cc.uoi.gr
authors: Dimosthenis L
authors: DL
authors: Giokas
authors: Dionysios C
authors: DC
authors: Christodouleas
authors: Ioanna
authors: I
authors: Vlachou
authors: Athanasios G
authors: AG
authors: Vlessidis
authors: Antony C
authors: AC
authors: Calokerinos
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D017022:Flow Injection Analysis; D005504:Food Analysis; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000032:analysis; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D062385:Hydroxybenzoates / Q000032:analysis* / Q000737:chemistry; D008163:Luminescent Measurements; D008165:Luminol / Q000737:chemistry*; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature; D014920:Wine / Q000032:analysis
chemical_list: D000975:Antioxidants; D062385:Hydroxybenzoates; D010636:Phenols; D013501:Surface-Active Agents; D008165:Luminol; D005707:Gallic Acid; D006046:Gold