Determination of synthetic phenolic antioxidants and their metabolites in water samples by downscaled solid-phase extraction, silylation and gas chromatography-mass spectrometry.
The development and performance evaluation of an analytical method dedicated to the comprehensive determination of the most relevant antioxidants and their metabolites in aqueous environmental samples is presented. This was achieved by a miniaturised solid-phase extraction (SPE) with 10mg Oasis HLB cartridges, which allow to achieve a concentration factor of 200, reducing organic solvent wastes (1 mL of ethyl acetate suffices for complete elution) and SPE costs and eliminating the need for solvent evaporation that otherwise compromises the recoveries of butylated hydroxytoluene (BHT) and 2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione (BHT-Q). Analytes were then determined by gas chromatography-mass spectrometry (GC-MS) after derivatisation with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) in a single run. BHT-d(7) and n-propyl-paraben-d(4) (PrP-d(4)) were used as surrogate internal standards. These surrogates allowed obtaining relative recoveries in the 80-110% range for all analytes even with complex wastewater samples and LODs at the 2-44 ngL(-1) level taking into account blank issues often associated to antioxidants analysis. The method was applied to sewage and river waters, showing that the seven analytes could be detected in raw wastewater. BHT and BHT-Q were the most concentrated species in that type of sample (in the 275-871 ngL(-1) range). On the other hand two metabolites of BHT, 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) and 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH) appeared to be the most ubiquitous species, being found in all samples in the 10-150 ngL(-1) concentration range.
Rodil
Rosario
R
Department of Analytical Chemistry, Nutrition and Food Sciences, IIAA - Institute for Food Analysis and Research, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Quintana
José Benito
JB
Basaglia
Giulia
G
Pietrogrande
Maria Chiara
MC
Cela
Rafael
R
D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D002083:Butylated Hydroxyanisole / Q000032:analysis* / Q000737:chemistry; D002084:Butylated Hydroxytoluene / Q000032:analysis* / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D045483:Rivers / Q000737:chemistry; D012680:Sensitivity and Specificity; D012722:Sewage / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification
D000975:Antioxidants; D012722:Sewage; D014874:Water Pollutants, Chemical; D002084:Butylated Hydroxytoluene; D002083:Butylated Hydroxyanisole