Preliminary study for 9,10-anthraquinone residue analysis in tea-based functional beverage: GC-ECD optimization and method development

Abstract

Abstract 9,10-Anthraquinone, a possible carcinogenic compound, is recently detected above the regulated limit in tea samples sourced from Asian countries. Its occurrence is previously neglected. The European Union has set a limit of 0.02 mg/kg for anthraquinone residue in tea. The available analysis methods for anthraquinone are mostly by gas chromatography (GC) coupled with mass spectrophotometer (MS). This study was aimed to analyse anthraquinone in an infusion of tea-based functional beverage based on low volume liquid-liquid extraction followed by a GC-μECD quantification. The experiment included optimisation of GC-μECD for anthraquinone quantification. The result showed that GC-μECD was able to detect anthraquinone at 1 μg/L with good repeatability showed by %RSD of 6.68. The calibration curve at the range of 1 to 10 μg/L showed good linearity (r=0.9973). The low volume liquid-liquid extraction sample preparation was able to extract anthraquinone from the infusion samples as low as 0.67 μg/L.