Novel method of propyl gallate determination in rapeseed oil using CdSe/ZnS quantum dots

The objective of the study was to develop a CdSe/ZnS quantum dots (QD) based fluorescence method for the determination of synthetic antioxidant propyl gallate in rapeseed oil. The method is based on the CdSe/ZnS fluorescence quenching as a result of effective formation of host‐guest inclusion complexes between analyte and β‐cyclodextrin (β‐CD) coating quantum dots. The developed method was successfully applied to determine PG in rapeseed oil followed by SPE extraction of phenolic compounds. The average recovery was in the range 100.87–104.87%, what confirms the accuracy of the method. The technique developed was selective in the presence of sinapic acid, gallic acid, albumin, glucose, and methanol. The limit of detection of propyl gallate was 63 μM and quantification limit amounted to 184 μM, what allows detecting PG in rapeseed oil at the level 3.15 mg/kg in combination with proposed solid phase extraction. Practical applications : The developed method of propyl gallate in rapeseed oil determination thanks to simplicity of the measurement and relatively short time of analysis may be beneficial alternative for HPLC assay. The application of described technique includes the determination of PG in oils for the professional manufacture of heat‐treated foods, where Maximum Permitted Level is established on 200 mg/kg (according to EC regulation No 1333/2008) as well as screening detection in vegetable oils for household use, in which the use of this synthetic antioxidant is prohibited. The assay is easy to use both in industry labs as well as in research and development. The method of the determination of propyl gallate in rapeseed oil is based on the CdSe/ZnS fluorescence quenching as a result of effective formation of host‐guest inclusion complexes between analyte and β‐cyclodextrin coating quantum dots.