Development of a sensitive method for the analysis of four phthalates in tea samples: Tea bag contribution to the total amount in tea infusion

ABSTRACT

A sensitive, precise and selective method for the analysis of butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP) in tea samples has been applied. Molecularly Imprinted Polymer-Solid Phase Extraction (MIP-SPE) has been used for the separation and preconcentration of these compounds. Phthalates extracted by SPE were analysed by high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS). The method was sensitive (LOD < 2 µg L⁻¹), precise (RSD <10%) and accurate with recovery percentages ranging from 84% to 97%. Finally, the developed method was applied for the analysis of these phthalates in several tea samples marketed in bags. Migration studies were also performed to evaluate the concentration of phthalates released from the bags into the infusions, and teabag filters were analysed by Fourier-transform infrared spectroscopy. The migration study shows that tea filter bags contribute to the total phthalates concentration in tea infusion, and this contribution varies between 1.8 to 93.5 % of the total phthalates’ concentrations. Tea filter bags release higher DBP than BBP, DMP, and DEP.

Graphical abstract

KEYWORDS:

• Phthalates
• tea
• fourier-Transform infrared spectroscopy
• solid phase extraction
• molecular imprinted polymer
• high-performance liquid chromatography

Acknowledgments

The authors belong to the Galician Competitive Research Group ED431C2018/19. This research was partially supported by the Consellería de Educación Program for the Development of Strategic Grouping in Materials - AEMAT at the University of Santiago de Compostela under Grant No. ED431E2018/08, Xunta de Galicia. These programs are co-funded by FEDER (UE).