Extraction and quantification of phthalates in plastic coca-cola soft drinks using high performance liquid chromatography (HPLC)

Nurudeen Ayobami Ayofe, Peter Olusakin Oladoye and David Olaoluwa Jegede

Abstract

Benzene-1,2-dicarboxylic acid esters, also known as phthalates, are commonly used in the productions of plastics such as polyvinylchloride (PVC) plastics, nonpolymers and adhesives. Phthalates are ubiquitous compounds which are difficult to measure in drinks and foods containing trace level. Phthalates have been associated with developmental alteration and endocrine disruption. This study was aimed at identifying and quantifying concentrations of four different phthalates namely; Diethyl phthalate (DEP), Bis-(2-ethylhexyl) phthalate (DEHP), Dimethyl phthalate (DMP), Dibutyl phthalate (DBP), and diphenyl phthalate (DPhP), in plastic Coca-Cola soft drink purchased from five different strata or locations of University of Ibadan, Ibadan, Nigeria. Liquid-liquid extraction with dichloromethane was used for the extraction of the phthalates, followed by cleaned up in a silica gel column. This was followed by high performance liquid chromatographic analysis (HPLC) for quantification. The linear range of the HPLC calibration curve was 0 mg/L to 10 mg/L with a mean correlation coefficient (R2) of 0.998 and the percentage recovery was between 56 and 106%. This result indicated that DEHP had the highest concentration of 11.52±3.31 µg/mL. Heat and longer storage of plastic soft drinks increased the content of leached phthalates in the drinks; therefore consumers of plastic packaged drinks should desist from frequent intake to avoid chronic toxicity of phthalate esters.