Spectroscopic and Voltammetric Determination of Bisphenol a Exposure to Polycarbonate Plastic Users

Abstract

Recently endocrine disorders have become a big concern. Endocrine-disrupting chemicals are contaminants interfering with hormone biosynthesis, metabolism, or change how the endocrine system works. Bisphenol A is an endocrine disruptor having weak estrogenic activity and the body easily mistakes it for the native estrogen. Continued use of products made using bisphenol A exposes user to risk of exposure above thresh hold levels leading to endocrine disruption. Polycarbonate containers are known to be major sources of bisphenol A that leaches to the container’s content through hydrolysis. This study aimed at monitoring levels of bisphenol A exposure to polycarbonate users through two novel techniques namely Spectrophotometric and Voltammetric techniques. The polycarbonate samples used were baby feeding bottles and portable water bottles. The Spectroscopic method employed a diazotization reaction procedure while the voltammetric one involved monitoring electrochemical response to varying bisphenol A concentration on a multiwalled carbon nanotube modified gassy carbon electrode. Polymer classification was done using Fourier transform infrared spectroscopy. The Fourier transform infrared spectra of thin plastic solids were identified by scanning between, 500-4000 cm-1 for characterization. The resulting spectra were compared with those of standard polycarbonate plastics reported in the literature. Characteristic polycarbonate peaks at 2970, 1970, 1504, 1187, 1013, 1079 cm-1 associated with the –C-H, C=O, C=O, O-C-O, -CH3 stretching vibrations respectively confirmed sampled bottles were polycarbonates. Temperature effect, contact time and food type on the extent of Bisphenol A leaching was determined. Microsoft Excel and Origin software 2019b were used to analyze the results. Using the diazotization technique, the bisphenol A levels for all the sampled polycarbonate bottles in the various environments ranged between 0.14 – 3.23 μg/mL. Under the voltammetric techniques, electrode modification with the multiwalled carbon nanotube enhanced the bisphenol A oxidation current signals in phosphate buffer systems by more than 50% as compared to 5.8% in the ferricyanide systems. The bisphenol A levels obtained via the voltammetric methods for all the sampled bottles subjected to different environments were in the range 0.1 – 2.3 μM. All the samples surpassed the tolerable daily intake for BPA of 4 μg/kgbw/day recommended by the European Food Safety Authority and this calls for serious consideration.