Identification of Microplastics in Plastic Bottled Drinking Water Using Laser-Induced Breakdown Spectroscopy (LIBS) and Raman Spectroscopy

Abstract

Microplastics contamination in drinking water is a growing concern globally as reported in recent papers. Here we report an investigation on the identification and classification of microplastics present in bottled drinking water using Laser induced breakdown spectroscopy, and Raman spectroscopy. Different brands of bottled drinking water from different manufacturers were sampled for this investigation in Kenya. Rapid classification and identification of microplastics polymer types presence in the sampled water was done with Laser-Induced Breakdown Spectroscopy, and Raman Spectroscopy. The two techniques were used to determine molecular and atomic information of various MP polymers detected using scattered signal and plasma spectra. Five polymers polyethylene terephthalate (PET), polyethylene (PE), polystyrene (PS), polypropylene (PP) and polyvinyl chloride (PVC) were successfully detected and identified in the sampled water. Among the five polymers, the most common was PE, which was observed in 5 out of the 14 samples (35.71%). The second most dominant polymer was PET, which was detected in 4 out of the 14 samples (28.57%). Three polymers, PS (14.28%) and PP (14.28%) were detected in 2 out of 14 samples each, while PVC (7.14%) was identified in 1 sample. All the particles detected had sizes ranging between 20 µm to 70 µm. The findings clearly demonstrate possible contamination of bottled drinking water with microplastics. Raman spectroscopy and Laser Induced Breakdown spectroscopy (LIBS) are promising techniques for detection and identification of microplastics in bottled drinking water.