Characterization of plastic micro particles in the Atlantic Ocean seashore of Cape Town, South Africa and mass spectrometry analysis of pyrolyzate products

The microplastic particles with 29 pyrolyzate compounds of marine water samples from the seashore locations in Cape Town, South Africa were analysed using Pyrolysis- GC-TOF-MS. The mass spectra data documented the presence of various chemical groups that include alkanes, alkenes, dienes, fatty acids and esters, biphenyl and benzene (along with derivatives). Out of 16 identified polymers in the study area, polythene (PE) was the dominant in six out of seven locations with 87.5% followed by polyethylene terephthalate (PET) and polyvinylchloride (PVC) in five (71.4%) and four (57.1%) out of seven locations respectively. The other constituent polymers of microplastics identified through pyrolyzates were polystyrene (PS), polyamide 12 (PA-12) polyacrylic acid (PAA) and ethyl vinyl acetate (EVA) copolymer. The microplastic samples contained six additives predominantly in the family of fatty acid esters and nine plasticizers from alcohols, carboxylic esters and acids. The base peaks of m/z 41, 43, 55, 57, 69, 73, 91, 102, 105, 127 and 154 were characterized respectively with the fragmented species of C₃H₅⁺, C₃H₇⁺, C₄H₇⁺, C₄H₉⁺, C₅H₉⁺, C₃H₅O₂⁺, C₇H₇⁺, C₃H₁₀O₂⁺(McLafferty ion), C₈H₉⁺, C₈H₁₅O⁺ and C₁₂H₁₀⁺. Accordingly to Globally Harmonized System (GHS) of hazard classification, about 27.4% of pyrolyzates are Irritants, 31.4% of pyrolyzates found to be Irritants along with other hazards such as Flammable, Compressed Gas, Environmental Hazard, Corrosive, Health Hazard, Acute Toxicity and Allergy. About 41.2% of the pyrolyzates are not classified under the Irritant category. Characterizations of the plastic microparticles from the seven seashore locations such as FTIR, SEM with EDX and TGA were also done and discussed to understand the functional groups, surface morphology with elemental composition and stability respectively of the polymeric microparticles.