Validation of an optimised protocol for quantification of microplastics in heterogenous samples: A case study using green turtle chyme

Alexandra G M Caron; Colette R Thomas; Kathryn L E Berry; Cherie A Motti; Ellen Ariel; Jon E Brodie

doi:10.1016/j.mex.2018.07.009

Validation of an optimised protocol for quantification of microplastics in heterogenous samples: A case study using green turtle chyme

MethodsX. 2018 Aug 10:5:812-823. doi: 10.1016/j.mex.2018.07.009. eCollection 2018.

Authors

Alexandra G M Caron^{1

2

3}, Colette R Thomas^{2

4}, Kathryn L E Berry^{1

3}, Cherie A Motti¹, Ellen Ariel⁵, Jon E Brodie⁶

Affiliations

¹ Australian Institute of Marine Science PM3, Townsville MC, QLD 4810, Australia.
² Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University, Townsville 4811, Australia.
³ AIMS@JCU, Australian Institute of Marine Science and James Cook University, Townsville, Australia.
⁴ SEED Science, Australia.
⁵ College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville 4811, Australia.
⁶ ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville 4811, Australia.

Abstract

Quantifying the extent of microplastic (<5 mm) contamination in the marine environment is an emerging field of study. Reliable extraction of microplastics from the gastro-intestinal content of marine organisms is crucial to evaluate microplastic contamination in marine fauna. Extraction protocols and variations thereof have been reported, however, these have mostly focussed on relatively homogenous samples (i.e. water, sediment, etc.). Here, we present a microplastic extraction protocol for examining green turtle (Chelonia mydas) chyme (i.e. ingested material and digestive tract fluid), which is a heterogeneous composite of various organic dietary items (e.g. seagrass, jellyfish) and incidentally-ingested inorganic materials (sediment). Established extraction methods were modified and combined. This protocol consists of acid digestion of organic matter, emulsification of residual fat, density separation from sediment, and chemical identification by Fourier transform-infrared spectroscopy. This protocol enables the extraction of the most common microplastic contaminants>100 μm: polyethylene, high-density polyethylene, (aminoethyl) polystyrene, polypropylene, and polyvinyl chloride, with 100% efficiency. This validated protocol will enable researchers worldwide to quantify microplastic contamination in turtles in a reliable and comparable way. •Optimization of microplastic extraction from multifarious tissues by applying established methods in a sequential manner.•Effective for heterogenous samples comprising organic and inorganic material.

Keywords: AM-PS, (aminoethyl) polystyrene; ATR-FTIR, attenuated total reflectance Fourier transform-infrared spectroscopy; Chemical digestion; Density separation; Extraction technique; Fourier transform-infrared spectroscopy; HDPE, high density polyethylene; Marine debris; PE, polyethylene; PET, poly(ethylene terephthalate); PP, polypropylene; PVC, polyvinyl chloride; Plastic contamination; Plastic ingestion; RO, reverse osmosis; SLS, sodium lauryl sulphate; Sequential protocol for extracting microplastics from heterogenous sample matrices.