Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis

Summary

Microplastics act as vector of potentially toxic organic contaminants with unpredictable effects. This protocol describes an alternative methodology for assessing the levels of organochlorine pesticides adsorbed on plastic pellets and identifying the polymer chemical structure. The focus is on pressurized fluid extraction and attenuated total reflectance Fourier transform infrared spectroscopy.

Abstract

Plastic resin pellets, categorized as microplastics (≤5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.

Introduction

Global production of plastics is continuously rising since the 1950's to reach 311 million tons in 2014 with about 40% used in packaging¹. In parallel, increasing quantities of these materials are accumulating in the environment, which might pose a serious threat to the ecosystems². Although already reported in the 1970's, the occurrence of plastic debris in the marine environment has only received a greater attention in the past decade. Especially microplastics, plastic fragments with a diameter of ≤ 5 mm, are now recognized as one of the main marine water quality issues³.

Protocol

1. Plastic Pellet Sampling

1. Before going to the field, triple rinse all required sampling materials (e.g., tweezers and aluminum foil) with acetone or ethanol (99%). In case the material cannot be solvent-rinsed, heat it at 450 °C overnight in an oven (e.g., glassware).
   NOTE: In tourist areas, obtain information about possible beach cleaning activities that would remove most of the marine litter including microplastics. If possible, plan the sampling ahead of this operation. If sampling during the clean-up season, specify the details of this activity in the identity form (e.g., dates, clean-up method used, etc.

Results

Plastic pellets are usually found along the high and low tide lines of sandy beaches (Figure 1A). They can also stick to seagrass freshly stranded on beaches, after a storm for instance. They can occasionally be found on pebble and stony beaches in accumulation areas of stranded material.

Plastic pellets are usually easily recognizable by their shape, size and color as shown in .......

Discussion

Most studies focusing on organic contaminants associated to plastic pellets have relied on classical extraction methods of the adsorbed chemicals. The Soxhlet apparatus is the most widely used technique with typical extraction times ranging from 12 to 24 h and with high consumption of organic solvents (i.e., from 100 to 250 mL per extraction)²³. Maceration extractions require a long contact time between the sample and the organic solvent (e.g., 6 days)⁴ an.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Alpha–HCH	Dr. Ehrenstorfer, Augsburg, Germany	DRE-C14071000	H301, H351, H400, H410, H312
Beta–HCH	Fluka, Sigma-Aldrich, St. Louis, USA	33376-100MG	H301, H312, H351, H410
Lindane	Fluka, Sigma-Aldrich, St. Louis, USA	45548-250MG	H301, H312, H332, H362, H410
Endosufan I	Supleco, Sigma-Aldrich Bellefonte, PA, USA	48576-25MG	H301, H410
Endosulfan II	Supleco, Sigma-Aldrich, Bellefonte, PA, USA	48578-25MG	H301, H410
2,4'–DDD	Fluka, Sigma-Aldrich, St. Louis, USA	35485-250MG	H351
4,4’–DDD	Dr. Ehrenstorfer, Augsburg, Germany	DRE-C12031000	H301, H351, H400, H410, H312
2,4’–DDE	Dr. Ehrenstorfer, Augsburg, Germany	DRE-C12040000	H351, H400, H410, H302
4,4’-DDE	Fluka , Sigma-Aldrich, St. Louis, USA	35487-250MG	H302, H351, H410
2,4’–DDT	Dr. Ehrenstorfer, Augsburg, Germany	DRE-C12081000	H301, H311, H330, H351, H400, H410
4,4’–DDT	National Institute of Standards and Technology, Gaithersburg, USA	RM8469-4,4'-DDT	H301, H311, H351, H372, H410
n-Hexane	VWR International GmbH, Graumanngasse, Viena, Austria	83992.320	H225, H315, H336, H373, H304, H411
Acetone for HPLC	J.T.Baker, Avantor performance Materials B.V., Teugseweg, Netherlands	8142	H225, H319, H 336
FL-PR Florisil 1000mg/6mL	Phenomenex, Torrance, CA, USA	8B-S013-JCH
Fat free quartz sand 0.3-0.9 mm	Buchi, Flawil, Switzerland	37689
Gas chromatograph Hawlett Packard HP 6890 Series gas chromatograph with GERSTEL MultiPurpose Sampler MPS 2XL with ECD and FID detector	Agilent technologies, Santa Clara USA
Presure fluid extractor, Speed Extractor E-916	Buchi, Flawil, Switzerland
Solid phase extractor	Supleco, Sigma-Aldrich Bellefonte, PA, USA
Concentrator miVac DUO	Genevac SP Scientific, Suffolk UK
GC capillary column Zebron ZB-XLB (30 x 0.25 x 0.25)	Phenomenex, Torrance, CA, USA	122-1232
ATR FT-IR Spectrometer, Spectrum-Two	Perkin Elmer