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The worldwide produced plastic amount was about 314 m tones in 2013. A content of about 5-12 m tones of plastic products is estimated to attain to the environment. There, they are exposed to environmental aging conditions like UV light, abrasion, water, oxidation etc. and degrade to small particles. If the particles reach a dimension < 5 mm they are called microplastic. Today microplastic is almost ubiquitary and was found in the aquatic as well as in the terrestrial environment. The main representatives are polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalat (PET).
Analyzing microplastics in environmental samples turned out to be very challenging, due to the fact that there are only a few synthetic particles beside a huge number of natural. Furthermore, the different polymers particles vary in their shape, their density and their chemical characteristics. Until now, there is no standard procedure for sampling, concentration and analyzing. We developed a thermal decomposition method for analyzing micro plastics in environmental samples. The method is a combination of a thermal extraction on solid-phase adsorption agents with a subsequent analysis of the decomposition products by thermal desorption gas chromatography mass spectrometry. In contrast to more established methods, such as IR or Ramen spectroscopy, our method enables measurements within few hours and gives an integration result of polymer specific decomposition products. Therefore, it is possible to identify and to quantify polymers in environmental matrices.
The use of the method is demonstrated for various polymers (PE, PP, PS, PET) in spiked and first time also in real environmental samples.
The accumulation of plastics leaked into the environment achieve a high perception in the last years. It is uncontroversial that often an uncontrolled, high consumption of plastic products and a poor waste management resulted in plastic findings all over in the environment. However, less is known about the relevant pathways and fate of plastic in the environment. Especially plastic fragments smaller 5 mmm, so called microplastics, achieve a high attention, because their amount and risks arising from these fragments are still unknown. The basic mechanisms of plastic or more precise, of different polymer degradation processes are often not considered, resulting in unrealistic statements.
For generation of fundamental understanding of this problem we developed in the last years a fast thermoanalytical method for identification and mass quantification of microplastics in complex samples. The presentation will also give a short introduction about polymer degradation.
The pathways of plastics, especially of microplastic (MP), in environmental compartments, particularly in aquatic systems, are not well understood. The critical point is the lack of fast, harmonised methods for sampling, sample preparation and sample analysis. These three analytical steps are dependent on one another and must be optimised.
In recent years, we developed a method for representative sampling and fast detection of MP in aqueous systems. The sampling in different freshwater bodies is performed in the field with a fractionated filtration system using mesh sizes of 500, 100 and 50 µm. For water with an intermediate or high content of suspended particular matter a minimum of 1000 L has to be filtered. In the lab, mesh sizes of 10 and 5 µm are used for further filtration. Subsequently, the water filtrates of the different particle size classes are sterilised, dried, weighed and homogenised, if necessary.
Conventional methods for MP analysis are infrared and raman spectroscopy, giving information on the shapes and numbers of individually identified MP particles. Our focus is on the determination of mass contents of various polymers potentially contained in environmental samples. For qualitative and quantitative MP detection TED-GC-MS is used, a two-step method based on gas chromatography-mass spectrometry (GC-MS) with previous thermal extraction. This method not only enables us to screen the samples for characteristic marker-molecules, thus identifying single polymers, but furthermore allows the calculation of mass contents of individual polymers. In the present work, different freshwater compartments were exemplarily studied to identify containing polymers and calculate their mass content in MP particles.
The number of publications reporting the amount of microplastic (MP) all over the world increased rapidly. Methods used so far are very time consuming and not able to provide information on total contents. As harmonised sampling, sample preparation and analysis strategies are missing different studies can hardly be compared and quantitative data, including identification and mass contents of the polymers found, are missing. This leads to a lack of comprehensive understanding of MP occurrence, source and entry pathways into the environment.
We developed a method, Thermal Extraction/Desorption-Gaschromatography-Massspectrometry, as a fast screening method for MP analysis. Solid residues of water samples are heated up to 600 C under a N2 atmosphere without any sample preparation. The collected decomposition gases are separated in a gas chromatography system and detected in a mass spectrometer. Mass contents of the identified polymers can be calculated.
In this presentation we will show first results from the influent of the wastewater treatment plant Kaiserslautern (Germany) and its combined sewage system as possibly entry pathway. In order to determine the relevance of wastewater split streams analysis of grey water will be conducted. Samples are fractionally filtered by a sieve cascade with mesh sizes of 500, 100, 50 µm.
Tire wear particles (TW) are generated by the abrasions of tires on the road surface through traffic. These particles can be transported by air and surface runoff and might also infiltrate the soil and consequently affect terrestrial ecosystems. The estimated tire wear (TW) emissions are immense, with 1.33 106 t a-1 in Europe. Despite this, only little is known about the environmental contents or the fate of TW.
One reason for this knowledge gap is the challenging analysis of TW in environmental samples. Detection of TW with spectroscopic methods is problematic due to high fluorescence interferences caused by contained black carbon. One analytical approach is to use zinc (Zn), a typical additive in tires, as a specific marker for the quantification of tire wear. However, any Zn originating from the sample matrix must be separated beforehand and requires elaborate sample preparation.
Car tires consist partly of synthetic rubbers, such as styrene-butadiene-rubber (SBR). This SBR could be identified and quantified via Thermal-Extraction-Desorption-Gas Chromatography-Mass Spectrometry (TED-GC-MS). This newly developed and fast screening method allows the simultaneous detection of microplastics and TW mass contents and requires minimal to no sample preparation. Firstly the sample is thermally extracted in a thermobalance under a nitrogen atmosphere. The resulting specific decomposition products are sorbed on a solid phase adsorber, which is then transferred to a GC-MS via an autosampler, where the products are desorbed, separated and identified. Cyclohexenylbenzene is used as a specific marker for SBR.
Here we investigated top layer soil samples, collected at the roadside of highly frequented German highways. Samples were analyzed without sample preparation, and SBR was detected in all investigated samples in mass contents ranging from 67.2 to 2230 mg kg-1. A correlation between SBR and Zn content in the soil was confirmed, while the correlation between SBR and Corg was hardly pronounced. We successfully demonstrated the application of TED-GC-MS as a screening method for tire wear in soil samples.
The present study will discuss these analytical results in detail as well as sampling parameters like sampling depth and distance to the roadside, and the effect of the particle size on the particle transport by water runoff and air.
Results from different methods applied to micro- and nanoplastics (MNPs) analysis show that there are large gaps in harmonisation with respect to terminology, size classes, sample preparation protocols and, finally, to the comparability of the measurands and descriptors.
Within the European research cluster to understand the health impacts of micro- and nanoplastics (CUSP) working group WG3-Inter-Laboratory Comparisons an overview of the existing detection methods revealing advantages and disadvantages regarding the analytical tasks is being compiled. There is a clear need to develop high class characterized reference materials for MNPs in the size ranges of 100-10 µm and smaller than 10 µm, so that these can be used to validate methods and to make results comparable. Inter-laboratory comparisons (ILCs) on model samples with complex matrices regarding mass, or water samples for number-based methods, will help us to advance the process of harmonization as well as to train users early in process of developing new methods.
We plan to keep all five CUSP projects well-connected also with the 'outside' MNP projects and ILCs and to extract the optimum of needs, capabilities, and efforts in order to launch new VAMAS ILCs which should expand already available ones.
In this breakout session first, an introduction is given on the planning and organisation of an inter-laboratory comparison (ILC) under the pre-standardisation plattform VAMAS within the newly formed technical working area TWA 45 Micro and Nano Plastics in the Environment. An update with the ILCs on micro- and nanoplastic performed so far is also given. In the third part, the requirements for a reference materials are presented. The needs from the different H2020 micro- and nanoplastic projects are collected and compiled in an ILC matrix for joint activities as the next steps.