Analytical Solutions to Microplastics and Path Forward

21 August, 2021

The extensive distribution and abundance of microplastics in the ecosystem is so evident that scientist defines it as The Plasticine: Age of Plastics. Accumulation of microplastics in the environment is also showing adverse effect on human health, so it’s very important to identify and quantify them. Particles or polymeric fibers equal to or smaller than 5 mm, about 0.2 inches, in diameter originating from sources such as plastic bottles, food packaging, toys and clothing are categorized as microplastics. Nano plastics are even smaller, with diameters less than 0.050 mm. 

Effects of Micro and Nano plastics on human health

Research on wildlife and animal models confirmed micro- and Nano plastics exposure leads to infertility, inflammation and cancer although effect on human health is still under investigation. The “World Health Organization” in its recent report has expressed great concern regarding the exposure to effects of Nano and microplastics on human health. The major entry source into the human system is represented via consumption of food or via trophic transfer, through inhalation and through skin contact while using scrubs and cosmetics that contain micro and Nano plastics. Microplastics smaller than 20µm can penetrate into organs, and those with a size of about 10 µm should be able to access all organs and cross cell membranes, blood–brain barrier, including placenta. Microplastics are characterized by a broad range of properties including size, shape, chemical composition and hydrophobicity that could cause harm to cells and tissues because of the cytotoxicity of particles. Mystery behind how toxic chemicals release from microplastics is not well known, but mechanism involved are hydrophobic interactions, pH variations, the ageing of particles, and polymer composition.

Plastics to Microplastics – Minor to Major Problems

Impacts of Nano and Microplastics on biota reported at various levels of biological organization (SAPEA, 2019) [Source]

Detection and reporting of Microplastics in human tissues

Detection of microplastics in aquatic and marine environments globally has raised scientific and public health concern. Proper reporting of microplastics is very crucial for comprehensive understanding of its impact on environment, ecology and human health. Diverse analytical instruments or multiple analytical instrumentation techniques are being used for separation, characterization and quantification of microplastics in the environment. Researchers are working on establishing methods for detection of microplastics in human tissues.
In a recent study presented at “American Chemical Society (ACS),”use of mass spectrometry technique is recommended to analyze human tissue samples which were found to have monomers, or plastic constituents, in them.

Solutions to Microplastics and path forward

1. Quantification methods for Microplastics:

  • Due to it's potential threat to environment and human health, scientific community and regulatory bodies are evaluating different techniques to establish standardized methods for the characterization of microplastics. Several analytical methods including flow cytometry, mass spectrometry, imaging techniques such as Fourier-Transform Infrared Spectroscopy (FTIR)/Laser Direct Infrared(LDIR) or Raman microscopy, to identify the polymer type and chemical analysis methods are under consideration.
  • Imaging techniques such as FTIR or Raman microscopy is to identify polymer type but have some challenges like lengthy sample preparation processes, are limited to particles >10 µm and do not provide information on concentration. Innovative analytical techniques such as Thermal Desorption (TD) of filtrates using Gas Chromatography Mass Spectrometry (GC–MS) to analyze microplastic samples, providing simultaneous polymer identification and quantitative results in a simple, time-efficient workflow.
  • TD is a GC preconcentration very effective technique to analyse volatile (VOCs) and semi-volatile organic compounds (SVOCs) in a wide range of sample matrices and part of many environmental monitoring programmes. By concentrating organic vapours from a sample into a very small volume of carrier gas, TD results in narrow chromatographic peaks, which maximises sensitivity for trace-level target compounds. Direct desorption of filtrates containing microplastics provides a simple and streamlined sample preparation approach while GC–MS analysis produces information-rich volatile organic compound (VOC) profiles. The VOC profiles contain marker compounds which helps to identify and quantify the plastic, along with other unique chemical signatures that could prove useful in source identification, distributions , toxicity assessment and profiling.

Advantages of TD-GC-MS system for microplastic analysis:

  • Sample preparation is simple, straightforward and takes significantly less time compared to other analytical techniques.
  • Manual error and sample loss is avoided by placing entire filter paper into the empty TD tube for microplastic analysis, an advantage over techniques such as pyrolysis.
  • Analysis of entire filter paper provides a larger sample for analysis making TD-GC-MS a highly sensitive analytical technique.

Direct desorption TD–GC–MS workflow  

  • Injecting authentic gas or liquid standards onto sorbent tubes, allowing for the response factors to be compared with the sample analytes to determine absolute amounts and quantification.
  • MS/MS spectra can be compared to National Institute of Standards and Technology database and helps to identify unknowns.

TD–GC–MS technique is ideal for laboratories with varying sample types and challenging matrices. Unique workflow provides an automated process for microplastics analysis and automated data processing packages make the GC–MS data straightforward to interpret.

Related Reference:

  1. United nations 2030 agenda for sustainable development includes the sustainable goal(SDG) target aimed at preventing and significantly reducing marine pollution of all kinds.
  2. G20 Implementation framework for actions on marine plastic litter aims to tackle the issue of marine plastic litter and microplastics on global scale.
  3. G7 countries & EU members noted the lack of standardized methodologies.