Microplastics Analysis by FTIR and Raman
Simplify microplastics testing and accelerate your research.
Our use of plastics in everyday items and manufacturing processes has resulted in a deluge of slowly degradable materials entering our environment and our food chain. As plastics breakdown into tiny particles (<5 mm diameter) the consequences on human, animal and ecosystem health need to be studied.
Learn about our FTIR and Raman spectroscopy solutions that can help you identify, characterize, and quantify microplastics from a variety of sample sources (bottled water, ocean water, industry waste streams) without being a spectroscopy expert.
Small particles. Big impact.
Beaches, clothing, bottled water, fish, beer, the air and honey all have one thing in common. They each contain microplastics.
Less than 5 millimeters in size [1], these confounding microparticles are an urgent concern as they invade food chains and slip through purification systems undetected. Microplastics are small plastic fibers and particles that originate from everyday objects. Sources [2] of these microplastics include:
- Clothes
- Paints
- Tire dust
- Plastic litter ( bags, bottles, straws)
- Personal care products (microbeads)
Of the tested tap water worldwide, 83% is polluted with microplastic fibers as small as 1/10th of a millimeter [3]. These fibers are dispersed into the environment through everyday activities such as doing laundry, swimming, walking in the streets, or cleaning your face. These microparticulates then end up in freshwater lakes, rivers, municipal treatment plants, and ultimately tap water. These sources affect not only our oceans, lakes, and springs, but the life of organisms that inhabit them. Figure 1 shows an analysis of microplastics from a sample of ocean water collected from the Pellestrina beach in the Lagoon of Venice. All three particles identified in box B have a size between 5 to 10 μm. The yellow particulates were identified as polypropylene, and the grey particulate was identified as PV23 Hoechst Laser pigment.
Entering your local convenience store, you assume purified bottled water is free from harmful particles. Surprisingly, bottled water is no exception to microplastics contamination and, in fact, has higher contamination than tap water. Research at the State University of New York at Fredonia showed that 93% of tested bottled water had microplastics contamination [4]. This has prompted the World Health Organization (WHO) to evaluate all available research on microplastics to help understand whether a lifetime of eating and drinking microplstics could have an effect on human health. Unfortunately, microplastics are not being detected in water purification systems, so they can come from the tap water sources as well as being created from the machinery during the bottling process. This presents a potential liability risk for beverage companies who are just now exploring how best to measure microplastics in their products.
Uncanny health effects
The impact to human health of microplastics contamination is currently unknown as the discovery is relatively new. This means we must find ways to study the composition and prevalence of microplastics as well as their biological and toxicological effects on humans.
As plastic waste breaks down in our environment, it becomes smaller and smaller and turns into fibers. These fibers can absorb toxic chemicals found in the water, such as plant pesticides or pollution from commercial ships. The microplastics then enter the food chain as organisms consume them, transferring these toxins into their bodies. These toxins translocate up the food chain until they are served on our plates. [5]
Although the impact of this toxin transmission from microplastics to fish to humans has yet to be studied, we do know the health effects toxins have on fish and small organisms. The consequences of toxin-sorbed microplastics ingested by fish can be two fold; exposure can be physical, causing tissue damage, or they can be chemical, resulting in bioaccumulation that causes liver toxicity. [2, 7]
Microplastics analytical problem
To distinguish these microparticles, the current strategy is to use a stereo-microscope and tediously separate microplastics from other materials. [6] Unfortunately this visual method is prone to errors due to the extremely small size (<1 mm) of microplastics and the potential for human error and sample contamination. This near-impossible and time-consuming identification process leaves us with a challenging problem.
The United States Environmental Protection Agency (EPA) held a Microplastics Expert Workshop in June 2017 to identify and prioritize the information needed to understand the risks and impact that microplastics pose to human life and our ecosystems.[6] Of all the needs identified for understanding microplastics risks, the expert group agreed that we need to standardize sample collection, extraction, quantification and characterization of polymers at the micron scale (≥1 µm and ≤1 mm in size). These methods would need to be reproducible, representative, accurate, and precise, while following appropriate quality assurance/quality control (QA/QC) practices. Then the information obtained on microplastic shape, polymer type, size, chemical composition and number of particles in a sample can be used to determine what is truly relevant to human and ecological health. The group supported using complementary analytical methods with visual methods and recommends instruments that can accommodate automation and calibration to assure reproducible results from person to person. [6]
The analytical solution
Raman and infrared microscopy can provide the proper identification of a wide range of microplastic particles (1-5000 µm diameter) collected from environmental, industrial, municipal or consumer-product samples. These techniques use the ability of light to interact with molecules causing them to vibrate at given frequencies. As a result, a spectrum (or a peak pattern of absorbed or emitted frequencies - Figure 2) can provide a “molecular fingerprint” of a microparticulate, providing the identity of its components.
For particles >1 μm, the Thermo Scientific DXR2xi Raman Imaging Microscope offers the analytical power to discern microplastics from other contaminants with high-spatial resolution down to 0.5 µm. The multivariate analysis algorithms of the Thermo Scientific OMNIC Software allows for spectral identification across a spectral library of plastics and polymers. The DXR2xi Raman Microscope has autoalignment and calibration capabilities to ensure accurate measurements and consistency between operators, supporting recommendations made by the EPA working group. This microscope quickly images large surface areas across the sample filter, making it a fast, reliable method for comparing multiple particulates and identifying their chemical components. For microplastic particles >10 μm, the Thermo Scientific Nicolet iN10 MX FTIR Imaging Microscope offers similar chemical imaging capabilities with speed and efficiency.
References
- https://marinedebris.noaa.gov/sites/default/files/publications-files/TM_NOS-ORR_30.pdf
- https://orbmedia.org/stories/Invisibles_plastics
- https://www.theguardian.com/environment/2017/sep/06/plastic-fibres-found-tap-water-around-world-study-reveals
- https://orbmedia.org/stories/plus-plastic/
- https://www.theguardian.com/lifeandstyle/2017/feb/14/sea-to-plate-plastic-got-into-fish
- https://www.epa.gov/trash-free-waters/microplastics-expert-workshop-report
- https://www.nature.com/articles/srep03263
The sample workflow diagram in Figure 3 shows a typical process, from sample preparation to microplastics analysis.
Citations
Find peer reviewed publications using FTIR and Raman spectroscopy for microplastics analysis.
| Title | Year | Publication and Link | Preview Text |
|---|---|---|---|
| Organic pollutants in microplastics from two beaches of the Portuguese coast | 2010 | Marine Pollution Bulletin (Volume 60, issue 11, pp 1988-1992) | “Identification of polymers was made according to standards in the Nicolet spectrometer database” |
| Occurrence of microplastics in the coastal marine environment: First observation on sediment of China | 2015 | Marine Pollution Bulletin (Volume 98, issue 1-2, pp 274-280) | “Microplastics were identified by micro-FTIR (Nicolet iN10, USA) that equipped a nitrogen …” |
| Sampling, Sorting, and Characterizing Microplastics in Aquatic Environments with High Suspended Sediment Loads and Large Floating Debris | 2018 | JOVE | “Used the Nicolet iS10 FTIR Spectrometer to analyze suspect microplastics. Used the Nicolet iN5 FTIR microscope to analyze suspect microplastics.” |
| Evidence of microplastics pollution in coastal beaches and waters in southern Sri Lanka | 2018 | Marine Pollution Bulletin (Volume 137, pp 277-284) | “Nicolet iS5 FTIR spectrometer collected 16 scans per sample at a resolution of 4.0 cm−1 …” |
| Microplastics in commercial bivalves from China | 2015 | Envrionmental Pollution (Volume 207, pp 190-195) | “Verification of microplastics using μ-FT-IR. The identification was conducted out with a μ-FT-IR microscope (Thermo Nicolet iN10 MX)…” |
| A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples | 2015 | Marine Pollution Bulletin (Volume 93, pp 202-209) | “Microplastic particles on the filter paper from both the SML water and beach sand samples … each square were selected and immediately identified using the FT-IR (Thermo Nicolet FT-IR spectrometer…” |
| Microplastics in the benthic invertebrates from the coastal waters of Kochi, Southeastern Arabian Sea | 2018 | Environmental Geochemistry and Health (Volume 40, pp1377-1383) | “The type of polymer the microplastic particles were made of was identified by the DXR Raman microscope (Thermo Scientific, USA)” |
| Abundance, size and polymer composition of marine microplastics greater than or equal to 10 μm in the Atlantic Ocean and their modelled vertical distribution | 2015 | Marine Pollution Bulletin (Volume 100, pp 70-81) | “Raman spectra were obtained via spectral measurements on a DXR Raman microscope (Thermo …)
|
| Plastics and microplastics on recreational beaches in Punta del Este (Uruguay): Unseen critical residents? | 2016 | Environmental Pollution (Volume 218, pp 931-941) | “…for polymer identification using a Raman imaging microscope (Thermo Scientific DXRxi Raman Microscope)” |
Identification of Microplastics
Webinar length: 20 minutes
This webinar covers why microplastics have become an important research topic for environmental scientists and a concern for food and beverage manufacturers. An explaination of advantages and limitations are for spectroscopy-based analytical methods will be discussed. Specifically microspectroscopy techniques (Raman and FTIR microscopy) as well as attenuated total reflectance (ATR) spectroscopy provide options for identifying unknown particles by characterizing their composition, size, and quantity. Resources are available to help make decisions on which system is best for a given application and budget.
Who should attend
- Environmental and biological researchers
- Government agency lab managers
- Food and beverage QC scientist
- Personal care QC scientists
- Analytical testing service providers
Webinar presenter:
Simon Nunn is the Business Development Manager for FTIR, Raman and NIR at Thermo Fisher Scientific. Based in Madison, Wisconsin, Simon holds a Ph.D. in Physical Chemistry from the University of Durham, UK. He has over 25 years’ experience in applications, product development and marketing and has a passion for solving analytical problems with spectroscopy.
| FTIR + ATR | FTIR + Small Spot ATR | Point-and-Shoot FTIR Microscope | FTIR Imaging Microscope | Raman Microscope | |
| Configuration |  |
 |
 |
 |
 |
| Nicolet Summit FTIR Spectrometer and Everest ATR Accessory | SurveyIR Microspectroscopy Accessory + Nicolet Summit FTIR Spectrometer | Nicolet iN5 IR Microscope + Nicolet iS20 FTIR Spectrometer |
Nicolet iN10 MX IR Imaging Microscope | DXR2 Raman Microscope | |
| Measurable Particle Size | |||||
| 5 mm | ✓ | ||||
| 1 mm | ✓ | ✓ | |||
| 500 μm | ✓ | ✓ | |||
| 100 μm | ✓ | ✓ | ✓ | ||
| 10 μm | ✓ | ✓ | ✓ | ||
| 1 μm | ✓ | ||||
| Manual Sample Placement Only | Yes | Yes | Yes | No | No |
| Automated Analysis of Filters | No | No | No | Yes | Yes |
| Immunity to Sample Fluorescence | Yes | Yes | Yes | Yes | No |
| Relative Cost | $ | $$ | $$$ | $$$$ | $$$$$ |
Common Plastics Identifiable by FTIR and Raman Spectroscopy
| Name | Acronym | Typical Density (g/cm3) |
|---|---|---|
| Expanded Polystyrene | EPS | 0.02 |
| Polypropylene | PP | 0.89 |
| Low-density Polyethylene | LDPE | 0.96 |
| High-density Polyethylene | HDPE | 0.96 |
| Acrylonitrile-butadiene-styrene | ABS | 1.05 |
| Polystyrene | PS | 1.06 |
| Polyamide (Nylon) | PA | 1.14 |
| Polymethyl methacrylate | PMMA | 1.18 |
| Polycarbonate | PC | 1.2 |
| Cellulose Acetate | CA | 1.3 |
| Polyvinyl chloride | PVC | 1.39 |
| Polyethylene terephthalate | PET | 1.39 |
| Polytetrafluoroethylene | PTFE | 2.2 |
