Microplastics are EVERYWHERE

Like many others, I’ve become much more aware of the global issue of microplastics – small (<5 mm) pieces of plastic that are littering the Earth, but where do microplastics come from? Microplastics have been found everywhere, from the Arctic sky to the deep sea. I’ve blogged previously about plastic glitter, widely used in crafts and sometimes unknowingly to decorate food, but there are so many other sources in our home. Taking the kitchen for example, I can immediately think of three potential microplastic sources:

  • Net bags for fruit – in my experience the mesh tends to partially disintegrate when opened, spreading tiny plastic pieces over the counter
  • Sponge scourers – these can shed plastic fibres from the pad during washing up
  • Washing clothes – washing synthetic clothing is estimated to generate 2,300-5,900 tonnes of fibres every year in the UK alone

While we can take steps to reduce the future release of microplastics, what about the millions of tonnes of microplastics already in the environment? We usually don’t know where they have come from, or what impact they are ultimately likely to have. Being able to identify the types of plastic present and their particle morphologies can help answer these important questions.

How can MDRS help to characterize microplastics?

Morphologically-Directed Raman Spectroscopy (MDRS) is already used in many research fields to obtain component-specific data from multi-component samples. A single automated measurement on the Morphologi 4-ID first characterizes the microplastic particle sizes and shapes in a sample, then returns to particles to chemical identify them using the integrated Raman spectrometer.

In a study looking at characterizing microplastics using MDRS, a suspension of six common plastics with a particle size below 1 mm was vacuum filtered. Particles of all six plastic types collected on the membrane filter were chemically identified and classed using the Morphologi 4-ID.

Raman spectra of PE, PP, PS, PC, PET and PVC acquired on the Morphologi 4-ID, with example particle images of each plastic-type in the filtered sample

For each type of microplastic, clear differences were seen in the particle counts, sizes and shapes. Picking two as an example, the PE particles appeared to be mostly fibrous in nature, while the less numerous, large PVC particles were more fragment-like. The size and shape will affect how the microplastic particle behaves in the environment, such as how it is transported and the potential for uptake by organisms.

If you would like to find out more about how MDRS using the Morphologi 4-ID can be used to characterize microplastics, read the application note here.