A Peristaltic Pump and Filter-Based Method for Aqueous Microplastic Sampling and Analysis

Abstract

Sampling the aquatic environment for microplastic concentration is inherently difficult because of variations in microplastic concentration, shape, and density and the potential for contamination. We present an assessment of a method for microplastic sampling that uses a peristaltic pump to pump water through a series of in-line stainless-steel mesh filters. Following filtration, the stainless-steel filters were treated using previously published methods to isolate microplastics, adjusted for the stainless-steel mesh filters. Microplastics were identified using micro-Fourier transform infrared (μFTIR) spectroscopy in transmission mode. This method was tested in the laboratory using standard polyethylene beads and was applied to two sample sites at the Las Vegas Wash in Nevada. The results showed that 70% of the polyethylene beads were recovered after the peristaltic pump and laboratory steps with minimal blank contamination. The advantages of the peristaltic pump sampling method are it (1) supports a range of sample volumes, (2) reduces sample handling, (3) reduces the potential for contamination, (4) provides flexibility in sampling locations, and (5) supports a variety of filter types. Using stainless-steel mesh filters allows for (1) streamlined and direct field-to-laboratory sample processing, (2) μFTIR transmission mode analysis of filter-mounted microplastics, and (3) reduced filter and sample processing costs.

Improved microplastic processing from complex biological samples using a customized vacuum filtration apparatus

“…The structural integrity of the stainless steel filters remained intact during μATR‐FTIR, and IR measurement of MPs were of a consistent spectral quality returning an average 98% spectral match to control MPs (analyzed by ATR‐FTIR) and 98% to the corresponding reference polymer in the Nicodom library. This assessment further supports the use of this substrate in MPs research (Harrold et al 2022), and used in conjunction with the stainless steel filtration apparatus offers a plastic‐free protocol to process samples. In addition, the availability of prefabricated stainless steel mesh sheets with a multitude of different aperture sizes affords the option to configure the filtration apparatus in a size‐tiered z‐stack formation facilitating the size partitioning of MPs from complex environmental sample matrices in a single step onto a substrate compatible with downstream microphotography and μ‐FTIR.…”

Characterization of Ingested Plastic Microparticles Extracted from Sea Turtle Post-Hatchlings at Necropsy

“…The presented techniques are most applicable with larger microplastics, but addressing the throughput remains a hurdle for more efficient particle identification. Trends in current research suggest a strong interest in developing faster and more efficient analysis techniques for handling larger sets of microplastic samples [27][28][29], although the resolution for assessing small and impure samples remains a difficulty. However, if there were ways to characterize smaller samples or do real-time imaging, such as with Raman imaging, higher throughput might be achievable.…”

Preservation, storage, and sample preparation methods for freshwater microplastics – a comprehensive review

“…For instance, pumping large areas followed by sieving is the combination of bulk and volume-reduced methods used in MP studies. 44 Different sampling methods have been used considering the goals of studies in freshwater compartments, elaborated on in the following sections.…”