Laser microdissection pressure catapulting (LMPC): a new technique to handle single microplastic particles for number-based validation strategies

Abstract

This study examines laser microdissection pressure catapulting (LMPC) as an innovative method for microplastic research. Laser pressure catapulting as part of commercially available LMPC microscopes enables the precise handling of microplastic particles without any mechanical contact. In fact, individual particles with sizes between several micrometers and several hundred micrometers can be transported over centimeter-wide distances into a collection vial. Therefore, the technology enables the exact handling of defined numbers of small microplastics (or even individual ones) with the greatest precision. Herewith, it allows the production of particle number-based spike suspensions for method validation. Proof-of-principle LMPC experiments with polyethylene and polyethylene terephthalate model particles in the size range from 20 to 63 µm and polystyrene microspheres (10 µm diameter) demonstrated precise particle handling without fragmentation. Furthermore, the ablated particles showed no evidence of chemical alteration as seen in the particles’ IR spectra acquired via laser direct infrared analysis. We propose LMPC as a promising new tool to produce future microplastic reference materials such as particle-number spiked suspensions, since LMPC circumvents the uncertainties resulting from the potentially heterogeneous behavior or inappropriate sampling from microplastic suspensions. Furthermore, LMPC could be advantageous for the generation of very accurate calibration series of spherical particles for microplastic analysis via pyrolysis–gas chromatography–mass spectrometry (down to 0.54 ng), as it omits the dissolution of bulk polymers. Graphical Abstract

Nile red staining for rapid screening of plastic-suspect particles in edible seafood tissues

“…Consequently, spiking food matrices with solid MP carriers like salt tablets as opposed to particle dispersions should be considered in the future. Another promising approach for number-based sample spiking was described by Hildebrandt et al [ 38 ] using laser microdissection pressure catapulting. The method demonstrated the capability to transfer exact particle numbers down to singular particles of PE, PET, and PS ranging between 10 and 16 µm in size.…”

“…2.4.1). The sample holder was then stored in a Petri dish for transport and analysed with LDIR imaging [ 15 , 38 ]. Hereby, the size fractions 10–100 µm and 100–5000 µm were analysed separately using the Clarity Software (Version 1.5.58, Agilent Technologies Inc., Santa Clara, USA).…”