Efficient extraction of small microplastic particles from rat feed and feces for quantification

Area of Science:

• Environmental Science
• Analytical Chemistry
• Toxicology

Background:

• Microplastic contamination is widespread in the environment.
• Limited research exists on microplastics in terrestrial ecosystems, specifically animal feed and feces.
• Standardized and validated methods for microplastic quantification are lacking, especially for small particles (<0.5 mm).

Purpose of the Study:

• To develop and validate an efficient protocol for microplastic extraction from laboratory rat feed and feces.
• To assess the recovery rates of specific microplastic types (polyamide and polyethylene) using the developed method.
• To quantify microplastic levels in rat feces from an in vivo study using the optimized extraction technique.

Main Methods:

• A three-step digestion protocol involving acidic (H2O2, HNO3), alkaline (KOH), and enzymatic (Viscozyme®L) treatments was employed.
• The method was validated using spiked polyamide and polyethylene microplastics in rat feed and feces.
• Pyrolysis-gas chromatography-Orbitrap™ mass spectrometry was used for the analysis of extracted microplastics from in vivo samples.

Main Results:

• The developed 72-hour protocol demonstrated high recovery rates for both polyamide and polyethylene microplastics.
• The method successfully extracted and identified microplastics from laboratory rat feed and feces.
• Environmentally relevant concentrations of microplastics were quantified in rat feces from an in vivo feeding study.

Conclusions:

• The presented three-step protocol is an effective, time-efficient, and cost-effective method for microplastic extraction from rat feed and feces.
• This validated method can contribute to harmonizing microplastic analysis in terrestrial ecosystems.
• The study provides a crucial tool for assessing microplastic exposure and its potential impact on wildlife and human health through the food chain.