Rapid detection of microplastics in feeds using NIR Spectroscopy

The presence of microplastics in the forage and feedstuffs of domestic animals represents an imminent threat to the entire food chain that reaches humans as the particulates could pass the intestinal barriers contaminating blood and animal products. Until now, there is not a simple, quick, sustainable, and reliable method to detect microplastics in feeds. The objective of this work was to investigate the ability of Near- Infrared Spectroscopy to detect microplastics in ruminant feeds. Two types of instruments were tested using five feedstuffs (corn silage, mixed hay, rye grass silage, soy grain and total mixed ration). Two types of crumbled contaminants (low-density polyethylene and polystyrene) were accurately mixed at 0, 1, 3 and 5 mass mg g-1. The pool of the five matrices examined by the benchmark instrument (714-3333 nm) allowed an accuracy around 0.8 mg g-1 and a detection limit around 1 mg g-1 however, in separate calibrations, the errors could be halved. A short range of wavelength (714-1070 nm) or a smart NIRS instrument have prevented an acceptable discrimination of the concentrations. Following these preliminary results, any validation on other samples and with different and powerful NIRS tools is encouraged.