Fig. 4From: Advances and key considerations of liquid chromatography–mass spectrometry for porcine authentication in halal analysisInternal pG + fragments are represented by the product ions at m/z 171.076, which are extremely characteristic of collagens. Internal a, b, and Ɣ ions were the most commonly observed pieces. Kleinnijenhuis et al. (2018) Copyright (2018) with permission from ElsevierBack to article page