Isotope Dilution LC-MS/MS Method for Glycine Betaine in Manila Clam (Tapes philippinarum)

Glycine betaine (GB) is a natural compound with demonstrated metabolic functions in mammals and beneficial effects on the human body: it protects cells under osmotic stress, as an organic osmolyte, and acts as a methylating agent in several vital biochemical pathways. The main dietary sources of GB are vegetables, such as cereals, spinach, chard and beetroot, above all; shellfish is one of the richest animal sources. A simple method for the quantification of GB in the edible portion of Manila clams (Tapes philippinarum) was setup, using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Isotope-labelled internal standards were used during sample extraction, in order to ensure an accurate quantification. The method was successfully validated following the Commission Decision 657/2002/EC as a guideline; since GB is an endogenous compound, present in very high concentrations in the target matrix, appropriate adjustments were taken. The method developed reported very satisfying performances in terms of linearity, trueness and precision; moreover, its applicability was demonstrated on commercial pools of Manila clams.