Figure 5.

Metabolite (left) and lipid (right) identification according to the proposed guidelines of the metabolomics society (A–G) using the examples of leucine and a PC 18:0/16:2(7E,11Z)[R]. The lowest annotation level corresponds to known accurate mass information (G) followed by a known compound class (F), known compound sum formula (E), known functional moieties (D), known structure (isoleucine)/double bond position (PC 18:0/16:2(7,11) (C), known diastereomer (B), and the highest level to enantiomer-specific identification (A). *in lipidomics¹⁰⁵ 3 intermediate steps are distinguished at level D: sum of carbon and double bond number for all fatty acyl chains (PC 34:2)/known distribution (PC 18:0_16:2) and known position of the fatty acyl chains (PC 18:0/16:2).