A Practitioner's Dilemma Mass Spectrometry-Based Annotation and Identification of Human Plasma and Urinary Polyphenol Metabolites.

The practitioner's dilemma in metabolite assignment can be described as follows: for compound and metabolite identification, strict guidelines should be followed using authentic standards only, or uncertainties in structure assignment of compounds with the certainty of consequential errors should be accepted. These uncertainties arise due to limitation of software and databases in combination with the complexity of the human body fluid samples.