Doping control analysis of selected peptide hormones using LC–MS(/MS)

With the constantly increasing sensitivity and robustness of liquid chromatography–mass spectrometry-based instruments combined with enhanced reproducibility as well as mass accuracy and resolution, LC–MS(/MS) has become an integral part of sports drug testing programs particularly concerning the detection of peptide hormones. Although several of the relevant peptidic drugs such as insulins (Humalog LisPro, Novolog Aspart, etc.), growth hormone releasing peptides (GHRPs, e.g., GHRP-2, GHRP-6, Hexarelin, etc.), and insulin-like growth factors (e.g., IGF-1, IGF-2, long-R3-IGF-1) are currently analyzed using dedicated top-down analytical procedures, i.e. employing specifically tailored sample preparation procedures followed by targeted LC–MS(/MS) measurements focusing on intact analytes, first approaches towards multi-analyte methods have been established. These allow the determination of the prohibited substances in blood and urine doping control specimens following therapeutic applications. In addition, the use of new complementary devices such as ion mobility analyzers, e.g., in hybrid mass spectrometers yielded promising data for the differentiation of isobaric insulins, which outlines the potential to further accelerate and multiplex doping control analytical assays to meet the continuously increasing demands of rapid and unambiguous test methods. Moreover, the potential of LC–MS/MS to target recombinant peptide hormones such as human growth hormone using bottom-up approaches has been demonstrated by targeting proteotypic peptides that unambiguously differentiate the recombinant molecule from the naturally occurring and endogenously produced analog.