The paper describes a lab test that can spot a group of synthetic growth‑hormone‑releasing peptides (including GHRP‑2) in horse or human urine. It focuses on how to extract and chemically modify the peptides so they show up better on a mass‑spectrometer, and it proves the test works in rats.

The growth hormone releasing peptides (GHRPs) hexarelin, ipamorelin, alexamorelin, GHRP-1, GHRP-2, GHRP-4, GHRP-5, and GHRP-6 are all synthetic met-enkephalin analogues that include unnatural D-amino acids. They were designed specifically for their ability to stimulate growth hormone release and may serve as performance enhancing drugs. To regulate the use of these peptides within the horse racing industry and by human athletes, a method is presented for the extraction, derivatization, and detection of GHRPs from equine and human urine. This method takes advantage of a highly specific solid-phase extraction combined with a novel derivatization method to improve the chromatography of basic peptides. The method was validated with respect to linearity, repeatability, intermediate precision, specificity, limits of detection, limits of confirmation, ion suppression, and stability. As proof of principle, all eight GHRPs or their metabolites could be detected in urine collected from rats after intravenous administration.