New LC-MS Method Detects Growth Hormone Releasing Peptides in Human Urine for Doping Control

Growth Hormone Releasing Peptides (GHRPs) are synthetic secretagogues that stimulate the body's natural production of growth hormone (GH). Due to their anabolic and performance-enhancing effects, GHRPs are strictly prohibited in sports by the World Anti-Doping Agency (WADA). The challenge lies in developing robust and sensitive analytical methods to detect these peptides and their often-short-lived metabolites in biological samples, especially urine, which is crucial for effective anti-doping efforts. This study addresses the critical need for improved analytical methods capable of reliably identifying GHRPs and their major metabolites in human urine for doping control.

The developed LC-MS/MS method demonstrated excellent analytical performance for all targeted GHRPs and their metabolites. The limits of detection (LOD) ranged from 50 pg/mL to 200 pg/mL for parent compounds and 100 pg/mL to 500 pg/mL for metabolites, making it highly sensitive for doping control. Mean recovery rates across all analytes were consistently high, ranging from 78% to 93%, indicating efficient extraction. Intra-day and inter-day precision were both below 10% relative standard deviation, confirming the method's reliability. The method successfully identified GHRP-2 and GHRP-6 and their primary metabolites in urine samples, with detection limits as low as 50 pg/mL, offering a significant improvement over existing techniques. Specificity was confirmed by the absence of significant matrix interference from endogenous compounds in urine, with no false positives observed in 100 blank urine samples tested. The linearity of the calibration curves was excellent, with correlation coefficients (R^2) consistently above 0.995 across the tested concentration ranges.