Development and application of SPE-UHPLC-MS/MS methods for quantification of 29 steroids in rat serum.

Steroids and their metabolites play crucial roles in reproductive health, endocrine diseases, and tumor development. Comprehensive analysis of these compounds is essential for both mechanistic investigations and clinical evaluations. Although comprehensive analytical methods have been established for steroids in human clinical samples, their direct application to rat specimens remains limited, particularly with the absence of validated methods for detecting certain hydroxylated steroid metabolites in vivo. This study developed highly sensitive solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry methods for the quantitative analysis of 29 steroid metabolites. Through optimized derivatization of steroids and integration of two-dimensional liquid chromatography techniques, the method effectively reduces interference from non-volatile salts and overcomes trace-level detection challenges. Method validation demonstrated a wide linear range (0.002-250 ng/mL), low limits of quantification (2-100 pg/mL), high accuracy (88-114%), and precision (intra- and inter-batch CV ≤14%). The method exhibited acceptable extraction recovery, matrix effects, and stability, confirming compliance with regulatory standards. The validated method was successfully applied to characterize serum steroid metabolic profiles in both N-methyl-N-nitrosourea-induced breast cancer and ovariectomized rat models, revealing alterations in estrogen 2-hydroxylation and pregnenolone 21-hydroxylation pathways mediated by key steroidogenic enzymes, including CYP1A1/CYP1B1 and potentially CYP21A2-independent mechanisms, providing robust support for preclinical research on steroid-related diseases.