Metabolic Profiling of Carboxylic Acids and Amino Acids in the Biological Fluids of Patients Diagnosed with Endometriosis Using Liquid (HPLC-UV) and Gas (GC–MS) Chromatography

Approaches to the highly sensitive determination of low-molecular-weight fatty acids and amino acids in blood serum samples of patients diagnosed with endometriosis by gas chromatography with mass spectrometric detection (GC–MS) and HPLC with a diode array detector were proposed. Conditions for the selective determination of 23 amino acids in the form of dansyl chloride derivatives by reversed-phase HPLC with spectrophotometric detection were found, and the main factors influencing the separation parameters (pH of the mobile phase, the solvent and the buffer solution, and the gradient profile) were identified. It was shown that the traditional GC determination of metabolites in the form of silyl derivatives did not provide the required sensitivity: the high volatility of derivatives already at the stage of sample preparation led to significant losses and, as a consequence, to irreproducible results. Conditions for the determination of organic acids without derivatization using GC–MS on a polar stationary phase were optimized. A procedure for preparing blood serum for analysis (precipitation of proteins and removal of lipids) and conditions for the selective separation of analytes (temperature gradient, 70−230°C) were proposed. The developed approaches made it possible to obtain characteristic profiles of organic acids in the blood serum samples of patients with endometriosis and uterine myoma (as a comparison reference group).