Abstract
In the current paper the analytical conditions for the determination of ten free organic acids by GC-MS are studied with the aim to establish a method for organic acid profiling in human urine to be used as a tool for the detection of metabolic or other health disorders. Studies included the GC-MS method development, the derivatization , trimethylsilylation, reaction conditions, the stability of the standard solutions during storage in the freezer, and the stability of the formed trimethylsilyl derivatives. Best results were obtainedat a derivatization temperature of 50 C, and a reaction time of 30 min. Standard solutions were stable for 22 days, derivatized samples were stable at least for 30 h when stored at −24 C. GC-MS analysis achieved sensitive determination of the organic acids under study with limits of detection ranging from0.03 mmol/mol creatinine for glutaric acid, to 0.34 mmol/mol creatinine for glycolic acid. Within-day and day-to-day assay imprecision was found satisfactory with relative standard deviations being below 10%.The developed method was successfully applied to the quantitative analysis of free organic acids in urine samples obtained from hospitalized children. Creatinine-corrected excretion rates of all analyzed organic acids were within reference intervals