Introduction. Spectroscopic analysis of urine samples from laboratory animals can be used to predict the efficacy and side effects\r\nof drugs. This employs methods combining 1H NMR spectroscopy with quantification of biomarkers or with multivariate data\r\nanalysis. The most critical steps in data evaluation are analytical reproducibility of NMR data (collection, storage, and processing)\r\nand the health status of the animals, which may influence urine pH and osmolarity. Methods. We treated rats with a solvent, a\r\ndiuretic, or a nephrotoxicant and collected urine samples. Samples were titrated to pH 3 to 9, or salt concentrations increased up to\r\n20-fold.Theeffects of storage conditions and freeze-thawcycleswere monitored. Selected metabolites andmultivariate data analysis\r\nwere evaluated after 1H NMR spectroscopy. Results.We showed that variation of pH from 3 to 9 and increases in osmolarity up to\r\n6-fold had no effect on the quantification of the metabolites or on multivariate data analysis. Storage led to changes after 14 days\r\nat 4�°C or after 12 months at -20�°C, independent of sample composition. Multiple freeze-thaw cycles did not affect data analysis.\r\nConclusion. Reproducibility of NMR measurements is not dependent on sample composition under physiological or pathological\r\nconditions.
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