Determination of diaminopimelic acid in rat feces by high-performance liquid chromatography using the Pico Tag method

The purpose of the study was to develop a method for the determination of diaminopimelic acid (DAPA) concentrations in rat feces by reversed-phase high-performance liquid chromatography (HPLC) using the Pico Tag method. Precolumn derivatization with phenylisothyocyanate (PITC) and UV (254 nm filter) detection were used. Samples were hydrolysed in 6 M HCl at 110 °C for 24 h. Hydrolysates were then diluted, dried and derivatized, and samples (10 μl injected onto a 300×3.9 mm NovaPak C18 (Waters) HPLC column. Under the conditions used, DAPA eluted as one single peak between those of tyrosine and valine. On-column DAPA concentrations in standards were 41.5–83 pmol, which were in the range of the amounts present in fecal samples of rats fed semisynthetic diets. Amounts of DAPA determined in fecal samples of rats fed broad bean- or chickpea-based diets were, respectively, 2.56 and 2.98 mg g−1. The advantages of the method and the relevance of the results for nutritional studies in monogastric animals are discussed.