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 degrees C for 24 h. Hydrolysates were then diluted, dried and derivatized, and samples (10 microliter injected onto a 300x3.9 mm NovaPak C(18) (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.