LETTERMAN ARMY INST OF RESEARCH PRESIDIO OF SAN FRANCISCO CA
The assay described in this report was developed to verify the concentrations of nitroguanidine NGu in feed mixtures used in GLP animal studies. The target concentrations of NGu in the animal diets ranged from approximately 1 to 22 mg NGug feed. These diets were prepared using a mixture of feed premix with a much higher concentration of NGu approximately 50 mg NGug feed. The assay employs High Pressure Liquid Chromatography HPLC and is suitable for determining NGu over this entire range of concentrations. Using methylnitroguanidine MNGu as an internal standard, weighed amounts of the animal diets were diluted, filtered and analyzed by HPLC. The peak ratios were then used to quantitate the concentration of NGu in the final dilution. Sample weights and dilution factors permit the calculation of the NGu concentration in the original feed mixture.