One of the most common SPs for analyzing nitrogen-containing UDMH transformation products 207 is the polar phase . However, for polar SP, reference experimental RI is available for 208 approximately 10,000 compounds, which is several times less than for non-polar SP . This fact makes 209 identification very difficult in the absence of standards, which makes RI prediction for polar SP an 210 important task. Table shows that there are even fewer known retention indices on the polar phase for the UDMH 215 transformation products than for the nonpolar phase. We also found discrepancies in retention indices 216 with the available data for 3,5-dimethylpyrazole and 3-methylpyrazole. Zellner et al. reported that 217 the reproducibility of retention indices between different laboratories was usually within 10 -50 index units for polar phases. They stated that the large range of units for polar columns could be related to the heterogeneity between columns manufactured by different companies, the misuse of the gas chromatographic technique, a possible reactivity between the analyte and the stationary phase, and the absence of an analytical reproducibility, as most publications do not report data on analysis performed in duplicate or triplicate. The total absence of RI values for such classes of substances as triazoles, pyrazoles and, to a lesser extent, imidazoles results in predicted RIs, even for simple molecules, being significantly different from the experimental ones, although the patterns of their retention are preserved. This is particularly evident for the substituted triazoles, 3-amino-1,2,4-triazole, and 4-amino-4H-1,2,4-triazole.