A study was conducted to determine the precision of the overall method including both the prepolymer synthesis and the analysis. Seven prepolymer samples were prepared from TDI and 1968 g/mol PPG (“Voranol” brand) at a molar ratio within 0.005 of 0.500. The average a value, or limiting percent conversion was 85.4 with a standard deviation of 2.3. The average b value was 113.2 min with a standard deviation of 13.3 min. The average of the concentration ratio of the ABABA to the ABA was 0.236 with a standard deviation of 0.032. The average of the concentration ratio of the ABABABA to the ABABA was .0.205 with a standard deviation of 0.041. The larger error associated with the last value is undoubtedly a result of the difficulty in completely resolving the chromatography peaks for the oligomers higher than ABABABA. Nevertheless, all of these measured standard deviations suggest that this method is adequately precise for many mechanistic or kinetic studies