In conclusion, a mass balance analysis of a known contaminated HP product was performed. On freeze drying, the contaminated vial contained 54.8 ± 0.3 mg of dry weight comprised of 11.4 ± 0.5 mg of NaCl and 0.9 ± 0.5 mg of residual benzyl alcohol (added excipients), 30.5 ± 0.5 mg was HP, 9.3 ± 0.1 mg was OSCS and 1.7 ± 0.3 mg was DS. No other contaminants or impurities were detected. The detection limit of the primary assay used to close mass balance, weighing (± 0.1 mg on an ~10 mg sample), is insignificant in our mass balance analysis compared to the recovery yields. Furthermore, the application of NMR, carbazole assay (with a limit of detection of 1 μg) and disaccharide analysis by HPLC-MS (with a limit of detection of 1 ng of disaccharide) confirmed that no significant contaminants or impurities were overlooked or missed in these analyses. This method can prospectively applied to determine many other types of potential contaminants present in HP.