Hydrazine (N2H4) is a known genotoxic impurity that typically needs to be controlled down to low ppm level in pharmaceutical development. Hydrazine, however, is a challenging molecule to analyze using conventional analytical techniques due to its physical and chemical properties (e.g. lack of chromophore, absence of any carbon atom, low molecular weight, high polarity and volatility).
Additionally, analysis in pharmaceutical samples commonly encounters significant interference from matrix components that greatly overshadow the response of hydrazine. This work describes a simple, accurate and sensitive reversed-phase liquid chromatography—UV derivatization method for determination of trace amount hydrazine in pharmaceutical materials featuring three prominent strategies to address the problems associated with hydrazine analysis.
First, the derivatization reaction attaches chromophores to hydrazine, which greatly increases its sensitivity by UV–vis detection. Secondly, the derivatization reaction gener-ates a lambda max that is well-shifted away from the absorption wavelengths of pharmaceutical matrix interferences. Thirdly, from a separation standpoint, the derivatization further removes matrix interference effects through chromatography by achieving higher resolution of the derivative product fromthe active pharmaceutical ingredient (API) and its related impurities for accurate quantitation for tracelevel of genotoxic impurities (GTIs). 2-Hydroxy-1-Naphthalaldehyde (HNA) was chosen as the derivatizing reagent, and the resulting hydrazone product has a maximum UV absorbance at wavelength of406/424 nm which is in the visible range.
Since most drug substance and impurities have UV absorbance ranging from 190 to 380 nm, interference from the matrix was minimized and the appropriate selectivity was obtained, the detection limit is 0.25 ppm (0.25 _g/g API). This method was validated and applied asa generic method to determine hydrazine for pharmaceutical process control and drug material release.