Retention of Azide Ion on Obelisc N Column

Sodium azide is a salt of weak hydrazoic acid with pKa 4.5-4.7. Sodium azide is very toxic. It is typically used as a stabilizer for aqueous solution to suppress bacteria grows. Chromatography separation is based on weak ionic interaction of the partially ionized hydrazoic acid with positively charged column surface. Additional polar interaction is a result of high acetonitrile concentration in the mobile phase.  


Column Obelisc N, 2.1x150 mm, 5 µm, 100A
Mobile Phase MeCN
Buffer AmAc
Flow Rate 1.0 ml/min
Detection UV, 250 nm


Class of Compounds  Base,  Hydrophobic, Ionizable
Analyzing Compounds Azide

Application Analytes:
Azide Ion
Hydrazoic acid
Sodium azide