Research on the transformation of diisopropyl azodicarboxylate (DIAD) in gas chromatography and the development of its residual determination method

For the first time, an intriguing phenomenon was observed in which diisopropyl azodicarboxylate (DIAD) was converted into diisopropyl hydrazine-1,2-dicarboxylate (DIHD) during gas chromatography (GC) analysis. Subsequently, a GC method with pre-column derivatization was developed and validated for the determination of residual DIAD, using triphenylphosphine (TPP) as the derivatization reagent. The method was performed on a gas chromatograph equipped with a flame ionization detector (FID), using direct injection, an Agilent DB-5 capillary column, and a programmed temperature profile. Method validation demonstrated a good linear response for DIAD in the range of 1.057-10.57 µg/mL, with a detection limit of 0.528 µg/mL and a quantification limit of 1.057 µg/mL. The established method allows DIAD and DIHD to be determined collectively as a single analyte, both of which may be introduced during the manufacturing process. It exhibits high accuracy, sensitivity, excellent repeatability and stability, as well as a simple and rapid derivatization procedure. This method is expected to be applicable as a general approach for detecting DIAD and its structural analogues.