Sensitive Analysis of Nitroguanidine in Environmental Matrices by LC-MS

Anna Voloshenko Rossin, The Casali Center, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel (anna.voloshenko@mail.huji.ac.il )
Sergey Sladkevich, The Casali Center, The Institute Of Chemistry, The Hebrew University Of Jerusalem, Jerusalem, Israel
Guy Gasser, The Casali Center, The Institute Of Chemistry, The Hebrew University Of Jerusalem, Jerusalem, Israel
Irena Pankratov, Israel Water Authority, Bet Dagan, Israel
Ovadia Lev, The Casali Center, The Institute Of Chemistry, The Hebrew University Of Jerusalem, Jerusalem, Israel

Nitroguanidine (NQ) is a nitramine explosive, which is often used as a double- or triple-based propellant. NQ is an environmental contaminant that is refractory, persistent and highly mobile in aqueous systems and soils. The large production rate, the high mobility and its stability make this compound a potential risk to underground water resources. The low retardation in the ground implies that it can also serve as a potential indicator for propagation of aquifer pollution plumes created by the military industry.

NQ cannot be easily extracted from water, and thus the sensitivity of all of the current analytical techniques is rather limited. Most of these methods have low sensitivity (LOD >100 µg/L), and lack specificity due to the UV detection. The most sensitive method for NQ analysis employs UPLC-MS, and reported LOD is of 0.7 µg/L (Mu et al, Anal. Chem. 2012, 84, 3427).

In this research, we present a new methodology for determination of NQ based on reduction of NQ to aminoguanidine (AQ) by hydrogenation on zinc under acidic conditions, followed by derivatization by 4-nitrobenzaldehyde (4-NBA) (Scheme 1), which can be pre-concentrated on C18 SPE cartridge prior to LC-MS analysis.

Scheme 1. Schematic illustration of NQ reduction followed by derivatization with 4-NBA.

Demonstrated LOD reaches 5 ng/L and 22 ng/g in water and soil respectively. The method was successfully applied for NQ analysis in a contaminated industrial site.