ИСТИНА

Determination of hydrazines by liquid chromatography in environmental samples Alexander Smolenkov*, Roman Smirnov, Oleg Shpigun and Mikhail Popik 1 Lomonosov Moscow State University, Chemistry Department, Leninskie Gory 1/3, Moscow 119991 *smolenkov@analyt.chem.msu.ru Hydrazines are extremely toxic. Hydrazine and methylhydrazines are hazardous environmental pollutant from rocket launching activity. In Russia the maximum allowed level of 1,1-dimethylhydrazine in surface and ground water is 0.5 ppb, the admissible concentration in soil is limited by 0.1 mg/kg. The development of sensitive and simple chromatographic method for hydrazines in general and 1,1-dimethylhydrazine in particular is therefore actual scientific challenge. Ion chromatography with amperometric detection (IC-AD) was proposed for the determination of hydrazines on SCX silica-based stationary phases which exhibit higher separation efficiency in comparison with polymer-based ones with ammonium acetate buffer as an eluent [1]. A complex mixture of hydrazines such as hydrazine (Hy), 2-hydroxyethyl-hydrazine, methylhydrazine (MH), 1,2-dimethylhydrazine, ethylhydrazine, 1,1-dimethy-lhydrazine (UDMH), isopropylhydrazine, propylhydrazine, 1,2- diethylhydrazine, tert-butylhydrazine and butylhydrazine (listed in order of their elution) was separated on Partisil 10 SCX (4,6×250 mm) column in 18 minutes. The LODs of IC-AD in aqueous solutions using 0.25 mL sample volume were 0.2, 0.5, and 1 μg/L for Hy, MH and UDMH, respectively. A direct IC method is quite simple technique without derivatization step and allows one to determine UDMH in soil with required sensitivity. To enhance the sensitivity a novel reagent, glyoxal, was proposed for hydrazines determination by RP HPLC with UV-detection [2]. Analytical derivatization carried on the simple one-step procedure at room temperature within 10 min. The glyoxal reacts quantitatively with hydrazines to form stable mono-hydrazones which are readily amenable to reversed-phase HPLC. Glyoxal derivatives with hydrazines exhibit strong absorption. Compared to more convenient 4-nitrobenzaldehyde glyoxal derivative with UDMH is characterized by two times more molar absorptivity coefficient. Detection limit of UDMH is 0.25 μg/L at 390 nm and with an injection volume of 0.1 mL. The suggested techniques were successfully applied for control of UDMH concentration in environmental samples. [1] A.D. Smolenkov, O.A. Shpigun., Talanta 102 (2012) 93-100. [2] R.S. Smirnov, A.D. Smolenkov, T.A. Bolotnik, O.A. Shpigun, J. Anal. Chem. 68 (2013) 837-844.