Development of an extraction and cleanup procedure for a liquid chromatographic-mass spectrometric method to analyze octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine in eggs

An efficient sample extraction and cleanup method was developed for determination of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in eggs. The procedure included solvent extraction of HMX from eggs followed by cleanup using florisil and styrene-divinylbenzene (SDB) cartridges. Homogenized egg aliquots were thoroughly mixed with 10 mL acetonitrile and extracted with ultrasonication for 1 h. Each sample was centrifuged and all liquid was collected for cleanup. After concentration by N₂ evaporation, each extract was cleaned by florisil and SDB cartridges to remove endogenous interfering compounds. Finally, each extract was filtered through a 0.2 μm PTFE membrane and stored for liquid chromatographic-mass spectrometric (LC-MS) analysis. Chromatographic separation was achieved on a reverse phase (RP) C18 column, with a mobile phase containing 60% methanol + 40% 1.0 mM acetic acid aqueous solution. Acetic acid was employed as mobile phase additive to form negatively charged adduct ions M + CH₃COO]⁻, and m/z = 355 was quantified by selective ion monitoring (SIM). Overall recoveries from eggs containing 10, 50, 250 and 1000 ng/g of HMX were 84.0%, 88.0%, 90.6% and 87.4%. A method detection limit (MDL) of 0.15 ng/g was achieved.