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 10mL acetonitrile and extracted with ultrasonication for 1h. Each sample was centrifuged and all liquid was collected for cleanup. After concentration by N(2) evaporation, each extract was cleaned by florisil and SDB cartridges to remove endogenous interfering compounds. Finally, each extract was filtered through a 0.2microm 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% 1.0mM acetic acid aqueous solution. Acetic acid was employed as mobile phase additive to form negatively charged adduct ions [M+CH(3)COO](-), and m/z=355 was quantified by selective ion monitoring (SIM). Overall recoveries from eggs containing 10, 50, 250 and 1000ng/g of HMX were 84.0%, 88.0%, 90.6% and 87.4%. A method detection limit (MDL) of 0.15ng/g was achieved.