Determination of Fluoroacetate in Poisoning Induced Blood by On-Line GPC-GC-MS with Derivatization

The blood sample was mixed thoroughly with adding acetonitrile at volume ratio of 1:1 on vortex mixer for about 3 min, and the supernatant was collected after centrifugation for 5 min. The supernatant was adjusted to pH<2 with 6 mol·mL^-1 of hydrochloric acid solution, and then solid sodium chloride was added to form supersaturated solution. After vortex for 3 min and centrifugation for 5 min, sodium carbonate, anhydrous sodium sulfate and acetonitrile solution containing 10% (φ) pentafluorobenzyl bromide were added into the supernatant, and the mixture reacted at 65℃ for 1 h. The reaction solution was passed through 0.25 μm filtration membrane and 20 μL of filtrate was put into on-line gel chromatography (GPC) to purification. The sample solution within 4.06-6.06 min was collected, in which sodium fluoroacetate was determined by gas chromatography-mass spectrometry (GC-MS) through the large volume programmed temperature vaporizer (PTV). The working curve was drawn with the blank spiked sample solution series prepared according to the above method. As shown by the results, linear relationship between values of peak area and mass concentration of sodium fluoroacetate was found in the range of 10-320 μg·L^-1, with detection limit (3S/N) of 2.9 μg·L^-1. Test of recovery was made on the blank sample by standard addition method, giving results in the range of 71.4%-80.5%, with intra-day RSDs (n=5) and inter-day RSDs (n=5) of the determined values less than 8.0%. The proposed method has been applied in a substantial criminal case and satisfactory result was obtained.