(1) Transfer 3.0 g of feedstuff sample into 25 mL solution of 2% Ammonia in MeOH and place onto Vortex 1 min, then sonicate and swirl 5 min. Pipet 10 mL of upper clear solution and transfer to a 1 ml flask, make the dryness @ 50 C by Rotatory Evaporator.
(2) Using 2 mL of MeOH and 2 mL of n-hexane to dissolve the residue, discard the upper solution, and repeat the above procedure twice. Collect the 10 mL of MeOH portion and blow with N2 to dryness @ 45℃. Dissolve the residue again with 5 mL of Ethyl Acetate, add some anhydrous sodium sulfate, and centrifuge the solution@5000rpm for 3 min.
(3) Apply Polystyrene SPE column purify the analyte: (a) Column solvation: apply 5 mL of Ethyl Acetate and 3 mL of Acetonitrile/Ethyl Acetate (1:1). (b) Interference elution: Elute Analyte by using 10 mL of MeOH/Ethyl Acetate (1:1), collect the elute. (c) Concentrate: Under 40 degree C, evaporate on a stream bath to dryness (or with Nitrogen blowing Instrument). Mixing with 0.1 mL BSTFA + 1%TMCS by using Vortex for 1 min, Heat in oven 80 C for 1 hr. Blow with N2 to dryness by Nitrogen blowing Instrument. Bring to the volume with 0.2 mL of toluene for GC-MS analysis.
GC Column: 5% Phenyl-Methylpolysiloxane 30 m×0.25 mm I.D.×0.25μm.Inlet Temp: 300℃.
Oven: Initial 150℃ (3 min), 10℃/min to 230℃ (10min)， 20℃/min to 280℃ (10min).
Carrier Gas: Helium（99.999%）1.0mL/min
Injection: 1.0µL, pulsed splitless, 50 ng on-cloumn per Inj.
EI Temp: 230℃.
MSD Interface：280℃.
EM voltage: 1506V.
Scan Rage: 30～550U.
SIM (m/z): 267、250、502，Quantitative ion 250.
Solvent Delay：5 min. ( I can not forget the accident we made @ Tech Dec-2005. How about you?).
Please let me know if this sample pre-treatment method works.
BTW, How do you valuate the Beijing 2008 Olympic Game Opening ceremony? for me, feel humble in the front of 5000-years China History.
