High Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry for the Determination of Brevetoxin PbTx-2 in Shellfish
高效液相色谱/四极杆-飞行时间质谱测定神经性贝毒

Brevetoxin PbTx-2 was determined by high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (Q-TOFMS). Extraction from shellfish tissue was achieved with acetone, and purified by solid-phase extraction on a C18 cartridge column. Chromatographic separation was performed on a Zorbax XDB-C18 column(150 mm x 2.1 mm i.d., 3.5 microm) combined with a safeguard column (Symmetry C18, 20 mm i.d. x 3.9 mm, 5 microm) with methanol-water(85: 15, v/v) containing 0.5 mmol/L ammonium acetate as eluent at a flow rate of 0.20 mL/min. The protonated PbTx-2 molecule was selected as a precursor ion scanning for Q-TOFMS in the positive electrospray ionization mode. Average recoveries of PbTx-2 spiked to tissue homogenates through the complete cleanup procedure ranged from 91% to 94%, and relative standard deviations (RSD) ranged from 11% to 12%. The limit of quantification in shellfish tissue was 0.1 microg/g, and the limit of detection based on signal-to-noise ratio of 3 was 0.5 ng. The proposed method was used to confirm PbTx-2 in toxic shellfish. It offers a high degree of specificity because Q-TOFMS with high resolution permits accurate relative molecular mass and fragment ion measurement at no expense of sensitivity.