高效液相色谱/四极杆-飞行时间质谱测定神经性贝毒

High Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry for the Determination of Brevetoxin PbTx-2 in Shellfish

采用高效液相色谱/四极杆 飞行时间质谱(HPLC/Q TOFMS)联用技术对贝类样品中的短裸甲藻毒素PbTx 2进行了检测研究。样品经丙酮提取、C18小柱净化后,用ZorbaxXDB C18色谱柱(2 1mmi.d.×150mm,3 5μm)进行分离,流动相为甲醇 水(体积比为85∶15)溶液(含0 5mmol/LNH4Ac),流速0 20mL/min。电喷雾正离子模式,选择质子化PbTx 2分子离子[M+H]+作为前体离子进行TOFMS扫描、测定。结果表明,样品的平均加标回收率为91%～94%,相对标准偏差(RSD)为11%～12%,定量检测限为0 1μg/g,检测限为0 5ng(S/N=3)。由于Q TOFMS具有高分辨率,能进行精确质量测定而不降低灵敏度,因此该方法可作为确证分析方法。

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×2.1 mm i.d., 3.5 μm) combined with a safeguard column (Symmetry C18, 20 mm i.d.×3.9 mm, 5 μm) 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 ionizaion 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 μg/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.