流动注射-电喷雾电离-飞行时间质谱法测定氟乙酰胺精确质量及其在毒饵大米中的应用

探讨了以对甲苯胺为质量定标物 ,采用流动注射 -电喷雾电离 -飞行时间质谱 (FI-SEI-TOF-MS)技术测定剧毒鼠药氟乙酰胺精确质量的快速筛选方法。用水提取毒饵大米中的氟乙酰胺 ,提取液在 40 0 0 r/ min下离心 5 min,取 0 .1 0 m L上清液用水稀释至 0 .5 0 m L ,进样 2μL样品溶液进行 TOF-MS检测。以 p-甲基苯胺(正离子质量 1 0 8.0 81 3 u)为锁定质量时测量的氟乙酰胺精确质量为 78.0 3 5 5 u± 1 mu。在 78.0 3 5 5 u± 1 0mu范围内仅有 C2 H7NS(正离子质量 78.0 3 77u)可能产生质量干扰 ,但其可由 M+2的同位素峰判断区别。氟乙酰胺 -对甲基苯胺峰面积比与氟乙酰胺浓度在 1 0～ 1 5 0 mg/ L成线性关系 ,相关系数 >0 .99。排除干扰后 ,该方法具有检测精确质量 ,质量误差 <1 mu、对氟乙酰胺检测专属性强、简便快速等特点 ,空白大米不干扰检测 ,可定量测定氟乙酰胺含量大于 1 5μg/ g的毒饵大米。从样品处理到质谱检测可在半小时内完成。

Determination of Fluoroacetamide Exact Mass by Flow Injection-Electrospray Ionization-Time of Flight Mass Spectrometry and Its Application in Rice Bait

A rapid method for determination of fluoroacetamide(FAA) exact mass by flow injection-electrospray ionization-time of flight-mass spectrometry was set up. FAA in rice bait was extracted by water and the extract was centrifuged at 4 000r/min for 5min. 0.1mL supernatant was diluted to 0.5mL by water. Inject 2μL for TOF-MS determination of FAA exact mass using p-toluidine(positive ion 108.081 3u) as lock mass. The determined FAA exact mass was 78.035 5u±1mu. The only mass interference within 78.035 5u±10mu is C 2H 7NS(positive ion 78.037 7u) and the difference can be discriminated by (M+2) isotope peak. The area ratio(FAA/p-toluidine) vs concentration of FAA is linear within the range of 10~150mg/L, linear correlative coefficient are higher than 0.99. The method is simple, specific and rapid. There were no interferences in blank rice. The method can be used for quantitative determination of FAA>15mg/kg in rice bait. It would take about half an hour to finish the procedure from sample preparation to TOF-MS detection.