本研究设计并搭建了一套热解析低温等离子体电离源(TD-LTP),与质谱联用实现了糯高粱中农药残留的快速和高灵敏检测.TD-LTP由热解析装置和低温等离子体放电源两部分组成,农药残留样品首先在热解析进样器内汽化,再由载气载带进入等离子体区域被电离.热解析进样器使LTP产生的气相等离子体与样品之间的气-固或气-液相互作用转变为气-气相互作用,大大提高了难挥发样品(如农药)的电离效率;电离源与质谱进样口之间采用同轴连接,提高了离子的利用率和传输效率.与传统的LTP电离源相比,TD-LTP电离源的灵敏度提高了8倍以上,稳定性提高了4倍.本研究对热解析低温等离子体电离源的各参数进行了优化,并与自制的矩形离子阱质谱相结合,研究了12种农药在该电离源下的特征离子.最后,将此电离源与商品化的三重四极杆质谱仪联用,对糯高粱样品中的12种农药残留进行了快速筛查,结果表明,本方法灵敏度高,可以满足食品安全国家标准规定的谷物中农药残留最大限量检测要求.%A thermal desorption low temperature plasma (TD-LTP) ionization was developed for rapid and sensitive detection of pesticides by direct mass spectrometry.The thermal desorption sampler was added in fount of the plasma generator.The sample was desorbed in the thermal desorption sampler firstly,and then the gas molecules were transported to the plasma generator by the carrier gas to be ionized.The utilization of thermal desorption sampler helps to shift the interaction of the gas phase plasma with the sample form gas-solid or gas-liquid to gas-gas,which increases the sensitivity and stability especially for non-volatile sample (e.g.pesticides) greatly compared with the traditional LTP ionization source.Under the optimal parameters of the thermal desorption LTP ionization source,the characteristic ions of 12 kinds of pesticides were investigated.Then the thermal desorption LTP ionization source was connected with the commercial ACQUITY TQD mass spectrometer to evaluate the pesticide residue level in broomcorn.
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