基于氧反应模式的ICP-MS/MS高灵敏测定食品中痕量镍

Highly sensitive determination of trace nickel in food by inductively coupled plasma tandem mass spectrometry based on oxygen reaction mode

提出了电感耦合等离子体串联质谱(ICP-MS/MS)法测定食品中痕量Ni的策略。食品样品经微波消解后采用ICP-MS/MS分析。在MS/MS模式下,分别采用O_(2)和NH_(3)/He为反应气体,利用Ni^(+)与反应气发生质量转移反应消除质谱干扰。虽然在2种反应模式下均能将质谱干扰消除至接近背景水平,但研究表明,采用O_(2)为反应气,将Ni^(+)转化为NiO^(+)进行测定获得的灵敏度更高,检出限(LOD)更低。通过理论计算与实验验证揭示了Ni^(+)与O_(2)的质量转移反应机制。在优化条件下,Ni的LOD低至11.5 ng/L。通过分析标准参考物质,并与采用国标GB 5009.138-2017法结果进行对比分析,评价方法的准确性。结果显示,在95%的置信度水平,本方法结果与国标法无显著性差异,相对标准偏差(RSD)为2.8%~4.7%,2种方法的测定值与标准参考物质的认证值基本一致。

A new strategy for the determination of trace Ni in food by inductively coupled plasma tandem mass spectrometry(ICP-MS/MS)was proposed.The food samples were analyzed by ICP-MS/MS after microwave digestion.In the MS/MS mode,O_(2) and NH_(3)/He were used as reaction gases,respectively,while Ni^(+)was used to undergo mass shift reactions with reaction gases to eliminate spectral interference.Although the spectral interference can be eliminated to near the background level in both reaction modes,using O_(2) as a reaction gas in the MS/MS mode to convert Ni^(+)into NiO^(+)could provide a higher sensitivity and a lower limit of detection(LOD).The mass shift reaction mechanism of Ni^(+)and O_(2) was revealed through theoretical calculation and experimental verification.Under the optimized conditions,the LOD of Ni was as low as 11.5 ng/L.The accuracy of the method was evaluated by analyzing the standard reference materials and comparing them with the national standard GB 5009.138-2017 method.The results showed that at the 95% confidence level,there was no significant difference between the analytical results of this method and those of the national standard method,and the relative standard deviations(RSDs)were 2.8%-4.7%.The measured values of two analytical methods were basically consistent with the certified values of standard reference materials.