In-situ microbeam analyses provide unique information about elements and isotopic composition of solid substances, which is extremely helpful in resolving problems in geology, the environment and industry. Trace element geochemistry of magnetite is useful for studying physical and chemical characteristics of ore-forming environments and targeting new deposits. Analysis methods using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry ( LA-ICP-MS ) were established in this study and discussed in detail, including the selection of proper calibrating standards, the correct laser beam size and mass interference. For example, the trace element concentrations of magnetite from Ernest Henry IOCG deposit were obtained by LA-ICP-MS with NIST SRM 610 as the external standard and Fe as the internal standard. Under normal operation, beam sizes of 32 - 60 μm are good for magnetite analysis, however, smaller beam sizes (e. G 24 μm or 16 μm) are better for individual grains fine grains of magnetite. Isotopes of 49Ti,65Cu and 18Sn were measured for their respective elements Ti, Cu and Sn, respectively, in order to eliminate mass spectrometry interference.%微区原位分析提供了固体物质的元素及同位素组成的空间分布信息,有利于解决不同的地质问题、环境问题和工业方面的问题.磁铁矿中微量元素地球化学组成有助于研究成矿时的物理化学条件和示踪新的矿床.本文建立了利用激光剥蚀-电感耦合等离子体质谱( LA - ICP - MS)分析磁铁矿中微量元素的方法,探讨了选择必要的分析元素,选择合适的内标、外标,选择恰当的束斑大小等方法.以LA - ICP - MS分析澳大利亚Ernest Henry IOCG矿床磁铁矿中微量元素的方法为例,采用NIST SRM 610作为外标,Fe作为内标较为合理;正常情况下采用32～ 60 μm的激光束,但对于个别样品中磁铁矿颗粒较小,可以考虑使用较小的激光束(24 μm或16μm);为消除质谱干扰,Ti选择测量49Ti,Cu选择测量65Cu,Sn选择测量118Sn.
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