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研究开发利用飞秒激光剥蚀多接收等离子体技术(fs LA-MC-ICPMS)对硅酸岩粉末压片进行原位微区Pb同位素组成准确测定的方法。研究表明常规的200目碎样无法得到Pb同位素均一的粉末压片,需要将岩石粉末研磨至2.5μm,采用无添加粘合剂压片方法,避免了Pb同位素的污染和Pb浓度的稀释;通过fs LA-MCICPMS对制成的国际岩石粉末压片进行原位微区Pb同位素分析,~(208)Pb/~(204)Pb、~(207)Pb/~(204)Pb和~(206)Pb/~(204)Pb精密度(RSD)介于0.013%~0.066%,~(208)Pb/~(206)Pb和~(207)Pb/~(206)Pb的精密度介于0.013%~0.034%。与溶液法国际参考值比较,~(208,207,206)Pb/~(204)Pb和~(208,207)Pb/~(206)Pb的准确度为-0.089%~0.057%,在2 s误差范围内一致,该方法能准确测定粉末压片中Pb同位素组成,有效节约时间、避免污染和避免粘合剂的加入。
The method of fs LA-MC-ICPMS for the determination of Pb isotopic composition in silicic rock powder tablet by in situ micro-region was studied and developed. The results show that conventional 200-mesh pieces can not get Pb isotope homogeneously, and the rock powder needs to be milled to 2.5μm. Addition of binder without tabletting method can avoid the contamination of Pb isotope and the dilution of Pb concentration. (204) Pb, ~ (207) Pb / ~ (204) Pb and ~ (206) Pb in the prepared in-situ micro-powder Pb-based composites were analyzed by fs LA-MCICPMS. The precision of Pb / ~ (204) Pb ranged from 0.013% to 0.066%. The precision of ~ 208 Pb / 206 Pb and ~ 207 Pb / 206 Pb was 0.013% ~ 0.034%. The accuracy of ~ (208,207,206) Pb / ~ (204) Pb and ~ (208,207) Pb / ~ (206) Pb was -0.089% ~ 0.057%, which was consistent with the international reference value of solution method within the error range of 2 s. The method can accurately determine the Pb isotope composition in the powder tablet, effectively saving time, avoiding pollution and avoiding adding of adhesive.