激光剥蚀电感耦合等离子体质谱法测定地质玻璃中铅同位素组成

Laser ablation inductively coupled plasma mass spectrometric determination of lead isotopes composition in geology glasses

将193nm准分子纳秒激光与四级杆电感耦合等离子体质谱联用,测量了国际参照物玻璃中Pb同位素丰度比。通过剥蚀NIST612,USGS和MPI-DING玻璃,探讨了利用激光剥蚀电感耦合等离子体质谱直接测定固体样品铅同位素比值的精密度及其适用范围。通过扣除Ar载气中204Hg对204Pb的同量异位素干扰,采用内标法和外标法校正LA-ICP-MS仪器的质量歧视效应,获得的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb同位素比值测量的相对误差小于±1.2%,207Pb/206Pb、208Pb/206Pb同位素比值测定的相对误差小于±0.8%。对比结果表明,采用内标法校正的结果更接近真实值。测定的Pb同位素比值的精密度与样品中Pb含量密切相关,对Pb含量大于40μg/g的样品,同位素比值206Pb/204Pb、207Pb/204Pb、208Pb/204Pb的RSD在1.0%以内,207Pb/206Pb、208Pb/206Pb的RSD在0.5%以内。大气颗粒物样品中Pb含量很高,采用LA-ICP-MS测定Pb同位素比值,能够鉴别污染来源,满足示踪的要求。

Pb isotope abundance ratios of international reference glasses were measured by a quadrupole inductively coupled plasma mass spectrometry with a nanosecond 193 nm excimer laser.Precision and availability of Pb isotope ratios in solid samples directly determined by using LA-ICP-MS were evaluated by ablating the NIST,USGS and MPI-ding glasses.Isobaric interference of 204Hg in carrier gas on 204Pb was subtracted and mass discrimination effect was adjusted by internal standard and external standard methods.The ...