激光烧蚀光谱-电感耦合等离子体质谱联用技术在地质分析中的应用

Laser Ablation Spectroscopy(LAS) Coupled with ICP-MS and Its Applications in Geoanalysis

激光烧蚀光谱(LAS)技术具有空间分辨率高,样品用量少,制样简单,分析速度快,可远程、实时、在线分析多相物质(气态、液态、固态)的特点,是近年来发展迅速的一种分析技术,具有广阔的应用前景,但它对痕量元素的分析能力不足。电感耦合等离子体质谱(ICP-MS)技术具有灵敏度高和多元素及同位素同时检测的能力,在微痕量元素精密分析方面具有很大的优势,但对基体元素分析存在困难。将LAS和ICP-MS技术相结合,形成LAS和LA-ICP-MS联用技术(LAS-ICP-MS),可充分利用两种技术的优势,形成互补技术,为地质分析提供一种便捷、可靠的分析手段:利用LAS技术,可预先监测样品的大致含量与信号的稳定性等参数,筛选适用于LA-ICP-MS分析的样品,避免因元素含量过高引起的LA-ICP-MS采样锥锥口易堵塞,基体效应过大,以及因样品均匀性差或激光参数未优化等因素影响分析的准确性和精密度等问题;利用LA-ICP-MS技术,可对激光进样条件和原子化、离子化条件分开进行优化,从而改善仪器的分析性能。将LAS-ICP-MS用于岩石矿物分析,表现出其良好的应用前景。

Laser ablation spectroscopy （LAS） is an elemental analysis method that requires in principle only optical access to the sample surface and can therefore be used as a real time, in-situ and remote monitoring method,with the advantages of the high space resolu- tion, the speed of analysis, the ease or absence of sample preparation, the relatively low cost, and the possibility to build portable instruments that allow real field analysis for any substances （gas,liquid or solid）. However,major restrictions are the poorer detection capabilities for trace elements compared to Inductively Coupled Plasma Mass Spectrometry （ICP- MS）. ICP-MS is a powerful,high sensitivity and low limit tool for multi-elemental and isotopic analysis. But the sample preparation consumes time and the matrix elements influence the analysis results. Combine LAS with ICP-MS to form LAS and LA-ICP-MS can comple- ment the weaknesses of these two techniques. For example,LAS can be used first to filter the samples of high contents to decrease the aggradation of the elements on the skimmer core and reduce the matrix effects,and to test the homogeneity of the samples and the sta- bility of the laser, so that to improve the accuracy and precision of the analysis. The LAICP-MS has a separated laser sampling device, which makes it flexible to optimize the parameters of atomization and ionization respectively to improve the analysis performance. LAS-ICP-MS has been employed on the analysis of rocks and minerals, which shows good application prospects.