SMP006-P01ポスター要旨 / 日本地球惑星科学連合2011年大会（2011年5月22日～5月27日, 幕張メッセ国際会議場） / 日本惑星科学連合の許諾に基づき本文ファイルを掲

CHANG, Qing

KIMURA, Junichi

常, 青

木村, 純一

English

JAMSTEC Repository

SMP006-P01 Room:Convention Hall Time:May 25 10:30-13:00Matrix effect and calibration strategy in trace element analysis of geological glasses using193 nm excimer LA-ICP-MSQing Chang1¤, Jun-Ichi Kimura11IFREE/JAMSTECQuantifying trace elements of solid samples by LA-ICP-MS is usually based on external calibration using a reference material(typically, NIST synthetic glasses SRM 612 and 610) and a predetermined major element composition for correction of ablatedmass of the sample and calibration standard. However, chemical and physical properties difference between sample and standardmay result in considerable bias, thereby compromise analytical accuracy. Short wavelength and short pulse width of the laserbeam (i.e. recently developing trend towards DUV and femto-second laser systems) are supposed to be superior in reducing suchmatrix biases. Using a 193 nm argon fluoride (ArF) excimer laser ablation system coupled to quadrupole type-ICP-MS, we in-vestigated the elemental responses of various standard glasses ranging from synthetic (SRM 612) to naturally-sourced chemicalcompositions (GSD-1G, BHVO-2G, and BCR-2G basalt glasses). Our results showed a clear matrix effect affecting on the accu-racy of measured trace elements including REEs and HFSEs. Calibration against SRM 612 introduced analytical bias of about20% from preferred values for the basalt glasses and natural minerals. Accuracies were improved when chemically matchedstandards were used for calibration. This was also demonstrated by analyzing a set of MPI-DING naturally-sourced glasses. TheMPI-DING basalt, andesite and komatiite glasses were accurately determined by using BHVG-2G and BCR-2G basalt standards.Neither SRM 612 glass nor basalt glass standards were appropriate for the MPI-DING rhyolite, although the former gave betterresults perhaps due to similarly high silica contents. Difference in plasma mass loading of major element from different samplematrices would explain the above observations. It appears that the more silica fraction was introduced into the plasma, the higherthe sensitivity enhancement of easily ionized elements occurred. This plasma loading effect greatly affects relative elementalresponses, and it is hard to be corrected. Laser fluence apparently influences less on the relative elemental responses. Our resultssuggest that use of matrix-matched standard is one of the most practical means to achieve accurate analysis of trace elementsin geological samples by 193 nm excimer LA-ICP-MS. Glass standards with natural composition (MPI-DING and USGS glassstandards) cover a wide compositional range for geological applications (basalt, andesite, rhyolite, komatiiate etc.). However,concentrations of some elements are too low for precise calibration. Use of trace element-doped natural rock-based standardspotentially improves calibration precision. A caveat in using such the standard is its non-natural elemental abundances, whichmay additionally introduce unusual interferences on some elements.Keywords: LA-ICP-MS, trace elements, matrix effect

Matrix effect and calibration strategy in trace element analysis of geological glasses using 193 nm excimer LA-ICP-MS

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