Isotope Ratio Measurements by Laser Ablation ICP-MS

For direct isotope ratio measurements on solid samples, laser ablation ICP-MS (LA-ICP-MS) is applied to an increasing extent in geology, geochronology, biology and environmental research.6 

An analytical procedure has been proposed for precise uranium isotope ratio measurements in a thin uranium layer on a biological surface by LA-ICP-MS using a cooled laser ablation chamber.125 One drop of uranium isotope standard reference materials NIST, 350, NIST 930, of our isotopic laboratory standard CCLU 500 (20p.l, U concentration 200 ng 1) and of uranium with natural isotopic pattern were deposited on the leaf surface and analyzed by LA-ICP-MS at well defined laser crater diameters of 10, 15, 25 and 50 p.m. A precision for measurements of isotope ratios in the range of 2.1-1.0% for 235U/238U in selected isotope standards was observed whereby the precision and the accuracy of isotope ratios compared to the non-cooled laser ablation chamber was improved.125 

Selected applications in isotope ratio measurements by LA-ICP-MS using different equipment are summarized in Table 8.4.50,126 136 

Sample ICP-MS Laser system/ Wavelength Measured isotope ratio RSD (%) Application Reference 

Mantle sulfides MC-ICP-MS (Nu Plasma) Merchantek LUV/266 nm 187Os/188Os 187 Re/188Os 0.05-1 geochronology Pearson et aid31 

An analytical procedure has been developed for the determination of the isotope ratio 

Isotope ratio measmements were carried out by LA-ICP-MS on protein spots of a brain sample with Alzheimer s disease in two dimensional (2D) gels after tracer experiments with highly emiched Cu and Fe isotope tracers. In Figme 8.3 part of the 2D gel and the transient signals for Cu and Cu are shown. Isotope ratio measmements on protein spots did not reveal any changes of isotope abundances of Cu, whereas an enrichment of Fe was found in several protein spots in the 2D gel. The Fe/ Fe isotope ratios measmed in selected protein spots of an Alzheimer protein sample after tracer experiments are summarized in Figme 8.4.  

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