A Novel Approach for the Determination of the Ge Isotope Ratio Using Liquid-Liquid Extraction and Hydride Generation by Multicollector Inductively Coupled Plasma Mass Spectrometry

In this work, a method for the accurate and precise determination of the Ge isotope ratio in synthetic water and natural samples of geological origin using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) with hydride generation was developed. The method was based on the liquid-liquid extraction of Ge to eliminate all elements affecting the generation of germanium hydrides. The standard-sample bracketing method was used to correct instrumental bias. Registration of analytical signal in time-resolved mode gave way to choose signals with best parameters and improved the precision of the results. Controlling the pH by using acetic buffer boosted the sensitivity by nearly five times in comparison to hydride generation methods suggested by other authors. The newly developed method is much simpler and quicker, does not need laborious Ge separation with ion-exchange resins, and thanks to its superior sensitivity, allows measurements of the Ge isotopic ratio in materials with relatively low Ge content. Delta values of the Ge-74/Ge-70 isotope ratio were measured in standard reference materials for which reference values were available in the GeoREM database. We demonstrated that the accuracy and precession of this method are equally good or better than methods proposed by other authors.

Automated summary

This study developed a new method for accurate and precise determination of the Ge isotope ratio in synthetic water and geological samples using MC-ICPMS with hydride generation. Liquid-liquid extraction of Ge and standard-sample bracketing method were used to eliminate interferences and correct instrumental bias. The method improved precision by choosing optimal signals and increased sensitivity by controlling pH with acetic buffer. The newly developed method demonstrated superior sensitivity and accuracy compared to other methods.