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Chemical Separation and Mass Spectrometry of Cr, Fe, Ni, Zn, and Cu in Terrestrial and Extraterrestrial Materials by Thermal Ionization Mass Spectrometry (CAT#: STEM-ST-0196-LJX)

Introduction

A sequential chemical separation technique for Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial silicate rocks was developed for precise and accurate determination of elemental concentration by the isotope dilution method (ID). The technique uses a combination of cation−anion exchange chromatography and Eichrom nickel specific resin. The method was tested using a variety of matrixes including bulk meteorite (Allende), terrestrial peridotite (JP-1), and basalt (JB-1b). Concentrations of each element was determined by thermal ionization mass spectrometry (TIMS) using W filaments and a Si−B−Al type activator for Cr, Fe, Ni, and Zn and a Re filament and silicic acid−H3PO4 activator for Cu. The method can be used to precisely determine the concentrations of these elements in very small silicate samples, including meteorites, geochemical reference samples, and mineral standards for microprobe analysis. Furthermore, the Cr mass spectrometry procedure developed in this study can be extended to determine the isotopic ratios of 53Cr/52Cr and 54Cr/52Cr with precision of ∼0.05ε and ∼0.10ε (1ε = 0.01%), respectively, enabling cosmochemical applications such as high precision Mn−Cr chronology and investigation of nucleosynthetic isotopic anomalies in meteorites.




Principle

Thermal ionization mass spectrometry exploits the thermochemical reactions that occur in molecules in a sample when they are irradiated by a beam of high energy electrons. This reaction usually takes place at high temperatures, resulting in the formation of ions. The ionized species are accelerated in an electric field and then analyzed by mass spectrometry through the ion-focusing lens of a mass spectrometer. The mass spectrometer will separate and detect the ions according to their mass and charge.

Applications

For analyzing the distribution of molecules, atoms and molecular groups.
For studying the chemical structure of Earth's minerals and rocks.
For studying the structure and function of biomolecules.
For studying problems in physics.

Procedure

1. The sampling system sends the sample to be analyzed into the ion source;
2. The ion source ionizes the atoms and molecules in the sample into ions;
3. The mass analyzer separates ions according to the size of the mass-charge ratio;
4. The detector is used to measure and record the intensity of the ion current to obtain the mass spectrum.

Materials

• Sample Type:
Cr, Fe, Ni, Zn, and Cu

Notes

Before starting the machine, check whether the water (water cooler), electricity, gas (argon/nitrogen), temperature, humidity, and exhaust air of the instrument are normal.