A rapid method for detecting rb-sr isotopes in rock samples

Abstract

The invention provides a method for quickly testing Rb-Sr isotopes in rock samples. The method is to dissolve and dilute the high-purity Rb and Sr samples from rock samples to an appropriate concentration of sample liquid by hydrochloric acid; then take an appropriate amount dilute phosphoric acid and TaF 5 The emitter is coated on the surface of the high-purity Re filament in turn, and after being evaporated to dryness, the Sr and Rb sample solutions are successively coated, and after being evaporated to dryness, it is tested by a thermal ionization mass spectrometer, and the ionization temperature is adjusted to 600-720°C, and the Rb isotope is tested first, and then Adjust the temperature of the filament to 1300°C and keep it for 2-3 minutes to burn off the trace Rb sample coating on the surface of the filament, and finally adjust the temperature of the filament to 1350-1500°C to test the Sr isotope. This method realizes the high-precision measurement of rubidium, strontium element concentration and strontium isotope ratio on the same filament, greatly improves the testing efficiency, and at the same time greatly reduces the testing cost and labor consumption, and has a wide range of applications for geochronology and geochemical tracer research prospect.

Description

technical field [0001] The invention belongs to the technical field of analytical chemistry, and in particular relates to a method for quickly measuring rubidium-strontium (Rb-Sr) element content and strontium isotope ratio testing in geological rock samples by using a thermal ionization mass spectrometer. Background technique [0002] Discovered by Hemmendinger in 1937 87 Rb with β - decay into 87 After the radioactive phenomenon of Sr, the Rb-Sr (rubidium-strontium) isotope system immediately attracted the attention of geologists. Since the 1950s, the Rb-Sr isotope system has been widely used in many research fields of earth science, such as crust and mantle evolution, magma evolution process, astrochemistry, metal deposit dating, isotope geochemistry, petrogenesis, provenance indication, etc. track and so on. [0003] The prerequisite for the above research is to simultaneously obtain high-precision Rb-Sr element concentrations, 87 Rb / 86 Sr and 87 Sr / 86 Sr isoto...

AI Technical Summary

Problems solved by technology

[0006] Although the above-mentioned traditional ID-TIMS analysis scheme has extremely high accuracy and test precision, the traditional TIMS test scheme is time-consuming, laborious, and expensive, as shown in the following aspects:

[0007] (1) The ion source of TIMS needs to be tested directly under high vacuum conditions. The sample chamber can only install limited (13-21) samples each time. After the analysis of these samples is completed, the next batch of samples to be tested is loaded. Time will consume a lot of time (>3 hours) for vacuuming

[0008] (2) The cumbersome operation steps (filament cleaning, filament spot welding, filament degassing) will consume a lot of labor and greatly restrict the working capacity of the laboratory

[0009] (3) The high-purity filament materials (Re (rhenium), Ta (tantalum), and W (tungsten)) used in the sample test are all disposable. At present, they mainly rely on imports and are expensive. A large amount of filament consumption will significantly increase the cost of the experiment.

[0010] To sum up, ID-TIMS has high test accuracy, but low test efficiency and high analysis cost

No rapid Rb-Sr test technique suitable for ID-TIMS analysis has been developed so far

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