Strontium isotope ratio (87Sr/86Sr) has been widely used in earth science, astrochemistry, environmental chemistry, food origin tracing, archaeology and other fields. Since the 1960s, the Thermoelectric ionization mass spectrometer (TIMS) has been regarded as the benchmark technique for ratio analysis of 87Sr/86Sr with excellent accuracy and high sensitivity. Excellent sensitivity is the prerequisite for the analysis of high precision 87Sr/86Sr ratio in ultramicro samples. The key to improve the sensitivity lies in the selection of suitable emitters to improve the Sr+ yield on the surface of the metal ribbon. Mainly adopts traditional methods fluoride tantalum as launch agent, but tantalum launch agent cannot meet the ultramicro samples (pg 200) or less analysis of demand, although the new 1013 high resistance to partially compensate for the defects of insufficient sensitivity, but its narrow signal dynamic detection range, a longer decay time, correction technology of complex and expensive price limit the 1013 high resistance of the assembly and widespread application. This technical bottleneck restricts the development of related disciplines.
Recently, the institute of geology, Chinese Academy of Sciences, and earth solid isotope laboratory Li Chao peak and collaborators, professorial senior engineer found using silicotungstic acid as launch agent, to Re filament as sample carrier, which can realize ultramicro Sr samples (30-200 – pg) 87 Sr / 86 Sr analysis has high precision, compared with the traditional tantalum fluoride emission agent, silicotungstic acid has three significant advantages: improve the sensitivity, 3 times the Sr from quantum yield could reach to 16%, tantalum agent of Sr from quantum yield only ~ 5%; It is easy to prepare and purify. Silicotungstic acid is a water-soluble solid powder, which can be purified by cation resin after being dissolved in high pure water. Silicotungstate is environmentally friendly and non-corrosive, while tantalum fluoride emitter is corrosive to a certain extent, so it needs to be stable in hydrofluoric acid medium.