Sequential inductively coupled plasma quadrupole mass-spectrometric quantification of radioactive strontium-90 incorporating cascade separation steps for radioactive contamination rapid survey

摘要

Radioactive strontium-90 scattered by a nuclear power plant accident was specifically quantified by conventional inductively coupled plasma quadrupole mass-spectrometry (ICP-QMS) preceded by online chelate column separation (based on lab-on-valve) and oxygen reaction (designated the cascade step). The proposed system overcomes the isobaric interference of ~(90)Zr, whose soil concentration exceeds that of ~(90)Sr by more than six orders of magnitude. In addition, the system requires no ultimate mass spectrometry or radioactive ~(90)Sr standards. The radioactive ~(90)Sr standard was replaced with the stable isotope ~(88)Sr as a pseudo-standard. The modified ICP-QMS system yielded a precise, reproducible sharp ~(90)Sr peak in the ICP-MS profile. The elution time of ~(90)Sr was highly reproducible (RSD = 0.5%). After implementing the cascade-step, the detection limit (DU was 2.3 Bq L~(-1) (equivalent to 0.46 ppq as ~(90)Sr). Analysis of microwave-digested soil yielded a DL of 3.9 Bq kg~(-1) (equivalent to 0,77 ppq as ~(90)Sr). The ~(90)Sr from environmental contaminated soil samples collected from areas at a distance of 10 and 20 km from the Fukushima Daiichi nuclear power plant ranged from 52 Bq kg~(-1) to 73 Bq kg~(-10, with no statistical difference between the proposed and general methods at 95% confidence level. The proposed method offers an attractive alternative use for ICP-other ionization mass spectrometry as an enrichment or purification step, thereby expanding the scope of ICP-mass-spectrometric analysis.