Direct method for Ra-226 analysis in water samples using ICP-QQQ-MS

Area of Science:

• Environmental Science
• Analytical Chemistry
• Nuclear Science

Background:

• Radium-226 (Ra-226) is a naturally occurring radioactive isotope found in water.
• Accurate determination of Ra-226 is crucial for assessing water safety and environmental impact.
• Existing methods for Ra-226 analysis can be complex, time-consuming, or lack sufficient sensitivity.

Purpose of the Study:

• To develop and validate a direct, highly sensitive method for Ra-226 determination in natural water.
• To establish a method suitable for routine analysis and compliance with regulatory standards.
• To demonstrate the accuracy and reliability of the proposed method through proficiency testing.

Main Methods:

• Utilized Inductively Coupled Plasma - Triple Quadrupole Mass Spectrometry (ICP-QQQ-MS), specifically the Agilent 8900 instrument.
• Employed a direct determination approach without requiring reaction gases or complex separation procedures.
• Controlled matrix effects and sensitivity instability by spiking samples with Ra-226.

Main Results:

• Achieved a highly sensitive direct determination of Ra-226 with a detection limit of approximately 0.1 fg g⁻¹ (3.6 mBq kg⁻¹).
• The method's detection limit is tenfold lower than the EU Directive limit for drinking water (40 mBq kg⁻¹).
• Demonstrated method's accuracy and precision through successful analysis of an IAEA proficiency test water sample.

Conclusions:

• The developed ICP-QQQ-MS method provides a simple, fast, and highly sensitive approach for direct Ra-226 determination in natural waters.
• The method's performance surpasses existing alternative direct methods and meets stringent regulatory requirements.
• This validated method is readily implementable for routine analysis and environmental monitoring.