An improved system and analytical method for determining oxygen isotopes in ¹⁸O-enriched water samples

Area of Science:

• Geochemistry
• Environmental Science
• Analytical Chemistry

Background:

• Hydrogen and oxygen isotopes in water are crucial for studying the water cycle, paleoclimates, and water sources.
• Specialized samples like 18O-enriched water have applications in food science, ecology, and medicine.
• Traditional methods for oxygen isotope analysis face challenges with efficiency and memory effects, particularly for enriched samples.

Purpose of the Study:

• To develop a novel analytical system and methodology for efficient and accurate oxygen isotope determination in water.
• To overcome the limitations of traditional offline H2O-CO2 equilibrium and continuous-flow techniques for 18O-enriched water.
• To provide an improved solution for analyzing oxygen isotopes in various water samples.

Main Methods:

• An in-house designed analytical system combining water equilibrium and extraction preparation units.
• Utilizing a water bath shaker to accelerate complete isotopic exchange and reduce reaction time.
• Equilibrating 3.0 mL water samples with carbon dioxide gas at 25 °C for 4 hours.

Main Results:

• Achieved high analytical accuracy (within 0.10% for USGS45 and 0.50% for IAEA-608).
• Significantly improved analytical efficiency by reducing processing time by over 10 hours compared to traditional methods.
• Successfully addressed the low efficiency and memory effect issues associated with previous techniques.

Conclusions:

• The novel system offers a preferred solution for oxygen isotope analysis in water samples.
• This method is particularly advantageous for analyzing 18O-enriched water samples.
• The improved efficiency and accuracy support broader applications in environmental and scientific research.