Expert Exchange: Training on Laser Fluorination Oxygen Isotope Analysis

Europlanet 2024 RI’s Expert Exchange Programme aims to support the planetary community to share expertise and best practice, and to prepare new facilities and services. The programme provides funding for short visits (up to one week).

Hwayoung Kim of the Korea Polar Research Institute visited Ian Franchi at the Open University, UK, from 13-21 January 2024.

The three oxygen isotopes (¹⁶O, ¹⁷O, ¹⁸O) in rocks, minerals and meteorites can provide crucial
information about their origin and secondary processes that result from isotopic exchange.

As a lab technician of a laser fluorination oxygen isotope laboratory at the Korea Polar Research Institute (KOPRI), I have been conducting oxygen isotope analyses of meteorites for past three years. During this period, I have encountered challenges such as limitations in analytical precision, difficulties in analysing water-rich samples, and a lack of theoretical background. The laser fluorination oxygen isotope laboratory at The Open University directed by Dr Ian Franchi is a laboratory with extensive experience in analysing various samples and achieving high-precision measurements with over 30 years of stable operation.

The purpose of this visit is to gather a better knowledge about the laser fluorination oxygen isotope
measurement techniques, to learn more about mass spectrometer laboratory maintenance, and to
analyse in-house obsidian standard materials for an inter-laboratory comparison. Through this visit, I
aimed to exchange improvements in each other’s analysis procedures, with the expectation that this
collaboration would enhance the stability and data precision of our analysis lines.

During the 5 days, the programme was as follows:

• Day 1: Dr. Ian Franchi provided detailed explanation about their fluorination line components, laser fluorination process, oxygen purification process, analytical techniques for water-rich meteorite samples and analytical strategy for eliminating isobaric interferences using Variable Temperature Control (VTC) molecular sieve.
• Day 2: Due to a sudden problem in the mass spectrometer ion source, we had to replace ion source filament. I was able to learn how to maintain and manage a mass spectrometer without the assistance of an engineer, along with the key points necessary for its operation.
• Day 3: With Mr. James Malley we conducted optimisation processes of the mass spectrometer after replacement of ion source filament. Observing this process, I learned procedures to ensure the stability of the equipment and maintain optimal data quality. And Dr. Richard Greenwood kindly shared their safe handling procedures of BrF₅ , which is a highly toxic substance to humans.
• Day 4: We analysed an obsidian standard material using two different analytical processes: one
• following standard procedure and the other utilizing a VTC molecular sieve to minimize the presence of NF₃⁺ ions, which can significantly interfere with the analysis of ¹⁷O.
• Day 5: We had detailed and thorough discussions about data processing, methods to enhance data precision, sample-specific approaches for improved precision, analytical challenges, and strategies to overcome them.

From the visit, I was able to gain valuable information and insights that can help upgrade our laboratory line and improve data quality. Also, I found several important processes that were missing in our laboratory procedures to maintain a low blank level in the line. The followings are summary of what I have learned from this visit and I will implement in our analysis line and procedures:

• Additional purification of BrF₅ before introducing it to the reaction chamber that can lower blank level and improve analytical precision.
• Modifications to the design of the reaction chamber and sample holder to prevent the samples from popping out from the hole while lasering.
• Installation of an ultra-high vacuum gauge to monitor blank level down to 10 -6 Torr
• Introduction of a method to monitor NF₂⁺ that can help evaluating the extent of NF + interference with ¹⁷O.
• Attachment of a molecular sieve with fine-tuned temperature adjustments to separate NF + interference during ¹⁷O measurement.
• Reducing the amount of BrF₅ in the tube attached to the line for safety reasons These will be gradually applied to our laboratory equipment and procedure. During that process, we plan to stay in regular contact to exchange necessary information and updates on the progress.

I would like to say that this visit was highly successful. I had an excellent experience that help overcoming challenging issues in the laser fluorination oxygen isotopic measurements and expanding my perspective on high-precision analyses and laboratory safety. And I consider the newly formed collaborative relationship between KOPRI and The Open University to be significant and will probably provide important advances in the study of oxygen isotopes in meteorites. I’m grateful to Europlanet Expert Exchange Programme and The Open University for making this visit possible.

Expert Exchange Objectives covered by this visit: Transnational Access Training.

Find out more about the Europlanet Expert Exchange Programme.