Dear Dr. Doube

Thank you for your message. I hope the blog we frequently publish has already been helpful and interesting.

Vaisala CO2 instruments are optimized for continuous measurement. The method you described in your question is suggested for a sample based measurement. I have few examples to share with you how our products are utilized in similar measurements:
https://www.vaisala.com/sites/default/files/documents/VIM-G-CO2-Equilibrium-sampling-Application-note-B211768EN.pdf

I know some customers using e.g. Vaisala GMP343 CO2 Probe for sample based measurements. You will find more details about the GMP343 under this link:
https://www.vaisala.com/en/products/instruments-sensors-and-other-measurement-devices/instruments-industrial-measurements/gmp343

Unfortunately, we do not have a direct solution on how to solve the syringe based sample analysis. My suggestion is to see if e.g. the GMP343 with a flow-through sampling could be utilized. The GMP343 internal measurement chamber has a volume of 59 ml ± 1 ml. The possible challenge is to ensure the whole gas volume inside the chamber is changed with the sample, and no ambient air is remaining in the actual measurement. Another product that has similar flow-through sampling but smaller chamber is Vaisala GMP252 Probe that can measure ppm-levels: https://www.vaisala.com/en/products/instruments-sensors-and-other-measurement-devices/instruments-industrial-measurements/gmp252
For %-level measurements an alternative is also available: https://www.vaisala.com/en/products/instruments-sensors-and-other-measurement-devices/instruments-industrial-measurements/gmp251

Generally speaking, the GMP343 is a high-end CO2 instrument that is normally used in similar measurements you described. I hope this would give some insight what products we could offer.