Pinched Tube Method for Gas Sample Transfers

When transferring small volumes of gas samples between laboratories, cold welded, pinched copper tubes offer an inexpensive and convenient solution. In this paper, we outline the preparation, loading, transfer, and analysis methods used in a multi-campus, collaborative study under the United States Department of Energy. This gas transfer method has been utilized on samples from novel nuclear reactions, where the presence of low-mass gas isotopes is often used as an indicator of a successful reaction. Low-mass isotopic gas analysis requires careful preparation and handling to mitigate contamination, primarily resulting from air intrusion. The pinched tubes were found to be hermetic until punctured using a saddle valve prior to gas analysis with an analytical instrument. The integrity of this transfer method was proven using a Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer. We also discuss hermiticity measurements during the tube puncturing process.