A new purge and trap headspace technique to analyze low volatile compounds from fluid inclusions of rocks and minerals

作者：Mulder Ines^*; Huber Stefan G; Krause Torsten; Zetzsch Cornelius; Kotte Karsten; Dultz Stefan; Schoeler Heinz F

来源：Chemical Geology, 2013, 358: 148-155.

DOI：10.1016/j.chemgeo.2013.09.003

• Dynamic headspace purge and trap technique
• Mineral grinding
• Fluid inclusions
• Carbon tetrafluoride
• Sulfur hexafluoride
• Methyl chloride

A new method for the analysis of trace gases from fluid inclusions of minerals has been developed. The purge and trap GC-MS system is based on the system described by Nolting et al. (1988) and was optimized for the analyses of halogenated volatile organic compounds (VOCs) having boiling points as low as -128 degrees C (carbon tetrafluoride). The sample preconcentration cold trap consists of a U-shaped glass lined steel tube (GLT (TM)), that is immersed into a small liquid nitrogen Dewar vessel for cooling. A rapid desorption step heats up the preconcentration tube in %26lt;30 s from -196 degrees C to 200 degrees C. The process is carried out by using a pressurized air stream to dissipate the liquid nitrogen followed by resistive heating of the trap. The design of the cold trap and the direct transfer of desorbed analytes onto the GC column via a deactivated capillary column retention gap made sample refocusing within the GC oven unnecessary. Furthermore, a special air-tight grinding device was developed in which samples ranging from soft halite (hardness 2, Mohs scale) to hard quartz (hardness 7) are effectively ground to average diameters of 1000 nm or below, thereby releasing gases from fluid inclusions of minerals. The gases are then purged from the grinding chamber with a He carrier gas flow. The detection and quantitative determination of gases, such as SF6 and CF4 released from fluorites and CH3Cl from halite samples is demonstrated.

• 出版日期2013-11-4