The use of graphite for the removal of oxygen from nitrogen purge gas in high temperature microthermometry using the Linkam TH1500 stage
The use of graphite for the removal of oxygen from nitrogen purge gas in high temperature microthermometry using the Linkam TH1500 stage (in Proceedings of the Eleventh European symposium on Fluid inclusions research (ECROFI XI), Benedetto De Vivo (editor) and Pierfranco Lattanzi (editor))
European Journal of Mineralogy (October 1992) 4 (5): 865-871
Gas compositions attained inside the heating chamber of a Linkam (super (Registered trademark)) TH1500 heating stage in the temperature interval 400 to 1341 degrees C were measured with a quadrupole mass analyzer. A small ring of spec, pure carbon was placed inside the chamber, and the system continuously purged with commercial grade nitrogen gas. Effective burning of C, converting trace amounts of O (sub 2) in the purge gas to CO (sub 2) and probably also to CO, occurred at temperatures above 600 degrees C, where a steady state was approached in less than 2 minutes. Based on measurements of gas compositions and inferences about mass balance, the maximum partial pressure of oxygen at 1300 degrees C was estimated at 10 (super -17) bar. In order to minimize deposition of volatile salts derived from natural samples in the optical pathway of the stage during ordinary microthermometric runs, the gas circulation pattern was slightly modified.