An Apparatus for Sample Degassing and Seallng Sample degassing and sealing into tubes is a common operation in photochemical studies. When large numbers of tubes must be prepared, as is often the ease when photochemical experiments are incorporated into the teaching laboratory, a "cow" is often used. This device permits the degassing of several samples at the same time hut usually requires the preparation of tubes containing a grease trap and necessitating extensive glassblowing services. This problem has been addressed through the design of reusable tubes.' We would like to communicate a different approach used for some time in our lab that eliminates the need for grease and a grease trap, simplifies the glassblowing required, and allows the preparation and sealing of low-cast test tubes by inexperienced students. As shown on the left side of the figure, the sample tube is a 13-X 100-mm test tube without a lip into which has been pulled arestriction toaid sealing. Sample solutions are added through a micro funnel made by pulling a capillary from a piece of tubine. ".and the tube is deeassed usinea "cow"made in our machine shoo. The desien is shown on the rieht side of the fipure. The seal is farmed u&g an "0"iing and has routinely allowed us &obtain pr&sures helow 1 X loz5tom. The "cor;" can be mounted onto the vacuum line using standard fittings with "0"rings or if a glass vacuum line is used by using a glass
' Wubbels, G. G. J. Chern.Educ. 1977,54,49. Davld E. Nlcodern and Roberto Marchiorl in~titutode Ouimica, Univerridads Federal do Rio de Jsneira Cx. Posld 1573, llha do Fundso. CT, Bloca A. CEP: 21941. Rio de Jeneiro. RJ. Brasil
282
Journal of Chemical Education
