Abstract: There is described a dry chemistry test element consisting of a chemistry unit and a mount that is ammonia-sensitive, wherein the mount is improved to prevent ammonia carry-over from test element to test element. The improvement is based upon the discovery that in previous test elements which were joined together using ultrasonic bonding along energy-directing ribs, ammonia carry-over was created by the leakage of ammonia from one ammonia-sensitive element to another test element. Each element had a construction of a mount that provided a gas leakage path into the viewing aperture of the bottom sheet of the mount. The elements of the invention are provided with a smooth area on the bottom sheet which is fixed to the chemistry unit with an adhesive while the rest of the mount is joined at the energy-directing ribs.