The construction of the ITS-90 gives rise to relatively small temperature differences depending on the specific interpolation equation (temperature range) used. Also the use of different thermometers gives rise to small temperature differences. These and the already published temperature differences between the ITS-90 and thermodynamic temperature lead to an additional small uncertainty in the difference between the triple point temperatures of pure Ne-22 and Ne-20. Estimates are given for the various contributions. (C) 2014 Elsevier Ltd. All rights reserved.