Plz refer the following links. Hope this should help
are tris Cl and tris HCl are same?
i think it is just the usage of PH dependent buffer solution. HCl makes the Tris PH value under 7. I hope this could help....
For Tris-base you add HCl for adjusting pH
University of the Punjab
Central Manchester University Hospitals NHS Foundation Trust
Emre Can Tüysüz
Florida International University
Lalan Kumar Arya
Madurai Kamaraj University
University of Science Malaysia
Centre for Cellular and Molecular Biology
Federal University Wukari, Nigeria
Korea Advanced Institute of Science and Technology
Samir Al Jbour