I'm trying to find a protocol to prepare Tris-SO₄ buffer, but I can't find one anywhere. After having not done these kinds of calculations for 8-9 years, my acid-base chemistry is pretty rusty at this point, and the Henderson-Hasselbalch equation is fuzzy at best, so I would appreciate it if someone could double check my calculations before I place any orders for chemicals. Using what I can find from Tris-HCl protocols and a clues that I can find about Tris-SO₄, this is what I figure I need to do (I'm preparing a 0.04 M solution at pH 7):

From what I can find, at 25°C, tris base has a pKa of 8.07. If I were to prepare 1L of 0.04 M of tris base, I would need to add ~0.03 moles of H⁺ to bring the pH to 7.

The H₂SO₄ stock solution that I have is 49%-51%, which is ~5.1 M. Since is completely dissociates into a strong acid, and has two H⁺ to donate, I need to add ~0.015 moles of H₂SO₄ to the 1L solution. [I am not sure if this is accurate though, as the second H⁺ dissociate from the SO₄ at a certain pH if I recall, but I'm not certain of this.]

From there, I would add NaOH or H₂SO₄ to adjust the pH to 7.

Do my calculations make sense? Or am I missing something here? Or does anyone have an established protocol for preparing tris-SO₄ that I could use? Thanks.