Tris is highly soluble in water and is useful in the pH range 7.0-9.0. It is used in the preparation of Laemmli buffer, one of the most common SDS-PAGE buffers. In addition, Tris can also be used for many custom running and loading buffers, most often with glycine and SDS.
Tris-HCl is just Tris base with an equivalent of HCl present for each molecule of Tris. So, it's essentially a version of Tris that has had its pH adjusted downwards before it even hits solution.
* Do not eat, smoke, or drink where Tris (2,3- Dibromopropyl) Phosphate is handled, processed, or stored, since the chemical can be swallowed. Wash hands carefully before eating, drinking, smoking, or using the toilet. * Use a vacuum or a wet method to reduce dust during clean- up.
Tris buffer is a good choice for most biological systems because it has a pKa of approximately 8.1 at 25°C, making it an effective buffer in the range of pH 7–9. ... However, after overshoot and readjusting with NaOH, or using Tris HCl and adjusting the pH with NaOH, there is a change in ionic strength.