Here are a few pieces of information that may be useful to you
A buffer is a mixture of dissolved substances which tends to keep the pH of a solution constant when modest additions of acid and base are made to that solution.
Concentration of a solution represents the amount of solute dissolved in a given amount of solvent or solution. It is a macroscopic property and can be expressed in a variety of ways; qualitatively and quantitatively.
By Joni Frederick
QIAGEN® Bench Guide, available in PDF