Acid/base extraction involves carrying out simple acid/base reactions in order to separate strong organic acids, weak organic acids, neutral organic compounds and basic organic substances. An example would be to remove caffeine from coffee. Here is a good 'click thru' explanation from the University of Alberta: http://www.chem.ualberta.ca/~orglabs/separation/Theory/theory4_1.htm

ok i will try to explain you: first some terms extraction=seperation (usually due to the different polarity-like oil and water-) acid/base extraction is a method in order to seperate substances which has different acidity. 1.st you have a polar solvent(like water) 2.nd you have a nonpolar solvent (something is not miscible water; for example ether, or chloroform... something like oil) 3.rd you have a mixture which has at least two substances.and they have diferent acidity. ok when you mix all of them. According to pH they will choose organic (nonpolar) layer or aqueous layer. And you will be able to see two diferent layers.And you can collect them to different flasks. Important thing is to have a good pH for seperation. For example one of them strong acid (maybe pH of acid is 1) other one is weaker acid (maybe pH of acid is 5) if acidity of your mixture is 3 than your strong acid will prefer aqueous layer (it will be charged -means it will be soluble in the water-)but other acid will not be soluble it will prefer organic layer.So you seperate them to different layer But Im not talking about mineral acids they should be organic acids (should have C H O)

It is where a substance is removed from a mixture of substances using an acid or base. Acids and bases are usually quite reactive, so if you use the appropriate acid or base you can apply that to the mixture and the substance you are after will react and leach out into a separate layer (usually a layer containing a solvent - a substance which your compound will be able to dissolve into, like water). Then you can pour off the unwanted leftovers and concentrate on the compound of interest. This will only work when the original mixture contains compounds that have different chemical properties, otherwise you may get a separated solution that still contains more than the compound of interest. If this is the case there are many other separation techniques available to use.