Patient saliva is collected in the collection device. To the saliva, add Phosphate buffer (pH6) and internal std for various drugs that we are testing. Clean up is through the SPE column, which involves washing with hydrochloric acid, methano/water, and eluting with ethyl acetate/methanol/ammonium hydroxide. 

Yes, we have standard drugs and prepare various calibrators for the standard curve that we prepare every day. 

The various drug panels we use include amphetamines, anticonvulsants, barbiturates, benzodiazepines, illicit drugs and opioids. 

There are lots of methods published for this. A brief literature search should identify several, and you can then filter by the HPLC column and MS system you are using. 

Try the following links to get you started

http://dx.doi.org/10.1016/j.forsciint.2004.11.027

http://link.springer.com/article/10.1007/s00216-008-2135-4

http://link.springer.com/article/10.1007/s00216-010-3903-5