ABSTRACT
This chapter attempts to gather together many of the tricks of the trade that may sometimes appear as part of a method description, but are more often applied to solve a particular problem with a particular sample. Some authors report apparent instability of drugs in deep frozen conditions. However, instability is not always distinguishable from loss of sample by other routes and it is wise to establish that there are confirmatory breakdown products present before assuming that the deep freeze conditions are inappropriate for the safe storage of samples containing a particular drug. For partial purification of biological fluids containing drugs, the most widely used procedure is still extraction into an organic solvent. Phase separation papers have been suggested, but appear to have been little used in drug analysis, although they can be very convenient. A problem the analyst often has to deal with is the formation of artifacts of drugs which subsequently result in false measurements in biological fluids.
