A typical analytical separation procedure has several important steps: sample preparation, isolation, identification, quantitation, statistical evaluation and final decision. Each step is always critical to obtain correct results to fulfill the analytical purpose. In these various steps sample preparation step is required in order to isolate the desired components from some sample matrix since most instruments cannot handle the matrix directly and also it should include “clean up” procedure for complex dirty samples. This step needs to bring the analytes to a suitable concentration level that can be measured by the method for the real instrumental analysis, and this is called as “preconcentration” step. As the next step the isolation includes various chromatographic separation methods that the most appropriate one can be chosen depending on the analytes properties, for example, volatile and thermally stable compounds can be analyzed by gas chromatography (GC), and non-volatile and thermally labile compounds should be analyzed by liquid phase separations such as liquid chromatography (LC) and capillary based electrodriven techniques like capillary electrophoresis (CE) and capillary electrochromatography (CEC). By these analytical separation techniques the isolated complex mixture containing target analytes can be separated into its constituents. Identification and quantitation can be performed by a retention information combined with selective detection such as mass spectrometer (MS) to eliminate the interferences. Two additional steps can be done recently by using some computer techniques so-called chemometrix methods.