The first step for metabolomics is the preparation of a sample which is used in the form of soup. For metabolomics, a number of metabolites should be determined for measurement. A fixed set of metabolites of our interest may be studied by using a targeted metabolomics approach, and if we want to study a maximum number of metabolites as many as possible, then the untargeted metabolomics approach is employed, and comparative analysis of samples is done without any bias.