*3.2.1 Extracted ion chromatogram*

In the extracted ion chromatogram (EIC) technique, expected metabolites are determined based on the predicted molecular masses of the metabolites. This technique first involves the acquisition of full scan in LC–MS/MS instrument and then application of ion extraction window to the acquired full-scan MS data-sets for identification of desired metabolite ion chromatogram [71]. Application of the narrow ion extraction window to the acquired MS datasets improves the sensitivity and selectivity. A narrow ion extraction window also helps in reducing false positive signals by removing the interferences from the ions outside of ion extraction window [91]. The limitation of this technique is unsuitability for the detection of metabolites with an unpredictable molecular mass.
