Medical diagnosis research is driven into the development of non-invasive diagnosis devices centered in fast and precise analytical tools and instrumentation. This led to Volatile Organic Compounds (VOCs) being identified as metabolomics biomarkers for several diseases, including respiratory infections, cancer and even COVID 19 non-invasive test. While VOCs give a direct access to physiological states, their applicability requires detections at low concentration ranges (ppbv-pptv). However, its clinical success is strongly dependent on precise and robust calibration methods. In this work we describe a calibration protocol of volatile organic compounds in low concentration range (ppbv-pptv) for analytical GC-IMS technology which offer a quick in-situ results in medical diagnosis. The calibration is based on permeation tubes which are monitored using thermogravimetric methods to estimate mass loss ratio over time establishing emitted concentrations. Notwithstanding future improvements, herein calibration methodology results are a promising step forward in medical diagnosis and applications.