n this project, a new soft ionization device for mass spectrometry is presented using the flexible microtube plasma under controlled atmospheric conditions. The controlled atmosphere flexible microtube plasma consists of the plasma source itself connected to a gas chromatograph and a mass spectrometer using a borosilicate glass crosspiece. Controlled atmosphere, for example, nitrogen and/or an oxygen mixture, is introduced to the system to create a clean ionization environment. Reproducibility issues are discussed, and solutions are presented manipulating the gas flow in the crosspiece. A proof of concept is shown using a ketone mixture introduced to the mass spectrometer to optimize atmospheric conditions. Furthermore, application of the presented device for the sensitive and non fragmenting ionization of volatile organic biomarkers relevant for cancer is carried out. Sample treatment for human saliva is described, and relevant candidate biomarkers are measured in the saliva matrix, showing a very good ionization efficiency and neglectable matrix effects with limits of detection below 80 ppt. Last but not least, this project will allow to obtain a powerful tool for cancer diagnosis, which would have a huge impact on society. Early cancer detection presents a critical factor associated to patient survival. According to the European Union, the devastating tragedy cancer is at individual level, we must keep in mind that the combination of an ageing population and the rising costs of cancer treatments is stretching health care budgets of even the richest countries. Promoting health and prevention are cost-effective public health measures to identify new cancer cases in the early stages of development and to reduce both the risk of cancer and – this goes hand-in-hand - the burden on national health budgets. The European Commission has recently kicked-off the State of Health in the EU cycle to support the EU Member States in making their health systems more effective, accessible and resilient – so that prevention starts playing a major role and people have optimal healthcare options. BIOplasma offers an interesting tool to reach this objective.