The main degassing areas in S. Miguel Island (Azores Archipelago) are characterized by the presence of low temperature fumarolic emissions associated to the hydrothermal systems of Fogo and Furnas quiescent central volcanoes. The gas geochemistry monitoring programme of these volcanoes comprises regular analysis of gas discharges from the main fumaroles. The gases emitted from the fumaroles are sampled following the so-called Giggenbach methodology and the IVAR (Instituto de Investigação em Vulcanologia e Avaliação de Riscos) has facilities to detect H2O, CO2, H2S, H2, Ar, O2, N2, CH4 and He. The set of analyses from the last twenty years show variability in data from the same campaign, highlighting the importance of identifying and characterizing potential factors that may interfere with the results. In the current study two variables were tested, namely the use of different amounts of soda solution to fill in the Giggenbach bottles, and the effect of the time interval between sampling and analysis of the collected gases. Surveys were carried out at Caldeira Seca fumarole, located in Furnas Volcano, in July and September 2020, for the tests related with the soda volume. In this case, gases were collected in bottles filled with 20, 40 and 60% volume of NaOH 4M. Gas analyses using bottles filled with 20% of basic solution show higher variability, especially for some gases in the headspace (Ar, O2). Surveys for the tests associated with time were also carried out at Caldeira Seca in January 2020 and March 2021. The chemical data seem to show a positive correlation between the span time from sampling to analysis, and the resulting variability. These preliminary results show the importance of evaluate the intra-laboratorial variability and will contribute to define protocols and best practices in the IVAR laboratories, and consequently, reduce the variability in the results obtained. Additional tests are ongoing to evaluate variability associated to the analytical procedures.