After the "base" การเก็บรักษาแบบควบคุมบรรยากาศ regime was established,the oxygen concentration for the control container was maintained at 2% while for the other two containers the concentration was further reduced by connecting them to the outlet channel of a gas mixing panel which was used to generate gas mixtures with very low oxygen concentrations until the fluorescence signal showed a dramatic increase indicating the lowest safe oxygen level.