Parameter Deliberate changes %Rsd of peak area MET REPA Chamber saturation time(±20%) 24 min 2.12 2.39 36 min 1.06 0.69 Development distance from spot application (±10%) 7.7 cm 2.69 1.94 6.3 cm 1.56 1.89

Table 4: Results from the robustness study of method.