Power spectrum produced using data from the entire XMM-Newton observations (0.3–12 keV). The upper continuous line represents the power threshold for detection of periodicity at a 3σ c.l., according to the method described by Israel & Stella (1996). We also show in the bottom part of the plot a second continuous curve that represents the upper limit calculated with the same method, on the presence of pulsations from IGR J18410-0535 as a function of the frequency. The two dashed lines represent the 5% and 10% upper limit levels on that curve. The most stringent upper limit we could provide with this method is 6–10% for frequencies in the range 0.02–6.8 Hz.