We are vaidating a HPLC UV-VIS detector. We find a very peculiar problem. We found that when repeatible values on a single sample are recorded, the first time, we find the correct absorbance. This value falls for subsequent injections. Further there is a gradual decrease on further injections. We tried to see where the problem, we donot find any problem with the hardware of the detector. The tubes going to the flow cell are quite fine. The same setup with a different detector is working quite fine. We doubted the flow cell, the problem persists even on changing the flow. Does someone has an answer for this. We will be very thankful to you if you can guide us through the problem for a solution.