Discontinuities in the spectrum are probably occurring when the instrument changes from the lamp used for the far UV measurements to the lamp used for near-UV and visible measurements. This requires the physical motion of some part of the instrument, and if it is not moving freely, it can result in irreproducible spectra with discontinuities. Another problem could be that one or both of the lamps is worn out and should be replaced. It is probably time to have the instrument serviced.

Some instruments allow you to change the wavelength at which the lamp switch occurs. If you can restrict your absorbance measurements to the region of the spectrum accessible to a single lamp, you can avoid the lamp switching problem for now.

Discontinuities in the spectrum are probably occurring when the instrument changes from the lamp used for the far UV measurements to the lamp used for near-UV and visible measurements. This requires the physical motion of some part of the instrument, and if it is not moving freely, it can result in irreproducible spectra with discontinuities. Another problem could be that one or both of the lamps is worn out and should be replaced. It is probably time to have the instrument serviced.

Some instruments allow you to change the wavelength at which the lamp switch occurs. If you can restrict your absorbance measurements to the region of the spectrum accessible to a single lamp, you can avoid the lamp switching problem for now.

Are you talking about the dip at around 370 nm or disconnection of spectra at 300 nm? Probably it looks like the life time of your UV lamp is finished. You should try different samples in different solvents. If same happens in all then you should proceed to change the UV lamp.

Thank you very much Adam B Shapiro

Yes I think this is the problem of UV-lump. because we observe this problem with all the samples Raja Summe Ullah