Classical UV detectors based on a monochromator record 2D data as a chromatogram. These devices are called VWD or MWD. Nevertheless, 3D-like measurements can be done by scanning the wavelength range. VWD or MWD detectors cannot record 3D data over the whole analysis time but just in programmed time frames.
Devices based on DAD technology are able to record 3D data in addition to the 2D data over the whole analysis time.
3D data means that full UV spectra are measured and these spectra are plotted over the whole time. This is useful for unknown analytes or target compounds with different UV characteristics. Additionally, 2D chromatograms can be extracted from 3D-data at any wavelength.