Wavelength Switching

Usually, samples contain different substances with different UV spectra and different absorption maxima. Wavelength switching allows the detection of individual peaks at their optimum wavelength. Wavelength switching changes the wavelength of the respective measurement when the solvent composition changes, resulting in a composite chromatogram of the largest absorbance for each substance. The switching should occur so long before the retention time of the respective peak that the entire peak is detected at one wavelength.

Wavelength switching also allows the simultaneous analysis of substances with strongly differing absorption maxima, and little or no absorption at the wavelength of the other maximum.

Wavelength switching is program-controlled; that is, the switch time at which the wavelength of a specific channel is changed is entered in a control Program. The switch time and wavelength can be generated automatically by extracting the Optimum Integration Path from an opened 3D Field (Extract: Opt.Int.Path to Clipboard).

 Tip:

Wavelength switching is also possible with fluorescence detectors. Usually, the excitation wavelength should be changed at exactly the same time as the detection wavelength.

For information about how to perform wavelength switching, refer to Practical Tips for Device Control  Switching the Wavelength.