Location:

Peak Tracking and Spectra Library Screening tab pages/Report Variable (Peak Table)

Type:

Selection

Dimension:

-

Value Range:

Off; 1st derivative; 2nd derivative

Default:

Off

Related Parameters:

Additional parameters for comparing spectra:

Check Extrema

Match Criterion

Maximum/Minimum Wavelength

Relative Maximum Deviation

Threshold

Description:

Comparison of two or more spectra with each other can be performed in three different ways (comparison functions):

• Based on the curve shape of the spectrum itself

• Based on the curve shape of the first derivative of the spectrum

• Based on the curve shape of the second derivative of the spectrum

Function:

Comparing the curve shape of the first or second derivative of the spectrum is more characteristic (shoulders become extremes). However, the Signal-to-Noise Ratio decreases considerably. Depending on the comparison function different Threshold values are useful.

 Note:

Differentiating once or twice can lead to well matching hits, although the absorption heights of the original spectra differ significantly.