How to check the signal-to-noise ratio with OpenLab CDS (ver 2.x)

Document created by lily Employee on Sep 8, 2020Last modified by carlos_vargas on Oct 7, 2020
Version 8Show Document
  • View in full screen mode

Agilent Support Insights


This Information Applies To: Agilent OpenLab CDS (ver 2.x)



The following procedure shows how to check the signal-to-noise ratio in OpenLab CDS (ver 2.x).


Steps to Follow:


  • Use a processing method configuration that includes system suitability parameters feature. (see Figure 1)
Figure 1  System Suitability location in the processing method description


  • To be able to carry out the procedure as described, you need the privilege Processing Method > Edit system suitability parameters. Privileges are configured in the Control Panel. (see Figure 2)
    Figure 2   Edit system suitability parameters location

Edit the processing Method.

1. Optimize data integration.

Switch to "Home" tab, click "Processing Method" to bring in the "Processing Method" window. Set the desired integration parameters according to the chromatogram.


Figure 3

1. Processing method tab

2. Standard Integration Events

3. Global signal


2. Set system suitability parameters.

In the Processing Method window, select the System Suitability > Properties node. Then fill out the parameters in the page. The following is a detailed explanation of these parameters:

  • Signal-to-noise: choose All Peaks.
  • Noise Calculation: Select the required Noise calculation, Software supplies four options to calculate noise ASTM, 6SD, P2P, RMS.
  • 6 sigma or RMS method

The signal-to-noise is calculated using the formula:

Signal-to-noise = Height of the peak / Noise of closest range

  • Peak to peak or ASTM method

The signal-to-noise is calculated using the formula:

S/N = 2 H/h



Height of the peak corresponding to the component concerned in the chromatogram obtained with the prescribed reference solution.


Absolute value of the largest noise fluctuation from the baseline in a chromatogram obtained after injection or application of a blank and observed over a distance equal to 20 times the width at half-height of the peak in the chromatogram obtained with the prescribed reference solution, and situated equally around the place where this peak would be found.

According to the definition of the European Pharmacopoeia, signal-to-noise is calculated against a blank reference signal and a noise calculated over the time range that contains the peak the S/N ratio is being calculated for.

  • Noise range:

Automatic(On blank recommended for EP): the noise is calculated in the last blank run (sample type = Blank) which was acquired before the injection. The range is calculated at the retention time of the peak -10 and +10 times the half peak width on the corresponding signal.

Fixed: the noise is calculated in a fixed range of the current signal or the last blank signal

Relative from: Time region relative to the peak start or end, on the same signal or on a blank reference signal.

                                                                                        Figure 4  System Suitability  parameters


3. Reprocess the injections.


4. In the Injection Results window, click show column chooser on the left and choose columns S/N and Noise (The S/N column contains the signal-to-noise ratio as calculated with the chosen algorithm.), you could see the S/N and Noise results in the table. (see Figure 5)


Figure 5

1. Injection Results tab

2. Show column chooser

3. Noise column

4. S/N column



Learn more on how to effectively operate OpenLab CDS, please refer to the following:

Data Analysis Reference Guide User manual



Keywords: System Suitability, signal-to-noise ratio, signal to noise, S/N, EP, JP, USP, pharmacopeia, Noise range, OpenLab, CDS, Workstation, Workstation Plus



1 person found this helpful