Reporting Signal-to-Noise in OpenLab ChemStation

Answer

This Information Applies To: Agilent OpenLab ChemStation

Content 

The following procedure shows how to check the signal-to-noise ratio in Agilent OpenLab ChemStation and report the signal-to-noise ratio in classic and intelligent reports.

Background

Agilent OpenLab ChemStation has the following options to calculate the noise for reporting the signal-to-noise ratio;

• 6 Sigma: Noise is calculated using six times the standard deviation of the linear regression (6 sigma).
• USP (according to the definition of the United States Pharmacopoeia): Noise is calculated using the peak-to-peak formula.
• EP (according to the definition of the European Pharmacopoeia): Noise is calculated using the peak-to-peak formula. The data for the noise calculation is taken from a blank signal.

See the article Signal-to-Noise Calculation in OpenLab ChemStation for more details.

Steps to Follow

Setting the noise ranges

1. Launch an online or offline instrument in OpenLab ChemStation and select the Data Analysis view.

2. Load the selected signal in the data file and integrate analytical peaks on the chromatogram.

3. To report the signal-to-noise ratio, you first need to define specific time intervals of the noise range to calculate the result.
   From the main menu, click Report > System Suitability > Edit Noise Ranges (Figure 1)

   
   
   Figure 1. Edit Noise Ranges Function on Report Menu
   
   

4. You will see the Edit Noise Ranges dialog box (Figure 2) that lets you specify up to seven retention-time ranges for noise determination. The noise results are presented for each signal in a separate table. In addition, the signal-to-noise ratio is calculated for each integrated peak in each signal.
   To define specific time intervals for the noise range in the table, you should select the time interval of baseline before your analytical peaks. If you defined multiple time intervals, the interval closest to the peak will be used.

   
   
   Figure 2. Edit Noise Ranges dialog box
   
   

To report the signal-to-noise ratio in Classic and Intelligent Reports.

1. Click Report > Specify Report then under the Report Settings tab, check Use Classic Reporting (Figure 3, step 2) or Use Intelligent Reporting (Figure 4, step 2).

   For classic reporting, select Performance+Noise under the Report Style drop down menu (Figure 3, step 3), then click OK.

   For Intelligent reporting, click Browse and select Performance+Noise from the report template drop down list (Figure 4, step 3), then click OK

   
   
   Figure 3. Select the Performance+Noise report style of Classic Reporting.
   
   

   
   
   Figure 4. Select the Performance+Noise report template of Intelligent Reporting.
   
   

2. Save the Data Analysis method.

3. From the main menu, click Report >Print Report.

To add a column displaying the S/N ratio (6 Sigma, USP or EP) on your Intelligent Report.

1. From the navigation pane, click Report Layout then click the Report Templates tab and open the navigation pane to select your report style (.rdl). Click Edit Report Template (Figure 5)

   
   
   Figure 5. Navigate to the Edit Report Template working area
   1. Report Layout view, 2. Report Template Files, 3. Edit Report Template tap
   
   

2. Right click a column of the result table where you need to add the S/N ratio. Then from the contextual menu, click Insert Column To Right or Insert Column To Left > Peak > Signal To Noise EP, Signal To Noise USP or Signal To Noise 6 Sigma. (Figure 6)

   
   
   Figure 6. Inserting a new column
   1. Insert Column Functions, 2. Peak Detail
   
   

3. Save or Save as the new report template(.rdl), then go to Report Preview to review the results (Figure 7)

   
   
   Figure 7. Preview the results on the Intelligent Reporting
   
   

Learn how to effectively operate your Agilent OpenLab ChemStation: HPLC-OLCS-2130e - Improving and Reporting Signal-to-Noise Ratio in OpenLab CDS ChemStation e-learning course available from Agilent education