How to use Special Values in User Columns in Clarity Chromatography Software

The Clarity Chromatography Data System (CDS), developed by DataApex, is a powerful tool for managing and processing chromatographic data. Among its advanced capabilities is the option to create custom calculations using user-defined columns in the Results Table.

This article explains how to utilize special values within these user-defined columns to perform dynamic and customized calculations — such as computing relative retention times or summed peak parameters.

By following this guide, laboratory analysts and chromatography professionals can optimize their data evaluation workflows directly within Clarity, without relying on external software.

Overview of Special Values in Clarity

In Clarity, special values are predefined functional operators that enable users to perform calculations using contextual data from the Results Table. These values can reference:

• All peaks in a column (e.g., sum)
• Specific positions (e.g., first, last)
• Individual compounds identified in the chromatogram

Special values are used within user-defined expressions, allowing for flexible mathematical or logical operations between chromatographic results.

Creating a User Column

Step 1: Open the Results Table

After performing a chromatographic run and generating results, navigate to the Results Table window within Clarity.

Step 2: Access the Add User Column Dialog

1. Right-click anywhere within the Results Table.
2. From the local context menu, select Add User Column.
3. This opens the Add User Column dialog, where you can define new calculated fields.

Utilizing Special Values

Example 1: Summing All Values in a Column

Using the special value sum, Clarity can automatically total all numeric entries within a selected column.

• Expression example: sum(area)
• Function: Adds all peak areas to calculate the total signal response.

Example 2: Selecting the First Peak Value

The special value first can extract data from the first chromatographic peak.

• Expression example: first(retention_time)
• Function: Returns the retention time of the first eluting peak in the Results Table.

Example 3: Calculating Relative Retention Time (RRT)

In this demonstration, a relative retention time is calculated based on a reference compound (e.g., Naphthalene).
This approach allows normalization of retention times across chromatograms.

Procedure:

1. In the Expression field, enter the formula: retention_time / retention_time(Nap)
2. Assign a suitable column title, such as “Relative Retention Time”.
3. Click OK to save and apply the custom user column.

*(“Nap” represents the reference compound.)

Once created, the new column appears automatically in the Results Table, performing the defined calculation across all peaks.

Data Storage and User Profiles

All user-defined columns and their calculated results are stored in the desktop file associated with the active user account. This ensures that each operator’s customized configurations, including formulas and results, remain accessible and secure for future sessions.

Practical Applications

User columns with special values can be used for:

• Automating peak-based quality control calculations
• Normalizing chromatographic parameters (RRT, RRF)
• Summing total areas or concentrations for grouped peaks
• Calculating ratios between target and reference compounds
• Creating compound-specific reports for validated methods

These features minimize manual data manipulation, reduce transcription errors, and streamline regulatory compliance workflows.

Discussion: Benefits of Using Special Values

Incorporating special values in Clarity offers several advantages:

• Efficiency: Eliminates the need for manual calculations or external spreadsheets.
• Accuracy: Reduces user error by automating formula execution.
• Flexibility: Supports both simple and complex mathematical relationships.
• Traceability: Ensures calculated data remain linked to chromatographic results within the same project environment.

By mastering this feature, analysts can enhance both analytical precision and workflow reproducibility.

Conclusion

The Add User Column function in Clarity CDS enables analysts to customize chromatographic data analysis with precision. By leveraging special values, such as sum, first, or specific compound references, users can generate real-time calculations — including relative retention times and aggregate peak metrics — directly in the Results Table.

This powerful capability not only streamlines data processing but also ensures compliance, traceability, and efficiency in analytical laboratories.