Overview

The HSQ™ Qualification Kit includes gradient testing procedures that evaluate the ability of an HPLC system to accurately proportion solvents and deliver programmed gradient compositions. These tests are performed using predefined mobile phase percentages incorporated into the qualification workbook calculations.

The standard gradient settings were selected to maximize the ability to detect pump proportioning errors and gradient inaccuracies across a wide range of instrument configurations.

Standard Gradient Compositions

The qualification workbook uses default mobile phase settings of:

• 100% / 0%
• 90% / 10%

for each solvent pair included in the evaluation.

Depending on the configuration of the HPLC system, testing may be performed using up to four solvent channels or solvent pairs.   These predefined values are incorporated into the qualification calculations and are used to assess gradient accuracy from detector response measurements.

Can Alternative Solvent Ratios Be Used?

Yes.

Alternative solvent compositions may be used when required by internal procedures or specific testing objectives.

Examples might include:

• 50% / 50%
• 80% / 20%
• 70% / 30%

However, users should understand that changing the solvent ratios may alter the sensitivity of the qualification test.

Why the 90/10 Composition Is Recommended

The 90% / 10% composition was selected because pump proportioning errors and gradient inaccuracies are often easier to detect at extreme solvent ratios.

Testing near the limits of gradient proportioning can make it easier to identify:

• Valve performance issues
• Mixing inaccuracies
• Solvent proportioning errors
• Gradient formation problems
• Pump calibration deviations

As a result, the standard qualification settings provide a more demanding assessment of gradient performance.

Impact of Using Different Percentages

When more moderate solvent ratios are used, such as 50% / 50%:

• Detector responses may become less sensitive to proportioning errors.
• Small gradient inaccuracies may be more difficult to identify.
• Overall test sensitivity may be reduced.

Although the system can still be evaluated, the qualification procedure may not challenge the instrument to the same extent as the recommended settings.

Qualification Workbook Considerations

The HSQ™ qualification workbook was designed around the standard solvent ratios included in the qualification procedure.

Following the recommended compositions helps ensure:

• Consistent qualification calculations
• Standardized testing conditions
• Reliable comparison of results
• Maximum sensitivity to gradient errors

For most users, the default values remain the preferred choice.

Best Practices

For routine gradient qualification testing:

• Use the standard 100/0 and 90/10 solvent compositions whenever possible.
• Follow the qualification workbook instructions as written.
• Reserve alternate solvent ratios for special circumstances or internal qualification requirements.
• Document any deviations from the standard procedure.

These practices help maintain consistency and simplify qualification recordkeeping.

Key Takeaways

• The HSQ™ Qualification Kit uses standard gradient compositions of 100/0 and 90/10.
• Alternative solvent ratios can be used when necessary.
• Extreme solvent ratios provide greater sensitivity to gradient inaccuracies.
• The qualification workbook is optimized for the recommended compositions.
• Using moderate solvent ratios may reduce the ability to detect subtle pump proportioning errors.
• Standard settings are recommended whenever possible for consistent qualification results.

For Chemical Solutions™ HSQ™ and PQ™ Qualification Kit Specifications, Qualification Resources, Product Images, and Ordering Information, view Chemical Solutions™ HSQ™ and PQ™ Qualification Kit Specifications, Qualification Resources, Product Images, and Ordering Information.