What is the purpose of the Resolution Test Mixture supplied in the Chemical Solutions DIY Qualification Kits - FAQ
Date: 16-MARCH-2024 Last Updated: 5-JULY-2025
The Resolution Test Mixture (RTM) included in the "Do It Yourself", Chemical Solutions Qualification Kits serves a critical dual purpose in HPLC system evaluation:
1. Similar to a System Suitability Check
The RTM acts as a quick verification tool to ensure:- The mobile phase has been prepared correctly
- The HPLC system is functioning within expected parameters
- The test column is still viable and has not degraded significantly
2. Quantifying System Variance
By analyzing multiple peaks in the RTM, users can:- Graph total observed variance across peaks
- Deconvolute column variance from extra column variance (ECV) using linear regression
- Determine the intercept of the variance vs. retention time plot, which corresponds to the extra column variance
On many Agilent 1100/1200 systems, the typical extra column variance is around 120 µL² (equivalent to a standard deviation of ~11 µL). This is acceptable for standard 4.6 mm ID columns but may be too high for narrow-bore 2.1 mm columns, where dispersion effects are more pronounced.In contrast, older or poorly maintained systems may exhibit extra column variances as high as 800–900 µL², making them unsuitable for high-efficiency or small-format columns.
Why This Matters
Understanding and quantifying ECV helps you:- Select the right column dimensions for your system
- Optimize tubing and fittings to reduce dispersion
- Ensure your system is suitable for high-resolution or fast-gradient methods
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