June 11, 2015, 715004754 Rev. A
Page 58
4.2.1 Solvent quality
Use spectral-grade or HPLC-grade solvents to better achieve these goals:
• Reproducible results
• Minimal instrument maintenance
• Minimal optical interference
A dirty or impure solvent can cause these problems:
• Baseline noise and drift
• Plugged columns
• Blockages in the fluid path
4.2.2 Preparation checklist
The following solvent preparation guidelines help to ensure stable baselines and good
resolution:
• Filter solvents with a 0.22 µm filter.
• Degas the solvent.
• Stir the solvent.
• Protect solvents from drafts and shock.
4.2.3 Water
Use water only from a high-quality water purification system. If the water system
does not provide filtered water, filter it through a 0.22 µm membrane filter before use.
4.2.4 Buffers
When you use buffers, dissolve salts first, adjust the pH, and then filter to remove
undissolved material.
4.2.5 Tetrahydrofuran (THF)
When you use unstabilized THF, ensure that your solvent is fresh. Previously opened
bottles of THF contain peroxide contaminants, which cause baseline drift.
4.2.6 Refractive indices of common solvents
The following table lists the refractive indices for some common chromatographic
solvents. Consulting this table, verify that the solvent you intend to use for your
analysis has an RI significantly different from the sample components.
Warning: THF contaminants (peroxides) can explode when desiccated or
concentrated.
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