Mobile phase selection in HPLC Which statement best reflects what can be used as a mobile phase in high-performance liquid chromatography (HPLC)?

Introduction / Context:
In HPLC, the mobile phase is a liquid that transports analytes through the stationary phase. Proper solvent selection is critical for solubility, chromatographic retention, peak shape, detector compatibility, and safety.

Given Data / Assumptions:

• Common mobile phases include water, methanol, acetonitrile, buffers, and their mixtures.
• Analytes must dissolve to be injected without precipitation in the system.
• Solvent must be compatible with the stationary phase and detector (e.g., UV transparency for UV detection).

Concept / Approach:
The correct principle is that the mobile phase must be a liquid (or mixture) that dissolves the analyte and works with the column and detection method. Insoluble or poorly soluble systems will cause blockages, poor recovery, and unreliable chromatography.

Step-by-Step Solution:
Require adequate analyte solubility in the chosen solvent system.Ensure compatibility with bonded phase (e.g., avoid solvents that strip ligands) and equipment seals.Consider detector needs (e.g., low UV cutoff for UV detection).Select the option stating these conditions.

Verification / Alternative check:
Method validation often includes solubility screens and UV cutoff checks; successful runs confirm the practical solvent compatibility requirement.

Why Other Options Are Wrong:
Limited or zero solubility (options b and c) are incompatible with HPLC operation.“Any of the above” (option d) incorrectly implies insoluble systems are acceptable.

Common Pitfalls:
Choosing mobile phases with high UV absorbance for UV detection; ignoring buffer volatility for MS; exceeding pressure limits with viscous solvents.

Final Answer:
Any liquid (or liquid mixture) in which the analyte is sufficiently soluble and which is compatible with the column and detector.