Mobile Phase pH (8-8.5):

• Silica Integrity: Most HPLC columns use silica-based stationary phases. At high pH (above 8.5), silica starts to dissolve, which can damage the column and shorten its lifespan.
• Analyte Ionization: Many analytes are organic acids or bases. In the desired pH range (8-8.5), they are mostly neutral, leading to optimal interactions with the stationary phase for separation. Highly acidic or basic conditions can cause excessive ionization, affecting retention time and peak shapes.
• Buffer Capacity: A pH of 8-8.5 is a good compromise for using common buffer systems that maintain consistent pH throughout the chromatography run, even with slight variations in mobile phase composition.

Internal Standard and Derivatization (HPLC vs GC/MS):

In your case, the focus might be on simply separating the analyte based on its properties, without quantification or needing to improve detection sensitivity. This would explain why an internal standard and derivatization might not be necessary for this particular HPLC analysis.

• Internal Standard: An internal standard is used for precise quantification by comparing the analyte peak area to the internal standard peak area. If quantification isn’t a requirement, an internal standard isn’t needed.
• Derivatization: Derivatization is often used in GC/MS to improve the volatility, thermal stability, or detection sensitivity of analytes. HPLC analysis might not require derivatization if the analyte has good solubility in the mobile phase and has a chromophore (light-absorbing group) for detection.

Referencing Specifics:

While this general information can be helpful, consulting the Sadeghipour 1996 paper and the manufacturer’s guidelines for the column would provide more specific details relevant to your experiment. These resources might mention the optimal pH range for the specific stationary phase and analytes, as well as if there are any exceptions to using an internal standard or derivatization for your particular case.