Derivatized vancomycin stationary phases for LC chiral separations

Area of Science:

• * Analytical Chemistry
• * Chromatography
• * Chiral Separations

Background:

• * Chiral stationary phases (CSPs) are crucial for separating enantiomers.
• * Vancomycin is a known chiral selector used in CSPs.
• * Modifying CSPs can enhance or alter their separation capabilities.

Purpose of the Study:

• * To synthesize and evaluate novel CSPs by derivatizing vancomycin with R- or S-(1-naphthylethyl) carbamate (NEC).
• * To compare the chromatographic performance of these new CSPs against a commercial underivatized vancomycin CSP.
• * To investigate the impact of NEC derivatization on enantioselectivity across different chromatographic modes.

Main Methods:

• * Synthesis of two CSPs by bonding R-NEC and S-NEC-derivatized vancomycin to silica gel.
• * Evaluation of CSPs using 60 enantiomeric pairs across normal-phase, reversed-phase, and polar aprotic organic modes.
• * Comparison of resolution and selectivity with a commercial underivatized vancomycin CSP.

Main Results:

• * NEC-derivatized CSPs resolved 43% of compounds not resolved by the native vancomycin CSP.
• * Enantiorecognition was lost for 12% of compounds upon NEC derivatization.
• * 45% of compounds were resolved by both native and NEC-derivatized CSPs, indicating complementary selectivity.

Conclusions:

• * NEC derivatization of vancomycin creates CSPs with altered polarity and potentially new interaction sites.
• * The modified CSPs offer complementary enantioselectivity to the native vancomycin CSP.
• * NEC derivatization can enhance chiral recognition for specific enantiomeric pairs, though it may reduce it for others.