Optimizing enantioseparation of phenylthiohydantoin amino acids with polymerized sodium N-undecanoyl L-valinate in chiral electrokinetic chromatography

Chiral separation of phenylthiohydantoin (PTH)-amino acid derivatives by electrokinetic chromatography (EKC) using poly(sodium N-undecanoyl L-valinate) (poly(L-SUV)) was investigated. Seven PTH-DL-amino acids (alanine, valine, norvaline, norleucine, methionine, serine, and tryptophan) were separated and each enantiomeric pair was reserved. Chiral separation was also achieved for (+/-)-5-(p-hydroxyphenyl)-5-phenylhydantoin. Sodium dodecyl sulfate was added to the EKC buffer to improve peak shapes and enantioselectivity. Addition of methanol and urea as organic modifiers were also investigated under slightly acidic buffer conditions, but no improvement in chiral selectivity was observed. Comparisons were made between poly(sodium N-undecanoyl L-norvalinate) (poly (L-SUNV)) and poly(L-SW) to determine how changing the amino acid head group affects analyte-micelle complexes involved in chiral recognition.