Abstract: AIM: To study the chiral separation of NG-nitro-arginine enantiomers in biological samples by capillary electrochromatography (CEC).METHODS: The separation of D-NNA and L-NNA in plasma was achieved by chiral ligand exchange method via CEC.An aqueous eluent containing aspartame (2 mmol/L) sufficiently mixed with Cu²⁺ was used.The eluent was monitored at UV 280 nm.RESULTS: The retention times were 16 and 19 min for L-NNA and D-NNA, respectively.The standard curves of D-NNA and L-NNA ranged from 0.025 to 0.75 mmol/L (R² >0.98).The withinday precision of the quality control samples was 3.0 %for both L-NNA and D-NNA.The between-day precision was 3.1 % for L-NNA and 3.4 % for D-NNA, respectively.CONCLUSION: This method was established to determinate D L-NNA in biological samples with high resolution and efficiency.

Key words: N^G-nitro-arginine, chiral separation, ligand exchange, capillary electrochromatography, plasma