Low-level chemiluminescence of N-β-alanyl-L-histidine (L-carnosine)

Oxidized N‐β‐Ala‐L‐His (L‐carnosine) emitted low‐level CL. The CL specificity was shown by experiments with L‐carnosine from six separate vendors, several L‐carnosine‐like compounds, and nine different oxidizers. Purity of L‐carnosine samples was analysed by RP–HPLC–MS, 1H‐NMR, MALDI–TOF–MS and ESI–MS. L‐Carnosine CL magnitude varied with source; consequently, detection sensitivity was 5–100 nmol. CL of L‐anserine (N‐β‐Ala‐1‐methyl‐L‐His) was equal to or less than L‐carnosine, depending upon oxidizer. H5IO6 (2 mmol/L) in 11 mmol/L NaOH or 20 mmol/L K3Fe(CN)6 + 10 mmol/L H2O2 in 100 mmol/L NaOH were oxidizers of choice. Scavengers of ·OH− radical quenched CL. Kinetic studies revealed a bi‐phasic CL comprising a short‐lived (