Determinaltion of histidine urocanic acid isomers in the human skin by high-performance capillary electrophoresis

摘要

Histidine was baseline separatedform histamine, 1-methylhistamine and cis-and trans-urocanic acid using highperformance capillary electrophoresis(HPCE) on a fused-silica column(50 cmX75#mu#m) with 0.05 M NaH_2PO_4 buffer, pH5.0 , and 12 kV. The detection limit of histiine, trans-and cis-urocanic acid was 10~(-6) M at a wavelength of 214 nm. The detection limit of the urocanic acid isomers was sligtly enhanced to 5.10~(-7) M. At 267 nm. The transformation of the trasns-urocanic acid standard in vitro into the cis-isomer was dependent on the time f exposure and the energy of the light source. UVB light induced a significantly faster conversion than UVA lights. The HPCE ethod was used for the characterization and measurement of histidine and urocadnic acid in human skin eluates. The concentrations of histidine, trans-or cis-urocanic acid in ethanol washes from the skin of healthy, non-allergic volunteers were 2.22+-0.40 centre dot 10~(-5), 0.96+-0.26 centre dot 10~(-5) and 1.04+-0.30 centre dot 10~(-5) M, respectively, (mea+-SEM, n=8). The results obtained by HPCE Correlated well with data obtained by HPLC . Correlation coefficients of r~2=0.981, r~2=0.814 and r~2=0.956 were found for histidine, trans and cis-urocanic acid, respectively