Open tubular capillary electrochromatography of underivatized amino acids using Rh(III) tetrakis(phenoxyphenyl)porphyrinate as wall modifier.
The separation of 17 "common" underivatized amino acids was attempted by open tubular capillary electrochromatography (OT-CEC) in fused-silica capillaries coated with Rh(III) tetrakis(phenoxyphenyl)porphyrinate (Rh(III)TPP(m-OPh)4OAc) using sodium phosphate and Tris-phosphate buffers as background electrolytes (BGEs). The OT-CEC separation of amino acids was compared with that obtained by capillary zone electrophoresis in bare fused-silica capillaries using the same BGEs. The amino acids were not derivatized and the UV-absorption detection was set at 200 nm. Depending on the experimental conditions at least 15 amino acids were separated. The best separations were obtained in a Rh(III)TPP(m-OPh)4OAc-coated capillary in 50 mM Tris-100 mM phosphate buffer at pH 2.25. Separation of the critical triplet Val-Ile-Leu was always at least indicated being better at higher BGE concentrations. Regarding the sensitivity of the method, lower concentration limits of detection (LODs) in the coated capillary were obtained for Thr, Gly, Tyr, and Val; the other amino acids exhibited lower LODs in the uncoated capillary. The separation of acidic amino acids was not achieved.
Charvátová
Jana
J
Institute of Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic.
Deyl
Zdenek
Z
Kasika
Václav
V
Král
Vladimír
V
D000596:Amino Acids / Q000302:isolation & purification*; D019075:Electrophoresis, Capillary / Q000379:methods*; D009942:Organometallic Compounds / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
D000596:Amino Acids; D009942:Organometallic Compounds; D011166:Porphyrins; C478759:acetatotetrakis((3-phenoxyphenyl)porphyrinato)rhenium(III)