Online acid barrage stacking anti-salt injection for capillary electrophoresis of 9-fluorenylmethylchloroformate-derivatized amino acids in high ionic strength solutions by UV detection.
An acid barrage stacking (ABS) method has been shown to be feasible for online anti-salt injection in CE of 9-fluorenylmethyl chloroformate (FMOC)-labeled amino acids (AAs) detected by common UV absorption. The operation was performed on normal polar CE by sucking in an extra plug of acid following a sample zone, serving as a selective acid barrage to block the backward migration of weak anionic analytes due to a sudden mobility reduction via acid-base reaction which does not affect strong co-ions such as Cl(-) to penetrate the barrage freely. By CE-UV of FMOC-AAs in various NaCl solutions, the effectiveness of ABS was firmly validated, able to stand up to 500 mM NaCl and to stack analytes by 10(3)-fold calculated from the UV detection limits, that is 0.01 microM for ABS and 10 microM for non-stacking injection. The method was also validated by determining trace Glu and Asp in real samples of rat brain microdialysate, rat serum and human saliva. The intraday RSDs were 0.33-4.9% for migration time and 1.8-9.6% for peak area. The recoveries measured by spiking technique were 82-115% for Glu and 86-116% for Asp. Working equations were obtained by plotting peak height vs. concentration at 0.1-50 microM, with correlation coefficients of >0.999. The contents of Glu and Asp were thus found at 0.26-0.83 microM and 0.24-0.64 microM respectively, in rat brain microdialyste; 37-40 microM and 8.4-10 microM, respectively, in rat serum; and 3.5-5.8 microM and 1.0-4.1 microM, respectively in human saliva. They were consistent with the data from other methods.
Han
Yanli
Y
Beijing National Laboratory of Molecular Sciences, Laboratory of Analytical Chemistry for Life Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing , P R China.
Zuo
Min
M
Qi
Li
L
Liu
Kun
K
Mao
Lanqun
L
Chen
Yi
Y
D000596:Amino Acids / Q000032:analysis* / Q000097:blood; D000818:Animals; D001923:Brain Chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D017022:Flow Injection Analysis; D005449:Fluorenes / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009862:Online Systems; D009994:Osmolar Concentration; D051381:Rats; D012463:Saliva / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet
C411453:2,7-di-tert-butyl-9-fluorenylmethoxycarbonyl chloride; D000596:Amino Acids; D005449:Fluorenes; D012996:Solutions; D012965:Sodium Chloride; C054007:1-(9-fluorenyl)methyl chloroformate