Role of counter-ions in background electrolyte for the analysis of cationgenic weak electrolytes and amino acids in neutral aqueous solutions by capillary electrophoresis with electrokinetic injection

• Published in: Journal of Chromatography A Vol. 1326; pp. 130 - 133
• Main Authors: Hattori, Takanari, Fukushi, Keiichi, Hirokawa, Takeshi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 24.01.2014; Elsevier
• Subjects: Amino acid; Amino acids; Amino Acids - analysis; Analytical chemistry; Aqueous solutions; Biological and medical sciences; Capillarity; Capillary electrophoresis; Cationgenic weak electrolyte; Chemistry; Chromatographic methods and physical methods associated with chromatography; Computer Simulation; Counter-ion; Creatinine; Creatinine - urine; Electrokinetic injection; Electrokinetics; Electrolytes; Electrolytes - analysis; Electrophoresis; Electrophoresis, Capillary - methods; Exact sciences and technology; histidine; Histidine - urine; Humans; Hydrogen-Ion Concentration; Investigative techniques, diagnostic techniques (general aspects); Ions; Male; Medical sciences; Migration; Miscellaneous. Technology; Other chromatographic methods; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Solutions; urine; Water; Amino acid; Cationgenic weak electrolyte; Counter-ion; Electrokinetic injection; Capillary electrophoresis; Creatinine; Human; Urine; Biological fluid; Chemical analysis; Zone electrophoresis; Healthy subject; Theoretical study; Experimental study; Mobile phase; α-Aminoacid; Ultraviolet detector; Histidine; Aqueous medium; Clinical biology; Counter ion; Numerical simulation
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2013.12.013

•Counter-ions boosted electrokinetic injection of cationgenic weak electrolytes and amino acids.•The counter-ions changed the sample pH to fulfill the electroneutrality requirement.•The pH change in the sample vial increased the analyte mobility.•The effectiveness of the method was confirmed theoretically and experimentally.•The proposed method determined creatinine and l-histidine in a urine sensitively. We elucidated theoretically and experimentally that counter-ions in background electrolyte (BGE) play a role of booster for electrokinetic injection (EKI) for the determination of cationgenic weak electrolytes and amino acids in neutral aqueous solutions using capillary electrophoresis (CE). The pH change in the sample solution caused by the migration of counter-ions resulted in the increase of analyte mobility and hence the increase of the amount of analyte injected into the capillary. This type of EKI was named as counter-ion boosted EKI. Using the counter-ion boosted EKI-capillary zone electrophoresis (CZE), the limit of detections (LODs, S/N=3) for creatinine (4.8nM) and l-histidine (9.0nM) were lowest ever achieved by CE with UV detection. The RSDs (n=3) of the migration time for creatinine and l-histidine were obtained as 0.35% and 0.34%, for peak areas of 13% and 12%, and for peak heights of 12% and 8.5%, respectively. The concentrations of creatinine and l-histidine in a urine sample obtained by the proposed method were within those reported with a good recovery.