Optimization of the separation and detection of the enantiomers of isoproterenol in microdialysis samples by cyclodextrin-modified capillary electrophoresis using electrochemical detection

Sensitive chiral analysis by capillary electrophoresisIn this review, an updated view of the different strategies used up to now to enhance the sensitivity of detection in chiral analysis by CE will be provided to the readers. With this aim, it will include a brief description of the fundamentals and most of the recent applications performed in sensitive chiral analysis by CE using offline and online sample treatment techniques (SPE, liquid-liquid extraction, microdialysis, etc.), on-column preconcentration techniques based on electrophoretic principles (ITP, stacking, and sweeping), and alternative detection systems (spectroscopic, spectrometric, and electrochemical) to the widely used UV-Vis absorption detection.

Section: Offline Sample Treatment Techniques For Sensitive Chiral Anamentioning

confidence: 99%

Sensitive chiral analysis by capillary electrophoresis

García-Ruiz

Marina

2006

“…It can be performed for either cationic or anionic analytes by "acid stacking" [ 12 ] or "base stacking" [ 13,14 ], respectively. The focus of this research involves the use of base stacking, where the electroosmotic flow (EOF) is reversed and the separation is performed with reverse polarity.…”

Section: Introductionmentioning

confidence: 99%

Enhanced pH‐mediated stacking of anions for CE incorporating a dynamic pH junction

Arnett

Lunte

2007

A technique has been developed to enhance analyte focusing for capillary electrophoresis for the analysis of physiological samples. High-ionic strength samples are titrated to low-ionic strength online using pH-mediated sample stacking in conjunction with a dynamic pH junction. This method concentrates analytes by reducing their electrophoretic mobility during field-amplification. Parameters responsible for enhanced focusing were investigated, and an enhanced pH-mediated stacking method was optimized for anionic nucleosides. The process results in ultra-narrow peak widths, for example, 0.28 s for thymidine with a 10-minute analysis time. Peak width and resolution with the enhanced stacking method were also compared to normal base stacking and electrokinetic injection. With this technique, mass-loading capacity can be increased without degradation in peak shape and resolution is dramatically improved.

“…Lin et al [15] employed CEEC for analysis of purine bases, ribonucleotides and ribonucleosides in plasma. Hadwiger et al [16] demonstrated that while quantitation of isoproterenol was not possible with CE-UV because of insufficient detection limits, a detection limit of 13 nM could be achieved using CEEC. In addition, detection limits for catechol standards have been reported to be in the range of 2-5 nM [17,18].…”

mentioning

confidence: 99%

Detection of a urinary biomaker for oxidative DNA damage 8-hydroxydeoxyguanosine by capillary electrophoresis with electrochemical detection

Weiss

Lunte

2000

Abstract8-Hydroxydeoxyguanosine (8-OHdG) is present in urine as a result of oxidative DNA damage associated with age-related diseases such as cancer. In this report a method is presented for the detection of 8-OHdG in human morning urine utilizing capillary electrophoresis with electrochemical detection (CEEC). The limit of detection for a aqueous standard of 8-OHdG is 50 nM (signal to noise ratio S/N = 3). A single solid-phase extraction (SPE) step with a C18 column is used for sample cleanup and 20-fold preconcentration of the urine before analysis by CEEC. Optimized conditions for analysis of extracted urine are E app = 0.5 V vs. Ag/AgCl with 20 mM sodium borate/20% MeOH v/v, pH 9, as the background electrolyte, and a separation voltage of 22 kV. The concentration of 8-OHdG varied from 6 to 86 nM with an average value of 42 ± 26.9 nM for four healthy female and four healthy male subjects between the ages of 23 and 43.