Combination of large volume sample stacking and dynamic pH junction for on-line preconcentration of weak electrolytes by capillary electrophoresis in comparison with isotachophoretic techniques

Hořáková, Jana; Petr, Jan; Maier, Vítězslav; Znaleziona, Joanna; Staňová, Andrea Vojs; Marák, Jozef; Kaniansky, Dušan; Ševčı́k, Juraj

doi:10.1016/j.chroma.2007.01.075

Cited by 30 publications

(21 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A 4600-fold enhancement in sensitivity was obtained when compared with a typical CZE method, although a 2 h injection was required to achieve this. The same group researched another very similar dual strategy by the means of LVSS and dynamic pH junction to preconcentrate the previously described acids [40]. This time the preferred injection was hydrodynamic which resulted in LODs at 10 and 11 nM levels for benzoic and sorbic acids respectively, which is slightly higher than for the electrokinetic injection discussed in the previous study.…”

Section: Best Sensitivity Enhancements and Lodsmentioning

confidence: 93%

Online sample pre‐concentration via dynamic pH junction in capillary and microchip electrophoresis

Kazarian

Hilder

Breadmore

2011

J of Separation Science

View full text Add to dashboard Cite

Various analytical techniques have been developed over the years to analyse a large diversity of biomolecules with a constant push towards ultra-sensitive detection. CE is at the forefront of the most powerful analytical tools available to date when considering its superior efficiency and resolution; however, the technique suffers from poor sensitivity as a result of the short path length at the detection site and small injection volumes (typically <1% capillary length). One of the approaches to abate the inherent problem is to employ clever chemistry using sample focusing techniques whereby a large sample plug can be injected, preconcentrated and separated, producing excellent sensitivity and efficiency at the detector. This particular review will focus on the use of dynamic pH junction as a means of improving sensitivity in CE and focuses on the use of a change in analyte ionisation due to different pHs between the sample and electrolyte. The review provides a fundamental discussion of the mechanisms, buffer and sample conditions required to concentrate various analytes and a comprehensive list of published works in tabular format for easy identification of suitable conditions for new applications. The review further encompasses the use of dynamic pH junction in CE and its involvement in combination with other preconcentrations techniques to produce high sensitivity enhancements recorded between the years 1990-2010.

show abstract

Section: Best Sensitivity Enhancements and Lodsmentioning

confidence: 93%

Online sample pre‐concentration via dynamic pH junction in capillary and microchip electrophoresis

Kazarian

Hilder

Breadmore

2011

J of Separation Science

View full text Add to dashboard Cite

show abstract

“…Here are several examples: field-enhanced sample injection (FESI)1SWP ($million-fold increase in sensitivity) [215,216], FESI1tITP (3000-fold concentration) [217], SWP1DPJ (suitable for a mixture of neutral and weakly acidic/basic analytes) [218], large volume sample stacking (LVSS)1DPJ (preconcentration of weak electrolytes) [219], pH-mediated FESS1DPJ (sensitivity enhancement only for ionizable analytes) [220], tITP1DPJ (50-fold increase in sensitivity, nanomolar LODs) [221], LVSS1SWP (LODs up to 10 À10 mol/L) [122], a cation selective exhaustive injection1SWP (50-200 pg/mg LODs, 6-8 ppt LODs) [222,223]. In addition to these techniques, counter-flow gradient focusing [224] and electrocapture [225] can be considered as the techniques based on a combination of field-strength-and chemically induced changes in velocity offering new interesting possibilities in on-line sample preparation.…”

Section: Single-column Techniques (In-capillary)mentioning

confidence: 99%

Advanced CE for chiral analysis of drugs, metabolites, and biomarkers in biological samples

Mikuš

Maráková

2009

Electrophoresis

View full text Add to dashboard Cite

An analysis of recent trends indicates that CE can show real advantages over chromatographic methods in ultratrace enantioselective determination of biologically active compounds in complex biological matrices. It is due to high separation efficiency and many applicable in-capillary electromigration effects in CE (countercurrent migration, stacking effects) enhancing significantly (enantio)separability and enabling effective sample preparation (preconcentration, purification, analyte derivatization). Other possible on-line combinations of CE, such as column coupled CE-CE techniques and implementation of nonelectrophoretic techniques (extraction, membrane filtration, flow injection) into CE, offer additional approaches for highly effective sample preparation and separation. CE matured to a highly flexible and compatible technique enabling its hyphenation with powerful detection systems allowing extremely sensitive detection (e.g. LIF) and/or structural characterization of analytes (e.g. MS). Within the last decade, more as well as less conventional analytical on-line approaches have been effectively utilized in this field and their practical potentialities are demonstrated on many new application examples in this article. Here, three basic areas of (enantioselective) drug bioanalysis are highlighted and supported by a brief theoretical description of each individual approach in a compact review structure (to create integrated view on the topic), including (i) progressive enantioseparation approaches and new enantioselective agents, (ii) in-capillary sample preparation (preconcentration, purification, derivatization), and (iii) detection possibilities related to enhanced sensitivity and structural characterization.

show abstract

“…Another solution to improve the LOF is to integrate an on-line preconcentration process for sample analytes. Several groups have developed on-capillary preconcentration techniques, including field-amplified stacking [25], field-enhanced sample injection [26], dynamic pH junction stacking [27], sweeping [28], and high-salt stacking [29]. Sample preconcentration offers increased sensitivity, robust electrokinetic injection schemes, and the possibility to use detection modes that are less sensitive than LIF [25,30].…”

Section: H]-or [mentioning

confidence: 99%

A highly sensitive CE‐UV method with dynamic coating of silica‐fused capillaries for monitoring of nucleotide pyrophosphatase/phosphodiesterase reactions

et al. 2008

View full text Add to dashboard Cite

A new highly sensitive capillary electrophoresis (CE) method applying dynamic coating and on-line stacking for the monitoring of nucleotide pyrophosphatases/phosphodiesterases (NPPs) and the screening of inhibitors was developed. NPP1 and NPP3 are membrane glycoproteins that catalyze the hydrolysis nucleotides, e.g. convert adenosine 5'-triphosphate to adenosine 5'-monophosphate (AMP) and pyrophosphate. Enzymatic reactions were performed and directly subjected to CE analysis. Since the enzymatic activity was low, standard methods were insufficient. The detection of nanomolar AMP and other nucleotides could be achieved by field-enhanced sample injection and the addition of polybrene to the running buffer. The polycationic polymer caused a dynamic coating of the silica-fused capillary, resulting in a reversed electroosmotic flow. The nucleotides migrated in the direction of the electroosmotic flow, whereas the positively charged polybrene molecules moved in the opposite direction, resulting in a narrow sample zone over a long injection time. Using this on-line sensitivity enhancement technique, a more than 70-fold enrichment was achieved for AMP (limit of detection, 46 nM) along with a short migration time (5 min) without compromising separation efficiency and peak shape. The optimized CE conditions were as follows: fused-silica capillary (30 cm effective lengthx75 mum), electrokinetic injection for 60 s, 50 mM phosphate buffer pH 6.5, 0.002% polybrene, constant current of -60 microA, UV detection at 210 nm, uridine 5'-monophosphate as the internal standard. The new method was used to study enzyme kinetics and inhibitors. It opens an easy way to determine the activities of slowly metabolizing enzymes such as NPPs, which are of considerable interest as novel drug targets.

show abstract

Combination of large volume sample stacking and dynamic pH junction for on-line preconcentration of weak electrolytes by capillary electrophoresis in comparison with isotachophoretic techniques

Cited by 30 publications

References 50 publications

Online sample pre‐concentration via dynamic pH junction in capillary and microchip electrophoresis

Online sample pre‐concentration via dynamic pH junction in capillary and microchip electrophoresis

Advanced CE for chiral analysis of drugs, metabolites, and biomarkers in biological samples

A highly sensitive CE‐UV method with dynamic coating of silica‐fused capillaries for monitoring of nucleotide pyrophosphatase/phosphodiesterase reactions

Contact Info

Product

Resources

About