Amperometric Detection of Carbohydrates with a Portable Silicone/Quartz Capillary Microchip by Designed Fracture Sampling

Science reports ∼4800 hits on capillary electrophoresis (CE) including 410 reviews. Because of the prominence of CE techniques in bioanalysis, we decided make them the focus of this review and selected 200 hundred papers representing advances in this field. The selected papers cover advances in CE theory, instrumentation, and methodologies that are specific to various analytes of biological origin or relevance. The group of analytes includes nucleic acids, proteins and peptides, carbohydrates, lipids, single cells, and bioparticles. In addition, we have included advances in the use of CE to define functional assays or to investigate biomolecular interactions. The use of microfabricated devices for CE analysis was not included because this is already covered in other review. Technique Developments Separation SchemesDetermining the velocity of the electroosmotic flow (EOF) and how it changes during an electrophoretic separation is still an important research topic. A simple method for EOF measurements using so-called thermal marks was reported (1). Here, a tungsten filament caused punctual heating at the capillary wall and caused a perturbation in the electrolyte concentration. A sequence of these "thermal marks" then migrated with the EOF until each mark reached and was detected by a conductivity detector. The feasibility of using thermal marks as internal EOF standards in different separation systems was thereby demonstrated.Isoelectric focusing separates amphoteric analytes such as proteins or peptides by the differences in their isoelectric points. Most of the reports on capillary isoelectric focusing (cIEF) describe an initial focusing phase after which the focused zones are mobilized and detected. A dynamic cIEF method for protein analysis was reported (2). This technique made it possible to control each protein's position and focused width by moving the pH gradient within the capillary through manipulation of the electric fields. An important advantage of this approach is the capability of collecting focused analytes from the central section, suggesting that there may be great potential for introducing selectively focused proteins to a second separation dimension such as LC or CE.Micellar electrokinetic capillary chromatography (MEKC) is typically incompatible with electrospray mass spectrometry (ESI-MS) because the nonvolatile surfactants in the micellar phase result in complicated adduct formation and loss of sensitivity during the electrospray process and because the presence of the organic solvent needed for electrospray may cause instability in the micellar phase. These drawbacks were overcome by using synthetic polymeric surfactants that can work as a pseudostationary phase and provide stable electrospray (3). The polymeric surfactant was made by polymerizing three amino acidderived (L-leucinol, L-isoleucinol, L-valinol) sulfated chiral surfactants. These polymeric

show abstract

“…Another approach used an ultranarrow sampling fracture formed on a quartz capillary held in place with molded PDMS (26). The 25-μm-i.d.…”

Section: Processes Prior To Cementioning

confidence: 99%

Capillary Electrophoresis in Bioanalysis

2008

View full text Add to dashboard Cite

show abstract

“…Even shorter length capillaries (1 cm and 3 cm) in combination with chemiluminescence detection (CLD) were used by Tsukagoshi et al [81]. Several other CE designs with short capillaries have been described with varying potential for portability [86,[103][104][105][106]. Fig.…”

Section: Capillarymentioning

confidence: 99%

Portable capillary-based (non-chip) capillary electrophoresis

Ryvolová

Preisler

Brabazon

et al. 2010

TrAC Trends in Analytical Chemistry

View full text Add to dashboard Cite

Miniaturized, portable instrumentation has been gaining popularity in all areas of analytical chemistry. Capillary electrophoresis (CE), due to its main strengths of high separation efficiency, relatively short analysis time and low consumption of chemicals, is a particularly suitable technique for use in portable analytical instrumentation. In line with the general trend in miniaturization in chemistry utilizing microfluidic chips, the main thrust of portable CE (P-CE) systems development is towards chip-based miniaturized CE. Despite this, capillary-based (non-chip) P-CE systems have certain unmatched advantages, especially in the relative simplicity of the regular cylindrical geometry of the CE capillary, maximal volume-to-surface ratio, no need to design and to fabricate a chip, the low costs of capillary compared to chip, and better performance with some detection techniques. This review presents an overview of the state of the art of P-CE and literature relevant to future developments. We pay particular attention to the development and the potential of miniaturization of functional parts for P-CE. These include components related to sample introduction, separation and detection, which are the key elements in P-CE design. The future of P-CE may be in relatively simple, rugged designs (e.g., using a short piece of capillary fixed to a chip-sized platform on which injection and detection parts can be mounted). Electrochemical detection is well suited for miniaturization, so is probably the most suitable detection technique for P-CE, but optical detection is gaining interest, especially due to miniaturized light sources (e.g., light-emitting diodes).

show abstract

“…The electrode was successively polished with 2000-mesh and 4000-mesh sandpapers until a mirror-like appearance was observed, followed with washing and sonication in water bath. The WE was then oxidized in an air-oven at 1001C for more than 4 h and stored in a desiccator before use [29]. This procedure could ensure the reproducibility of the copper microelectrodes preparation.…”

Section: Equipmentmentioning

confidence: 99%

“…Too small distance would cause large noise, while far distance produced band broadening. Then a Ag/AgCl reference electrode and a Pt wire as the auxiliary electrode were inserted to two sides of the DR due to the flexibility of PDMS matrix [29] to obtain an integrated three-electrode system for electrochemical detection (EC) of amino acids (Fig. 1A).…”

Section: Fabrication Of Amdmentioning

confidence: 99%

See 1 more Smart Citation

Highly resolved separation and sensitive amperometric detection of amino acids with an assembled microfluidic device

et al. 2009

Self Cite

View full text Add to dashboard Cite

An assembled microfluidic device (AMD) was constructed for highly resolved separation and sensitive amperometric detection of amino acids. In the AMD three polymer retainers were integrated with a quartz capillary and a copper microdisk electrode. A facile ultrasonic method was suggested for the preparation of sampling fracture on the capillary. The fracture led to separation efficiency up to 340,000 plates/m and improved greatly the sensitivity for amino acid detection in an 8 cm long quartz capillary. At a sampling voltage of 100 V for 2 s and a separation voltage of 1800 V (225 V/cm) within 300 s, the linear ranges of 12 amino acids determination at +0.8 V (versus Ag/AgCl) were from 12, 20, 17, 27, 31, 44, 25 and 45 to 750 microM for tryptophan, phenylalanine, methionine, valine, threonine, alanine, serine and glycin, and 4.6, 17, 16 and 49 microM to 1.0 mM for lysine, proline, leucine and tyrosine with the detection limit (S/N=3) down to 1.4 microM for lysine. The designed AMD could be successfully applied to analyze amino acids in beverage samples with recovery from 97.8 to 105.2%, indicating its advantages and potential analytical application in different fields.

show abstract

Amperometric Detection of Carbohydrates with a Portable Silicone/Quartz Capillary Microchip by Designed Fracture Sampling

Cited by 30 publications

References 37 publications

Capillary Electrophoresis in Bioanalysis

Capillary Electrophoresis in Bioanalysis

Portable capillary-based (non-chip) capillary electrophoresis

Highly resolved separation and sensitive amperometric detection of amino acids with an assembled microfluidic device

Contact Info

Product

Resources

About