Capacitively coupled contactless

Other electrode configurations, such as the radial arrangement consisting of four thin wires placed perpendicularly around the circumference of the separation capillary column, have found less application due to more complicated construction and restriction in space and diameter of the separation capillary [56]. Due to its low cost, robustness, minimal maintenance demands, possibility to be freely moved along the capillary [57], or combined with either UV-absorbance [58] or fluorescence [59] detection, the capacitively coupled contactless conductivity detector has recently gained wide acceptance not only for the determination of inorganic ions but also for biomolecules and organic ions, as it has been recently comprehensively reviewed by Kuban and Hauser [1]. 

J.G.A. Brito-Neto, J.A.F. da Silva, L. Blanes and C.L. do Lago, Understanding capacitively coupled contactless conductivity detection in capillary and microchip electrophoresis. Part 1. Fundamentals, Electroanalysis, 17 (2005) 1198-1206. 

P. Kuban and P.C. Hauser, Effects of the cell geometry and operating parameters on the performance of an external contactless conductivity detector for microchip electrophoresis, Lab Chip, 5 (2005) 407-415. J.G.A. Brito-Neto, J.A.F. da Silva, L. Blanes and C.L. do Lago, Understanding capacitively coupled contactless conductivity detection in capillary and microchip electrophoresis. Part 2. Peak shape, stray capacitance, noise, and actual electronics, Electroanalysis, 17 (2005) 1207-1214. 

A four-electrode capacitively coupled (contactless) detector has been integrated on a Pyrex glass chip for detection of peptides (1 mM) and cations (5 mM K+, Na+, Li+). The A1 electrode (500 nm Al/100 nm Ti) was deposited in a 600-nm-deep trench and was covered with a thin dielectric layer (30-nm SiC). The other parts of the channel were covered and insulated with Si3 N4 (160 nm). To avoid gas bubble formation after dielectric breakdown, the electric field for separation was limited to 50 V/cm [145]. This four-electrode configuration allows for sensitive detection at different background conductivities without the need of adjusting the measurement frequency [328]. 

Tanyanyiwa, J., Hauser, P.C., High-voltage capacitively coupled contactless conductivity detection for microchip capillary electrophoresis. Anal. Chem. 2002, 74(24), 6378-6382. 

Other applications of CE to analyze food additives include the determination of vitamin C and preservatives (benzoate and sorbate) by both conventional CE and microchip electrophoresis with capacitively coupled contactless conductivity detection. The separation was optimized by adjusting the pH value of the buffer and the use of hydroxypropyl- -CD (HP- -CD) and CTAB as additives. For conventional CE, optimal separation conditions were achieved in a histidine/tartrate buffer at pH 6.5, containing 0.025% HP-f)-CD and 0.25 mM CTAB with a LOD ranging from 0.5 to 3 mg/L, whereas a histidine/tartrate buffer with 0.06% HP-fl-CD and 0.25 mM CTAB gave a LOD ranging from 3 to 10 mg/mL. By using a microchip electrophoresis format, a considerable reduction of analysis time was accomplished. ... 

Law, W. S., Kuba, R, Zhao, J. H., Li, S. F. Y., and Hauser, P. C., Determination of vitamin C and preservatives in beverages by conventional capillary electrophoresis and microchip electrophoresis with capacitively coupled contactless conductivity detection. Electrophoresis, 26, 4648, 2005. 

A. J. Zemann, Capacitively coupled contactless conductivity detection in capillary electrophoresis. Electrophoresis 24, 2125, 2003. 

Coupling of FIA with GD is the most frequent. For example for ammonium determination several FIA—GD systems have been developed. Different detection methods coupled with GD—FIA system have been compared elsewhere [69]. Other examples are an FIA—GD system exploiting conductometric detection for Kjeldahl-produced ammonia [70], an FIA—GD system [71] applied to clinical blood samples using a bulk acoustic wave impedance sensor, a GD—FIA system using a capacitively coupled contactless conductivity detection (C4D) [72] and a GD—FIA with conductometric detection to monitor the ammonium content in open ocean seawater samples [73]. 

HR. Braz, D.T. Ito, J.AR. da Silva, C.L. do Lago, J.J. Pedrotti, Trace levels determination of ammonium by flow injection analysis using gas-diffusion and capacitively coupled contactless conductivity detection. Electroanalysis 23 (2011) 2594-2600. 

Capacitive coupling contactless conductivity detectors (C4D) which avoid contact with the solutions using high frequencies (>1 MHz) have gained popularity due to their applications in capillary electrophoresis and ionic chromatography [20,21,29,30]. These have also been coupled to flow... 

K. Sereenonchai, S. Teerasong, S. Chan-Eam, P. Saetear, N. Choengchan, K. Uraisin, N. Amomthammarong, S. Motomizu, D. Nacapricha, A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection, Talanta 81 (2010) 1040-1044. 

Kuban, P. and Hauser, PC. (2008) A review of the recent achievements in capacitively coupled contactless conductivity detection. Anal. Chim. Acta, 607, 15-29. 

CE with capacitively coupled contactless was used for the simple, rapid, and simultaneous determination of aspartame, cyclamate, saccharin, and acesulfame-K in commercial samples of soft drinks and tabletop sweetener formulations [37]. A buffer solution containing 100 mM tris(hydroxymethyl)aminomethane and 10 mM histidine was used as BGE. A complete separation of the analytes could be attained in less than 6 min. The detection limit was considered to be better than those usually obtained by CE with photometric detection. Recoveries ranging from 94% to 108% were obtained for samples spiked with standard solutions of the sweeteners. 

Bergamoa, A.B., Silvaa, J. A.F and Jesusa, D.P. (2011) Simultaneous determination of aspartame, cyclamate, saccharin and acesulfame-K in soft drinks and tabletop sweetener formulations by capillary electrophoresis with capacitively coupled contactless conductivity detection. Food Chem., 124, 1714-1717. 

Elbashir, A.A. and Aboul-Enein, H.Y. (2012) Recent advances in applications of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) an update. Biomed. Chromatogr., 26, 990-1000. 

Mori, M., Kaseda, M., Yamamoto, T., Yamada, S., and Itabashi, H. (2012) Capillary ion electrophoresis-capacitively coupled contactless conductivity detection of inorganic cations in human saliva on a polyvinyl alcohol-coated capillary. Anal. Bioanal. Chem., 402 (7), 2425-2430. 

Gimenes, D. T., M. C. Marra, R. A. A. Munoz, L. Angnes, and E. M. Richter. 2014. Determination of propranolol and hydrochlorothiazide by batch injection analysis with amperometric detection and capillary electrophoresis with capacitively coupled contactless conductivity detection. Anal. Methods 6(10) 3261-3267. 

FIGURE 24.7 Sequential injection analysis-capillary electrophoresis manifold with contactless conductivity detection (SIA-CE-C D). C D capacitively coupled contactless conductivity detector DW deionized water ES electrolyte solution GI grounded interface HC holding coil HV high-voltage power supply ND needle valve S sample SC separation capillary SI syringe SLl 1 M NaOH SL2 1 M HCl SP syringe pump SS safety switch SV selection valve VI and V2 solenoid valves W waste. 

Ding YS, Rogers K (2010) Determination of haloacetic acids in water using solid-phase extraction/microchip capillary electrophoresis with capacitively coupled contactless conductivity detection. Electrophoresis 31 2 2-2607... 

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