Electrochemical detection, with

Micellar gradient elution liquid chromatography with electrochemical detection with sodium dodecyl sulfate has been used to separate phenols [186]. 

Aromatic and sulfur-containing amino acids were separated by HPLC, and subjected to post-column UV irradiation before electrochemical detection with GCE vs AgCl/Ag electrodes. The analytes showed different behavior during lamp off and on periods. Thus, for example, tyrosine (46) and tryptophan (47) showed inherent electrochemical response at +0.80 V, but none at +0.60 V however, on turning on the UV lamp they showed sensitive response at both potentials126. 

C Fernandez, AJ Reviejo, LM Polo, JM Pingarron. HPLC-electrochemical detection with graphite-poly(tetrafluoroethylene) electrode. Determination of the fungicides thiram and disulfiram. Talanta 43 1341-1348, 1996. 

Rocuronium Column X-Terra RP-C18 Human plasma column (20 x 4.6 mm) Detector amperometric electrochemical detection with electrode potential 1.1 V Mobile phase n/a... 

Figure 8.9. Separation of four phenylurea herbicides using (a) on-line UV detection at 254 nm and (b) on-line electrochemical detection with 1.35 V oxidation potential. Peaks 1, metoxuran 2, diuron 3, linuron 4, neburon. (Reprinted from Ref. 20 with permission.)...

The compatibility of electrochemical detection with the various modes of liquid chromatography is limited. For all practical purposes, electrochemical detection is not suitable for use with normal phase adsorption or partition chromatography due to the solvents of low dielectric constant used as the mobile phase. On the other hand, reverse-phase adsorption and partition (including ion-exchange or ion-pairing systems) are highly com-... 

Atsushi, A., Matsue T., and Uchida, I. Multichannel electrochemical detection with microelectrode array in flowing streams. Anal. Chem. 1992, 64, 44—49. 

The determination of catecholamines requires a highly sensitive and selective assay procedure capable of measuring very low levels of catecholamines that may be present. In past years, a number of methods have been reported for measurement of catecholamines in both plasma and body tissues. A few of these papers have reported simultaneous measurement of more than two catecholamine analytes. One of them utilized Used UV for endpoint detection and the samples were chromatographed on a reversed-phase phenyl analytical column. The procedure was slow and cumbersome because ofdue to the use of a complicated liquid-liquid extraction and each chromatographic run lasted more than 25 min with a detection Umit of 5-10 ng on-column. Other sensitive HPLC methods reported in the literature use electrochemical detection with detection limits 12, 6, 12, 18, and 12 pg for noradrenaline, dopamine, serotonin, 5-hydroxyindoleace-tic acid, and homovanillic acid, respectively. The method used very a complicated mobile phase in terms of its composition while whilst the low pH of 3.1 used might jeopardize the chemical stability of the column. Analysis time was approximately 30 min. Recently reported HPLC methods utilize amperometric end-point detection. 

Dopamine was quantitated by high-performance liquid chromatography (HPLC) with electrochemical detection with a detection limit of approximately 5 fmol/sample. An HPLC pump (LKB, Pharmacia) was used in conjunction with an electrochemical detector (Antec, Leiden) working at 625 mV versus an Ag/AgCl reference electrode. The analytical column was a Supelco Supelcosil LC-18 Column (3 pm particle size). The mobile phase consisted of a mixture of 4.1 g/1 sodium acetate (Merck), 85 mg/1 octane sulphonic acid (Aldrich), 50 mg/1 EDTA (Merck), 1 mM tetramethylammonium chloride (ACROS), 8.5 % methanol (Labscan) and ultra pure water (pH=4.1 with glacial acetic acid). 

Dopamine was quantitated by high-performance liquid chromatography (HPLC) with electrochemical detection with a detection limit of approximately 5 fmol/sample. An HPLC... 

Electrochemical detection with ion-pairing adaptations of reversed-phase chromatography are the most common methodologies, and many techniques for measuring urinary catecholamines and metanephrines have been... 

Janecek, M. Quilliam, M.A. Bailey, M.R. North, D.H. Determination of erythromycin A by liquid chromatography and electrochemical detection, with application to salmon tissue. J.Chromatogr., 1993, 619, 63-69 [electrochemical detection fish tissue SPE column temp 40 LOD 100 ng/g]... 

Durgbanshi, A. and Kok, W. Th., Capillary electrophoresis and electrochemical detection with a conventional detector cell, J. Chromatogr., 798, 289-296, 1998. 

Xia FQ, Jin WR, Yin XF, Fang ZL (2005) Single-cell analysis by electrochemical detection with a microfluidic device. J Chromatogr A 1063 227-233... 

J.F. Clos and J.G. Dorsey, Enhanced Stability of Electrochemical Detection with Surfactant Containing Mobile Phases in LC and Flow-Injection Analysis, Anal. Lett., 23 2327 (1990). 

Electrochemical detection with a vitreous-carbon electrode at -1-1.0 V vs. Ag/AgCl... 

A.J.J. Debets, R. Van De Straat, W.H. Voogt, H. Vos, N.P.E. Vermeulen and R.W. Frei, Simultaneous determination of glutathione, glutathione disulfide, paracetamol and its sulfur containing metabolites by HPLC with electrochemical detection with on-line generated bromine, J. Pharm. Biomed. Anal., 1988, 6, 329-336. 

In contrast to aromatic moieties, absence of w-resonance for aliphatic compounds results in very low oxidation rates even though the reactions may be favored thermodynamically. StabiUzation of free-radical products from aliphatic compounds can be achieved alternatively via their adsorption to the surface of noble metal electrodes. Unfortunately, adsorption of organic molecules and free radicals also has the consequence of fouling of the electrode and loss of its activity [57]. The historical perspective of nonreactivity for ahphatic compounds at noble metal electrodes can be attributed to surface fouling as a result of high, but transient, catalytic activity. An alternative approach is to combine electrochemical detection with on-hne cleaning. Hence, in order to maintain uniform and reproducible electrode activity at noble metal electrodes for polar aliphatic compounds. 

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