Dopamine electrochemical determination

Biochemical analyses of 6-OHDA-injected animals revealed a 93 percent depletion of dopamine. The tissue was assayed using electrochemical detection following separation by high-pressure liquid chromatography (Felice et al. 1978). recorded as ng/mg protein in the nucleus accumbens and compared to control rats with sham lesions (sham=65.5 4.4, lesion=4.9 1.5 t(39)=23.4). A lesion was defined as complete if 75 percent or more of the dopamine was determined to be depleted from the nucleus accumbens compared to mean sham group values. 

Domenech, A., Garcia, H., Domenech, M.T., and Galletero, M.S. 2002b. 2,4,6-Triphenylpyrylium ion encapsulated into zeolite Y as a selective electrode for the electrochemical determination of dopamine in the presence of ascorbic acid. Analytical Chemistry 74, 562-569. 

A.I. Gopalan, K.P. Lee, K.M. Manesh, P. Santhosh, J.H. Kim, and J.S. Kang, Electrochemical determination of dopamine and ascorbic acid at a novel gold nanoparticles distributed poly (4-aminothiophenol) modified electrode, Talanta, 71,1774—1781 (2007). 

A semipermeable membrane can also be obtained by electrochemical co-polymerization of two monomers. In such a case, one of the components may provide the charge-selective group while the other one controls the permeation rate for the neutrals. In this way some size discrimination of interfering species can be obtained. Application of the electrochemically synthesized composite membranes based on the co-polymerization of 4-hydroxybenzene sulphonic acid and 2-allylphenol for dopamine (DA) determination in a phosphate buffer solution at pH = 7, in the presence of interfering ascorbic acid (AA), illustrates this possibility [28]. 

X., Shi, J., and Hao, A. (2014) Reduced graphene oxide-carbon dots composite as an enhanced material for electrochemical determination of dopamine. Electrochim. Acta, 130, 805 -809. 

F. Gonon, R. Cespuglio, J.-L. Ponchon, M. Buda, M. Jouvet, R.N. Adams and J.-F. Pujol, in vivo continuous electrochemical determination of dopamine... 

In recent years, polyirnide-modified electrodes are widely used in the field of sensor and biosensor. Among the electroactive species, dopamine (DA) has been of interest to neuroscientists and chemists. A loss of DA containing neurons may result in some serious diseases such as Parkinsonism. Therefore, the determination of the concentration of this neurochemical is important. Dopamine in central nervous system coexists with ascorbic acid, whose oxidation peak potential is close to that of dopamine. Therefore, a significant problem faced in electrochemically determination of dopamine is the presence of electroactive ascorbic acid, which reduces the selectivity and sensitivity [28-30]. 

Hu WN, Sun DM, Ma W. Simultaneous electrochemical determination of dopamine and epinephrine with a silver-doped polyjl-gjutamic add) modified electrode. Chem Anal 2008 53 703-16. 

Li, Y, Yao, M., Li, T.-T. et al. 2013. Simultaneous electrochemical determination of uric acid and dopamine in the presence of ascorbic acid using nitrogen-doped carbon hollow spheres. Anal. Methods 5 3635-3638. 

Keeley, G. R, McEvoy, N., Nolan, H. et al. 2012. Simultaneous electrochemical determination of dopamine and paracetamol based on thin pyrolytic carhon films. Anal. Methods 4 2048. 

L. Yang, S. Liu, Q. Zhang, F. Li, Simultaneous electrochemical determination of dopamine and ascorbic acid using AuNPs polyaniline core-shell nanocomposites modified electrode, Talanta 89 (2012) 136-141. 

Huang JS, Liu Y, Hou HQ, You TY (2008) Simultaneous electrochemical determination of dopamine, uric acid and ascorbic acid using palladium nanopaiticle-loaded carbon nemofibers modified electrode. Biosens Bioelectron 24 632-637... 

Jia N, Wang Z, Yang G, Shen H, Zhu L (2007) Electrochemical properties of ordered mesoporous carbon and its electroanalytical application for selective determination of dopamine. Electrochem Commun 9 233-238... 

Because LCEC had its initial impact in neurochemical analysis, it is not, surprising that many of the early enzyme-linked electrochemical methods are of neurologically important enzymes. Many of the enzymes involved in catecholamine metabolism have been determined by electrochemical means. Phenylalanine hydroxylase activity has been determined by el trochemicaUy monitoring the conversion of tetrahydro-biopterin to dihydrobiopterin Another monooxygenase, tyrosine hydroxylase, has been determined by detecting the DOPA produced by the enzymatic reaction Formation of DOPA has also been monitored electrochemically to determine the activity of L-aromatic amino acid decarboxylase Other enzymes involved in catecholamine metabolism which have been determined electrochemically include dopamine-p-hydroxylase phenylethanolamine-N-methyltransferase and catechol-O-methyltransferase . Electrochemical detection of DOPA has also been used to determine the activity of y-glutamyltranspeptidase The cytochrome P-450 enzyme system has been studied by observing the conversion of benzene to phenol and subsequently to hydroquinone and catechol... 

Brock, John W., Jeffrey P. Ng, and Joseph B. Justice Jr. 1990. "Effect of Chronic Cocaine on Dopamine Synthesis in the Nucleus Accumbens as Determined by Microdialysis Perfusion with NSD-10." Neuroscience Letters 117 234-39. Broderick, Patricia A. 1985. "In Vivo Electrochemical Studies of Rat Striatal Dopamine and Serotonin Release After Morphine." Life Sciences 36 2269-75. 

Determination of dopamine is by HPLC and electrochemical detection and is very similar to that described previously for the CSF determination of biogenic amines. 

Neurotransmitters have also been detected on microchips using electrochemical detection, eliminating the need for on-chip reactions or derivitization. Amperometric detection, a current change when an analyte passes the detection electrodes, was demonstrated on a microchip for the determination of dopamine concentrations in standard solutions [10], The microdevice developed in this... 

Electrochemical detection was easily employed for the determination of uric acid in urine, abnormal concentrations of which have been linked to several disease states [14]. A glass/PDMS hybrid device with an off-chip platinum electrode was used to evaluate standard samples for both dopamine and uric acid. The linear responses for dopamine and uric acid were 1-165 and 15-110 pM, respectively, with a 1 pM limit of detection for both. Normal concentrations of uric acid in urine are 800-8000 pM, thus a 50 to 75-fold dilution was used with the urine samples analyzed to place them within the linear range of the detection method. Uric acid concentrations in these urine samples were confirmed using the clinically accepted method. This new method should allow clinical detection of both abnormally high and abnormally low uric acid concentrations in urine samples on a microdevice. 

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. 

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