Electrochemical Studies of an Iron Porphyrin Immobilized on Nb₂O₅/SiO₂ and Its Application for Simultaneous Determination of Dopamine and Ascorbic Acid Using Multivariate Calibration Methodology

Abstract

This paper shows an application of a first generation porphyrin, FeTPPCl 5,10,25,20-tetraphenylporphyrin iron(III) chloride (FeTPPCl or FeTPP þ ) immobilized on a inorganic matrix, SiO 2 /Nb 2 O 5 (niobium oxide grafted on silica gel surface, designated as SiNb) to the preparation of a carbon paste electrode (CPE). The carbon paste modified with a FeTPP þ immobilized on SiO 2 /Nb 2 O 5 (SiNb), designated as CPE/SiNb/FeTPP, was applied for simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA). Because of the overlapping of the voltammetric peaks of DA and AA, the multivariate calibration methodology based on partial least square regression (PLSR) was proposed. The data pre-treatment used in this process was mean centering and to choose the principal components number a cross validation procedure was used (leave-one-out). Five principal components were necessary to obtain the lowest PRESS (prediction residual error sum of squares). The statistics showed that this model explains approximately 95.2% of the variance from the data set. Using this model, high correlation between actual and predicted concentrations was observed, mainly for higher dopamine (maximum relative error of 8%) and ascorbic acid (maximum relative error of 10%) concentrations. For low analytes concentrations the relative error increases to 35% for AA. Considering the similarity of the voltammetric response of the analytes, the results obtained were satisfactory and showed the promissory capability of the CPE/SiNb/FeTPP coupled multivariate calibration methods for simultaneous voltammetric analysis of DA and AA.

Review of recent advances in analytical techniques for the determination of neurotransmitters

“…The need for better electrode selectivity motivated the testing of a large and varied group of electrode modifications. DA was detected in the presence of ascorbic acid by use of surface modifications including clinoptilolite with Nafion,[102] iron nanoparticles dispersed in Nafion,[103, 104] single wall carbon nanotubes with Nafion,[105] MWCNTs which incorporated β-cyclodextrin,[106] cobalt phthalocyanine,[107] a mixture of gold and palladium nanoparticles,[108] tyrosinase,[109] cysteine,[110] poly(p-toluene sulfonic acid),[111] iron porphyrin immobilized in a niobium oxide silica gel,[112] polyanaline,[106] 3,5-dihydroxy benzoic acid,[113] melanic polymers electrogenerated from catecholamines,[114, 115] a carbon nanoparticle–poly(diallyldimethylammonium chloride) film,[116] polycarbazole and poly(carbazoleco-p-tolylsulfonyl pyrrole),[117] a cetylpyridine bromide/chitosan composite film,[118] and a calix[4] arene crown-4 ether film. [119] Interference of ascorbic acid with the detection of DA was also eliminated by the development of a dual amperometric and conductometric device.…”

“…[120] Multivariate calibration methods have also be useful in separating the signal due to DA from that of ascorbic acid. [112]…”

High density heterogenisation of molecular electrocatalysts in a rigid intrinsically microporous polymer host

“…These methods require suitable surfaces, high surface area, and carefully executed surface chemistry. An alternative strategy can be based on porous host materials such as conducting polymers, 6 network polymers, 7 zeolites, 8 intercalation materials, 9 solgels, 10 which in turn need to be immobilised or pasted 11 into the electrode material. In particular gels and polymer hosts are beneficial and readily applied, although stability of these host materials, aging, cross-linking, and non-rigidity causing mobility of guest species can be problematic.…”

Preparation and Electrochemical Characterization of a Carbon Ceramic Electrode Modified with Ferrocenecarboxylic Acid

“…This paper reports the development of a CCE modified with ferrocenecarboxylic acid (CCE/Fc). The electrode was characterized by voltammetric techniques and applied as an electrochemical sensor for dopamine, which is an important neurotransmitter and is related to several diseases such as schizophrenia and parkinsonism [ 27 , 28 ]. Therefore, the development of methods for the quantification of dopamine in blood and biological fluids is the subject of intense current investigation [ 29 – 31 ].…”