Development of a Sensor Based on Modified Carbon Paste with Com Iron(III) Protoporphyrin Immobilized on SiNbZn Silica Matrix for L‐tryptophan Determination

Abstract

In this work, SiO2/Nb2O5/ZnO prepared by the sol‐gel processing method was used as substrate base for immobilization of the protoporphyrin‐IX ion. Iron(III) ion was inserted into the porphyrin ring (SiNbZn‐PPFe). A simple square wave voltammetry method based on a composite sensor carbon paste electrode of this material,designed as EPC‐SiNbZn‐PPFe, was developed and validated successfully for the determination of L‐tryptophan (Trp). The optimum conditions were obtained by using sensor modified with 18.00 mg SiNbZn‐PPFe material, 12.00 mg graphite powder and 6.0 μL mineral oil and phosphate buffer 0.3 mol L−1 pH 7.0. The sensitivity of the sensor was found to be 0.523 AL mol −1, linear range from 10 to 70 μmol L−1 and limit of detection of 3.28 μmol L−1. Therefore, the developed method was successfully applied for the Trp determination in real samples of pharmaceutical formulation and can be used for routine quality control pharmaceutical formulations containing Trp.

Versatile Metalloporphyrin‐Based Electrochemical Sensing Applications: From Small Gasotransmitters to Macromolecules

“…In this section we will discuss some of the sensors used for the detection of amino acids (L-Tryptophan, L-Tyrosine, L-Cysteine, L-Histidine), [132,133] volatile organic compounds (VOCs), [134][135][136][137][138] herbicides (dimethoate, methyl parathion, glyphosate), [139,140] relevant organic acids (nicotinic, pipecolic, uric, folic, sorbic and ascorbic acid), [141][142][143][144][145][146][147] polyphenols, [148][149][150][151] pharmaceutical compounds (sildenafil citrate, sulfadiazine, sulfamethoxazole, isoniazid, chloramphenicol, ibuprofen, trimethoprim, diclofenac, acetaminophen), [151][152][153][154] and hormones and neurotransmitters (cortisol, 17β-estradiol, levodopa, carbidopa, dopamine). [145,147,[155][156][157][158] The detection methods for amino acids and pharmaceutical compounds have been described in detail in the reviews of Cruz-Navarro et al [19] and Gonçalves et al [159] For a more detailed description of all compounds see Table S1.…”

Porphyrins-as Active Materials in the Design of Sensors. An Overview

“…Nunes da Silva et al 16 developed a sensor based on modified carbon paste with iron (III) protoporphyrin immobilized on SiNbZn silica matrix for L-tryptophan (L-Trp) determination. The carbon paste electrodes (CPEs) have been extensively used as a suitable matrix for the construction of the sensors, due to the reliability of the sensors' design.…”