Abstract
This study describes the development of a new sensor with applicability in the determination and quantification of yjr essential amino acid (AA) L-tryptophan (L-TRP) from pharmaceutical products. The proposed sensor is based on a carbon screen-printed electrode (SPCE) modified with the conductor polymer polypyrrole (PPy) doped with potassium hexacyanoferrate (II) (FeCN). For the modification of the SPCE with the PPy doped with FeCN, the chronoamperometry (CA) method was used. For the study of the electrochemical behavior and the sensitive properties of the sensor when detecting L-TRP, the cyclic voltammetry (CV) method was used. This developed electrode has shown a high sensibility, a low detection limit (LOD) of up to 1.05 × 10−7 M, a quantification limit (LOQ) equal to 3.51 × 10−7 M and a wide linearity range between 3.3 × 10−7 M and 1.06 × 10−5 M. The analytical performances of the device were studied for the detection of AA L-TRP from pharmaceutical products, obtaining excellent results. The validation of the electroanalytical method was performed by using the standard method with good results.
Highlights
Tryptophan (TRP), with the molecular formula C11H11N2O2, is a well-known substance, being part of the essential amino acid (AA) category that cannot be produced naturally by the human body [1]
TRP works as a chemical precursor for 5-hydroxytryptophan (5-HTP), as well as a coenzyme for the nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) [3]
These methods proved to be expensive and required time to obtain the results, facts that led to more versatile methods that were based on electroanalysis using sensors [29] and biosensors for the much more simple, sensible and selective detection of TRP from pharmaceutical, biological and food products, using electrochemical detection methods such as cyclic voltammetry (CV) [30,31], differential pulse voltammetry (DPV) [20,30] and square wave voltammetry (SWV) [9,32]
Summary
Tryptophan (TRP), with the molecular formula C11H11N2O2, is a well-known substance, being part of the essential AA category that cannot be produced naturally by the human body [1]. Reference [[[[[[[11212228939678[[[[[–]],]]]11221[[[[[[2]12122128936919693782–]]],,,]–]]]22]]22214122,,,]222] 544,],RR225e5e]f]feerreennccee [2[278]] [28] These methods proved to be expensive and required time to obtain the results, facts that led to more versatile methods that were based on electroanalysis using sensors [29] and biosensors for the much more simple, sensible and selective detection of TRP from pharmaceutical, biological and food products, using electrochemical detection methods such as CV [30,31], differential pulse voltammetry (DPV) [20,30] and square wave voltammetry (SWV) [9,32]. The analytical performances of the sensor developed in this study were evaluated in model solutions and in solutions obtained through pharmaceutical products with distinct concentrations of L-TRP from different manufacturers, followed by validation with the standard method based on Fourier-transform infrared (FT-IR) spectroscopy
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