title: Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode.
abstract: Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl₄ solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5-50 mg·L(-1) nitrite with a limit of detection (LOD) of 0.12 mg·L(-1). Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO₂(-) solution and in sausage sample solution, to which different concentrations of NO₂(-) standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.
authors.affiliation: Analytical Chemistry Division, Chemistry Department, Faculty of Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey. auzer@istanbul.edu.tr.
authors.forename: Ayşem
authors.initials: A
authors.lastname: Üzer
authors.affiliation: Analytical Chemistry Division, Chemistry Department, Faculty of Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey. sener.saglam@istanbul.edu.tr.
authors.forename: Şener
authors.initials: Ş
authors.lastname: Sağlam
authors.affiliation: Analytical Chemistry Division, Chemistry Department, Faculty of Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey. ziya.can@istanbul.edu.tr.
authors.forename: Ziya
authors.initials: Z
authors.lastname: Can
authors.affiliation: Analytical Chemistry Division, Chemistry Department, Faculty of Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey. ercag@istanbul.edu.tr.
authors.forename: Erol
authors.initials: E
authors.lastname: Erçağ
authors.affiliation: Analytical Chemistry Division, Chemistry Department, Faculty of Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey. rapak@istanbul.edu.tr.|Turkish Academy of Sciences (TUBA) Piyade st. No: 27, 06690 Çankaya Ankara, Turkey. rapak@istanbul.edu.tr.
authors.forename: Reşat
authors.initials: R
authors.lastname: Apak
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D015374:Biosensing Techniques; D003124:Colorimetry; D058266:Dielectric Spectroscopy; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D005520:Food Preservatives / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D009573:Nitrites / Q000032:analysis*; D058105:Polymerization; D011108:Polymers / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D005520:Food Preservatives; D009573:Nitrites; D011108:Polymers; D013438:Sulfhydryl Compounds; D006046:Gold; C064316:4-aminothiophenol
keywords: gold electrode; gold nanoparticles; modified electrode; nitrite determination; square wave voltammetry (SWV)