Development of Extraction and Analytical Methods of Nitrite Ion from Food Samples: Microchip Electrophoresis with a Modified Electrode

• Published in: Journal of agricultural and food chemistry 2009-05, Vol.57 (10), p.4051-4057
• Main Authors: Shiddiky, Muhammad J. A, Lee, Kyung-Sun, Son, Jungik, Park, Deog-Su, Shim, Yoon-Bo
• Format: Article
• Language: English
• Subjects: Analytical Methods; anions; Biological and medical sciences; chemical concentration; Copper; detection; electrochemistry; Electrodes; electrophoresis; Electrophoresis, Microchip - methods; extraction; Food Analysis - methods; food composition; Food engineering; Food industries; foods; fouling; Fundamental and applied biological sciences. Psychology; General aspects; ham; Methods of analysis, processing and quality control, regulation, standards; nitrates; nitrites; Nitrites - analysis; Nitrites - isolation & purification; optimization; sausages; Silanes; Spectrophotometry, Ultraviolet; validity
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf900230x

Two simple and fast methods for the extraction of the nitrite ion (NO2 −) from food samples have been developed. The methods were characterized by UV−visible spectroscopic and electrochemical measurements, and their performance for NO2 − extraction was compared with a standard method. The extraction methods yielded relative recoveries between 100 and 120% with good reproducibility of 3.9% (RSD, n = 4) in UV−visible experiments. Microchip electrophoresis with electrochemical detection (MCE-ED) coupled with a copper (3-mercaptopropyl)trimethoxysilane [Cu(II)−MPS] complex-modified carbon paste electrode (CPE) has been employed to detect NO2 − in extracted samples. The Cu(II)−MPS complex was synthesized and characterized by voltammetry, XPS, and FT-IR analyses. Experimental parameters affecting the separation and detection performances of the MCE-ED method were assessed and optimized. The potential for the electrocatalytic reduction of NO2 − for MCE-ED was found to be −190 mV (vs Ag/AgCl). When extracted food samples were analyzed by the MCE-ED method, a reproducible response for the NO2 − reduction (RSD of 4.3%) at the modified-CPE reflected the negligible electrode fouling. A wide dynamic range of 1.0−160 ppm was observed for analyzing standard NO2 − with a sensitivity of 0.05106 ± 0.00141, and the detection limit, based on S/N = 3, was found to be 0.35 ± 0.05 ppm. No apparent interference from NO3 −, other inorganic ions, and biological compounds was observed under the optimal experimental conditions. A standard addition method for real samples showed wide concentration ranges of 1.10−155 and 1.2−150 ppm for analyzing NO2 − in ham and sausage samples, respectively.