Quantification of Nitrite in Food and Water Samples Using the Griess Assay and Digital Images Acquired Using a Desktop Scanner

Autor/inn/en	Filgueiras, Matheus Fernandes; de Jesus, Paulo Cesar; Borges, Endler Marcel
Titel	Quantification of Nitrite in Food and Water Samples Using the Griess Assay and Digital Images Acquired Using a Desktop Scanner
Quelle	In: Journal of Chemical Education, 98 (2021) 10, S.3303-3311 (9 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Zusatzinformation	ORCID (Borges, Endler Marcel)
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0021-9584
DOI	10.1021/acs.jchemed.0c01392
Schlagwörter	Science Instruction; Water; Food; Science Experiments; Heat; Science Laboratories; Hazardous Materials; Foreign Countries; Laboratory Equipment; Brazil + Suchen Sie Ihr Suchwort? Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Wasser; Lebensmittel; Hitze; Hazardous substance; Gefahrstoff; Ausland; Laborausstattung; Brasilien
Abstract	The Griess assay is widely used by regulation agencies as an official method for nitrite quantification in water and food samples. In Brazil, the official method, which has been used to determine nitrite in food, was described by Instituto Adolfo Lutz (283/IV) in 1984. It uses 8 mL of reactants and provides 50 mL (reactants plus sample) of waste per sample analyzed. Here, students scaled down the official method 50 times and quantified nitrite in water and food samples by using just 0.2 mL of the Griess reactant and 1 mL of sample. Quantitative analysis was carried out using absorbance measured at 540 nm (standard method) and 96-well-plate images (proposed method) obtained with a desktop scanner. The nitrite was extracted from solid food samples by heating it in a water bath. After heating, sample color and turbidity were eliminated by addition of K[subscript 4][Fe(CN)[subscript 6]] and ZnSO[subscript 4] solutions and filtering. During samples preparation, students evaluate the heating time effect in nitrite extraction from sausage samples using hypothesis tests. Students did a series of matrix matched samples to observe the matrix effect. Students also calculated the detection limit (DL) and the quantification limit (QL) for the proposed method (1.35 and 4.1[mu]mol/L nitrite, respectively) and for the standard method (1.1 and 3.4 [mu]mol/L nitrite, respectively). DL and QL were determined using the standard deviation of the lowest concentration point on the standard curve. The major pedagogical value of this laboratory class was to scale down the official method and use it to prepare and analyze a solid food sample. As a learning model, finding real water samples, which have nitrite concentrations larger than method QL, was a hard task, but all sausage samples analyzed had larger nitrate concentrations than the method QL and nitrite quantification in sausages was a good learning model. (As Provided).
Anmerkungen	Division of Chemical Education, Inc. and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2024/1/01