Quantitative Detection of Nitrite in Food Samples Based on Digital Image Colourimetry by Smartphone

Abstract

A novel colourimetric method for the detection of nitrite in food samples using digital image colourimetry (DIC) by smartphone is developed. Nitrite directly oxidise 3,3′,5,5′‐tetramethylbenzidine (TMB) to form a yellow TMB diimine (oxTMB). A smartphone was used to capture the image of an inherent colour variation and analyse the image with the RGB (red, green, and blue) model, achieving the quantitative detection of nitrite. Linear response for the detection of nitrite was obtained from 10 μmol L−1 to 440 μmol L−1 and the limit of quantification was 2.34 μmol L−1. The applicability of the method was confirmed by the detection of nitrite in cabbage, pickle, and ham. The recovery was varied in the range from 96.2 % to 108.2 % with a relative standard deviation of less than 5.0 %. The simple, sensitive, and inexpensive method was an alternative for the detection of nitrite in food samples.

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

“…High nitrite levels have negative effects on humans. For examples, nitrite reacts irreversibly with hemoglobin in the bloodstream, reducing the capacity of blood to carry oxygen, and it can also react with secondary amines and amides in the stomach to form carcinogenic N -nitrosamines …”

“…For examples, nitrite reacts irreversibly with hemoglobin in the bloodstream, reducing the capacity of blood to carry oxygen, and it can also react with secondary amines and amides in the stomach to form carcinogenic N-nitrosamines. 5 There are several methods for nitrite quantification such as spectrophotometric, chemiluminescent, electrochemical, chromatographic, spectrofluorimetric, and electrochemiluminescent methods. Moorcroft et al 6 reviewed the methods described in the literature until 2001, while Wang et al 4 reviewed methods described in the literature from 2001 to 2017.…”

Ratiometric Colorimetric Detection of Nitrite Realized by Stringing Nanozyme Catalysis and Diazotization Together

“…As demonstrated in Figure S14 (Supplementary Materials), when nitrite and TMB are incubated together at room temperature with no addition of the nanozyme, the UV-vis spectrum of the mixture provides a notable peak at 652 nm, which is assigned to the TMB oxidation to TMBox. Such a phenomenon involves the redox reaction between nitrite and TMB [63]. Additionally, an absorption signal centered at 439 nm is observed, which is due to the diazotization reaction of nitrite and TMB [30].…”

Deep eutectic solvent-based dispersive liquid–liquid microextraction followed by smartphone digital image colorimetry for the determination of carbofuran in water samples

“…27 DIC has more accurate detection results and a wider detection range than visual colorimetry. 26,28 DIC is an image analysis-based technique and an alternative for quantitative and qualitative analysis of various samples. [29][30][31] The RGB color model can process images acquired using accessible smartphones.…”