A Simple Automated Method for the Determination of Nitrate and Nitrite in Infant Formula and Milk Powder Using Sequential Injection Analysis

Abstract

A fast and efficient automated method using a sequential injection analysis (SIA) system, based on the Griess, reaction was developed for the determination of nitrate and nitrite in infant formulas and milk powder. The system enables to mix a measured amount of sample (previously constituted in the liquid form and deproteinized) with the chromogenic reagent to produce a colored substance whose absorbance was recorded. For nitrate determination, an on-line prereduction step was added by passing the sample through a Cd minicolumn. The system was controlled from a PC by means of a user-friendly program. Figures of merit include linearity (r2 > 0.999 for both analytes), limits of detection (0.32 mg kg−1 NO3-N, and 0.05 mg kg−1 NO2-N), and precision (sr%) 0.8–3.0. Results were statistically in good agreement with those obtained with the reference ISO-IDF method. The sampling frequency was 30 hour−1 (nitrate) and 80 hour−1 (nitrite) when performed separately.

Nitrato e nitrito em fórmulas lácteas infantis para crianças menores de 6 meses de idade

“…O primeiro ano de vida é um momento crucial no desenvolvimento humano e a qualidade das fórmulas infantis é muito importante para garantir o bom funcionamento dos sistemas nervoso, reprodutivo, digestivo, respiratório e imunológico (Pereira, et al 2020). O nitrato pode aparecer em leite em pó e nas fórmulas infantis em consequência do processo industrial, como contaminante dos sais adicionados na fabricação de leites fortificados e fórmulas infantis (Pistón et al, 2011). Diferentes estudos mostraram metahemoglobinemia infantil relacionados à água de poço contaminada com nitrito/nitrato, utilizada no preparo de fórmulas infantis (Pereira et al, 2020;Savino et al, 2006).…”

“…O nitrito, por outro lado, é uma consequência da contaminação microbiana ou pode ser adicionado durante o processo de fabricação dos alimentos. As fórmulas infantis em pó não são produtos comercialmente estéreis, e sofrem tratamento térmico durante o processamento, mas, ao contrário dos produtos líquidos, não são expostas a altas temperaturas por tempo suficiente para tornar o produto final embalado comercialmente estéril (Pistón et al, 2011).…”

Portable Colorimetric Hydrogel Test Kits and On-Mobile Digital Image Colorimetry for On-Site Determination of Nutrients in Water

“…Nitrate is detected by reducing it to nitrite and then conducting the Griess reaction. Various reductants have been reported, such as titanium chloride, hydrazine, cadmium [ 13 ], and zinc powder, an environmentally friendly, cost-effective reductant [ 7 , 11 ]. For the molybdenum blue-based method for phosphate detection, ammonium molybdate reacts with orthophosphate under strong acidic conditions to form a Keggin ion and then is reduced by ascorbic acid to generate a molybdenum blue complex [ 14 , 15 ].…”