Development of a Paper-Based Sensor Compatible with a Mobile Phone for the Detection of Common Iron Formulas Used in Fortified Foods within Resource-Limited Settings.

Anna W Waller,Dylan J Rigsby,Juan E Andrade,Marco Toc,Marcela Gaytán-Martínez

doi:10.3390/nu11071673

Anna W Waller, Dylan J Rigsby + Show 3 more

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https://doi.org/10.3390/nu11071673

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Abstract

A lack of quality control tools limits the enforcement of fortification policies. In alignment with the World Health Organization’s ASSURED criteria (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverable), a paper-based assay that interfaces with a smartphone application for the quantification of iron fortificants is presented. The assay is based on the Ferrozine colorimetric method. The reaction started after deposition of the 5 µL aqueous sample and drying. After developing color, pixel intensity values were obtained using a smartphone camera and image processing software or a mobile application, Nu3px. From these values, the actual iron concentration from ferrous sulfate and ferrous fumarate was calculated. The limits of detection, quantification, linearity, range, and errors (systematic and random) were ascertained. The paper-based values from real samples (wheat flour, nixtamalized corn flour, and infant formula) were compared against atomic emission spectroscopy. The comparison of several concentrations of atomic iron between the spectrophotometric and paper-based assays showed a strong positive linear correlation (y = 47.01x + 126.18; R2 = 0.9932). The dynamic range (5.0–100 µg/mL) and limit of detection (3.691 µg/mL) of the paper-based assay are relevant for fortified food matrices. Random and systematic errors were 15.9% and + 8.65 µg/g food, respectively. The concept can be applied to limited-resource settings to measure iron in fortified foods.

Highlights

IntroductionSensor technologies detecting micronutrients (e.g., vitamins and minerals such as iron and vitamin A) have been at the forefront of technology development
In recent years, sensor technologies detecting micronutrients have been at the forefront of technology development
There is a limited number of commercially available sensors capable of detecting iron in foods within resource-limited settings, leaving atomic spectroscopy as the most accurate and reliable, but costly, option for monitoring and evaluation of food fortification programs [8]

Summary

Introduction

Sensor technologies detecting micronutrients (e.g., vitamins and minerals such as iron and vitamin A) have been at the forefront of technology development These efforts have largely focused on the development of diagnostic tools for assessment of status or deficiency biomarkers in biological samples [1,2,3,4,5]. Few of these sensors, are designed to detect micronutrients in food matrices and only very few of those available reach proof-of-concept. There is a limited number of commercially available sensors capable of detecting iron in foods within resource-limited settings, leaving atomic spectroscopy as the most accurate and reliable, but costly, option for monitoring and evaluation of food fortification programs [8]

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