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

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.

Stakeholder’s Perceptions of Mexico’s Federal Corn Flour Fortification Program: A Qualitative Study

“…The ASSURED criteria can be applied to the development of inexpensive micronutrient analysis tools to support government food fortification policies in low-resource settings [22]. One example of such appropriate technology is the Nu3px smartphone iron sensor for fortified foods, which is a cost-effective and user-friendly alternative to its traditionally used gold standard counterpart, atomic emission spectroscopy [24]. Sensors can be used to monitor compliance and efficacy of food fortification programs, a critical component of fortification policies to fulfill the program's stated objectives [1].…”

“…The evaluation should focus on all sectors of society who may benefit from this program, including rural, urban, and other geographical zones, and different socioeconomic strata [1]. The authors recommend a more thorough and frequent internal monitoring system (such as implementing Nu3px, an alternative ASSURED-designed iron quantification tool previously mentioned) to ensure quality fortified products [24]. Finally, the NOM could be modified to include a standardized protocol for actions to take in the case of non-compliance.…”

In-Country Method Validation of a Paper-Based, Smartphone-Assisted Iron Sensor for Corn Flour Fortification Programs

“…Recent paper-based assays designed for food matrices have focused on the detection and quantification of additives (i.e., food colorings), pathogens, pesticides, herbicides, and toxic trace metals in foods [13][14][15][16]. Due to the lack of commercially available ASSURED-designed sensors to detect nutrients in fortified foods, our team developed a paper-based, smartphone-assisted assay for the determination of iron in fortified foods (also known as Nu3Px) [17]. The chemicals used in the ferrozine reaction were embedded in the paper sensor to measure different iron formulations employed in food fortification.…”

Colorimetric Method for Instant Detection of Lysine and Arginine Using Novel Meldrum's Acid‐Furfural Conjugate

“…[1] Detection of biochemical species and vital nutrients is not only important in medical science but also in the food industry. [2] Among various important nutrients responsible for proper biochemical functioning, essential amino acids are a vital part of healthy human diet, disbalance in their intake can lead to possible adverse health effects. [3] Therefore, food industry is continuously looking for methods those can quantify the presence of essential amino acids that human body cannot synthesize on its own.…”

“…Efficient and selective methods for colorimetric detection of trace elements and substances are the bases of modern assay development [1] . Detection of biochemical species and vital nutrients is not only important in medical science but also in the food industry [2] . Among various important nutrients responsible for proper biochemical functioning, essential amino acids are a vital part of healthy human diet, disbalance in their intake can lead to possible adverse health effects [3] .…”