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

Area of Science:

• Food Science
• Analytical Chemistry
• Public Health Nutrition

Background:

• Quality control for food fortification in low-income countries is challenging due to the absence of accessible sensing tools.
• Iron fortification of staple foods like flour is crucial for combating deficiencies, but requires reliable monitoring.
• Existing methods for iron determination are often complex and expensive, limiting their use in resource-limited settings.

Purpose of the Study:

• To field validate a paper-based, smartphone-assisted colorimetric assay (Nu3Px) for determining iron content in fortified flours.
• To compare the performance of Nu3Px against the gold standard atomic emission spectrometry (AES).
• To assess the feasibility of using Nu3Px with affordable sampling tools for quality control in food fortification programs.

Main Methods:

• Field validation of the Nu3Px assay using commercial iron-fortified flours from Mexico.
• Comparison of Nu3Px results with atomic emission spectrometry (AES) for iron determination.
• Method validation experiments to quantify Nu3Px's error parameters (bias and random error).
• Pilot testing of Nu3Px for batch decision-making based on Mexico's fortification policy.
• Development and evaluation of an alternative, affordable sampling procedure.

Main Results:

• Nu3Px demonstrated low random error (12%) and minimal bias (1.79 ± 9.99 μg Fe/g flour) when compared to AES.
• Iron content in Mexican corn flours varied significantly, ranging from 23% to 39%.
• Nu3Px and AES yielded similar classifications regarding Mexico's fortification policy thresholds.
• The affordable sampling kit coupled with Nu3Px showed high correlation (r = 0.952, p = 0.01) with traditional sampling methods.
• Nu3Px met the performance parameters required for corn flour fortification programs.

Conclusions:

• The Nu3Px assay, combined with affordable sampling tools, provides a reliable and accessible method for iron determination in fortified flours.
• This technology can significantly enhance quality control in food fortification programs, particularly in low-income settings.
• The smartphone-assisted approach democratizes access to essential food safety and nutritional monitoring tools.