The current food safety testing system, based on laboratory-based
quantification, is difficult to scale up in line with the growth in
the export market and does not enable traceability through the nodes
of the food supply system. Screening assays, for example, lateral
flow assays (LFAs), can improve traceability but often lack the required
reliability to guarantee compliance. Here, we present an alternative
pipeline for secure on-site compliance testing, using allergens as
a case study. The pipeline features smartphone-driven LFA quantification
and an liquid chromatography–mass spectrometry (LC–MS)
method enabling direct quantification of the allergens contained in
the LFA. The system enables swift and objective screening and provides
a control measure to verify LFA assay reliability. For the smartphone
assay, 8-bit RGB and grayscale colorimetric channels were compared
with 16-bit raw intensity values. The latter outperformed RGB and
grayscale channels in sensitivity, repeatability, and precision, while
ratiometric ambient light correction resulted in excellent robustness
for light-intensity variation. Calibration curves for peanut determination
using two commercial LFAs featured excellent analytical parameters
(R
2 = 0.97–0.99; RSD 7–1%;
LOD 3–7 ppm). Gluten determination with a third commercial
LFA was equally established. A prediction error of 13 ± 11% was
achieved for the best performing assay. Good performance–calibration
curves (R
2 = 0.93–0.99) and CVs
(<15%)– were observed for the analyte quantification from
the LFA by LC–MS. The LOD for the LC–MS assay was 0.5
ppm, well below the LODs reported for the LFAs. This method creates
a digital, fast, and secure food safety compliance testing paradigm
that can benefit the industry and consumer alike.
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