Multi-Allergen Quantification in Food Using Concatemer-Based Isotope Dilution Mass Spectrometry: An Interlaboratory Study

BACKGROUND: Food allergen analysis is essential for the development of a risk-based approach for allergen management and labeling. Mass spectrometry has become a method of choice for allergen analysis, even if quantification remains challenging. Moreover, harmonization is still lacking between laboratories, while interlaboratory validation of analytical methods is necessary for such harmonization.

OBJECTIVE: This collaborative study aimed to evaluate the potential of mass spectrometry for food allergen detection and quantification using a standard addition quantification strategy and a stable isotope-labeled concatemer as an internal standard.

METHODS: In-house-produced test material (cookies), blank and incurred with four allergens (egg, milk, peanut and hazelnut), allergen standards, an internal standard and the complete methodology (including sample preparation and UHPLC-MS/MS method) were provided to nine laboratories involved in the study. Method sensitivity and selectivity were evaluated with incurred test material and accuracy with spiked test material. Quantification was based on the standard addition strategy using certified reference materials as allergen protein standards and a stable isotope-labeled concatemer as an internal standard.

RESULTS: All laboratories were able to detect milk, hazelnut and peanut in the incurred cookies with sufficient sensitivity to reach the AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR® 2016.002). Egg detection was more complicated due to food processing effects, yet five laboratories reached the sensitivity requirements. Recovery results were laboratory dependent. Some milk and hazelnut peptides were quantified in agreement with SMPR by all participants. Furthermore, over 90% of the received quantification results agreed with SMPR for method precision.

CONCLUSION: The encouraging results of this pioneering collaborative study represent an additional step towards harmonization among laboratories testing for allergens.

HIGHLIGHTS: In this pioneer collaborative study, food allergens were analyzed by mass spectrometry with characterized incurred and spiked test materials, calibration with certified reference material and a single stable isotope-labeled concatemer as an internal standard.