Determination of peanut allergens in cereal‐chocolate‐based snacks: metal‐tag inductively coupled plasma mass spectrometry immunoassay versus liquid chromatography/electrospray ionization tandem mass spectrometry

Abstract

A comparison of two methods for the identification and determination of peanut allergens based on europium (Eu)‐tagged inductively coupled plasma mass spectrometry (ICP‐MS) immunoassay and on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) with a triple quadrupole mass analyzer was carried out on a complex food matrix like a chocolate rice crispy‐based snack. The LC/MS/MS method was based on the determination of four different peptide biomarkers selective for the Ara h2 and Ara h3/4 peanut proteins. The performance of this method was compared with that of a non‐competitive sandwich enzyme‐linked immunosorbent assay (ELISA) method with ICP‐MS detection of the metal used to tag the antibody for the quantitative peanut protein analysis in food. The limit of detection (LOD) and quantitation of the ICP‐MS immunoassay were 2.2 and 5 µg peanuts g⁻¹ matrix, respectively, the recovery ranged from 86 ± 18% to 110 ± 4% and linearity was proved in the 5–50 µg g⁻¹ range. The LC/MS/MS method allowed us to obtain LODs of 1 and 5 µg protein g⁻¹ matrix for Ara h3/4 and Ara h2, respectively, thus obtaining significantly higher values with respect to the ELISA ICP‐MS method, taking into account the different expression for concentrations. Linearity was established in the 10–200 µg g⁻¹ range of peanut proteins in the food matrix investigated and good precision (RSD <10%) was demonstrated. Both the two approaches, used for screening or confirmative purposes, showed the power of mass spectrometry when used as a very selective detector in difficult matrices even if some limitations still exist, i.e. matrix suppression in the LC/ESI‐MS/MS procedure and the change of the Ag/Ab binding with matrix in the ICP‐MS method. Copyright © 2008 John Wiley & Sons, Ltd.