Validation by Collaborative Trial of an Isotope Dilution Liquid Chromatographic Tandem Mass Spectrometric Method to Determine the Content of Acrylamide in Roasted Coffee

Abstract

A method for the determination of acrylamide in roasted coffee was subjected to an inter-laboratory comparison study. The aim was to extend the scope of a method already standardised for the determination of acrylamide in bakery and potato products to include roasted coffee. Modifications of the already standardised method were therefore kept to a minimum. The method was based on aqueous extraction of the roasted coffee matrix and solid phase extraction (SPE) clean-up followed by isotope dilution high performance liquid chromatography with tandem mass spectrometric detection (LC-MS/MS). The test portion of the sample was spiked with stable isotope labelled acrylamide and extracted on a mechanical shaker with n-hexane and water for one hour. The sample extract was centrifuged, the organic phase was discarded, and a portion of the aqueous extract was further cleaned-up by solid phase extraction on an Isolute Multimode cartridge followed by a second clean-up step on an Isolute ENV+ cartridge. The volume of the acrylamide-containing fraction eluted from the second SPE column was reduced by evaporation and analysed by reverse-phase high performance liquid chromatography (HPLC) with tandem mass spectrometric detection.

Three coffee samples and one aqueous acrylamide standard solution were sent to 11 laboratories from 8 EU Member States. All samples were sent as blinded duplicates.

Based on the reported results the relative standard deviations for reproducibility (RSDR) were 11.5 % at a level of 160 µg/kg, 10.1 % at a level of 263 µg/kg, and 9.6 % at a level of 585 µg/kg. The values for repeatability (RSDr) in those materials ranged from 1 % to 3.5 %. The method performance parameters are satisfying with regard to internationally accepted criteria. Hence the method would be suitable for the enforcement of regulatory limits.