title: Evaluation of the results from an inter-laboratory comparison study of the determination of acrylamide in crispbread and butter cookies.
abstract: Analytical methods currently employed for determination of acrylamide (AA) in two carbohydrate-rich food samples, crispbread and butter cookies, obtained commercially, and native and spiked bread extract samples have been evaluated in a collaborative study. The objective of the study was to obtain information about the performance of the participating laboratories when analysing samples with an AA content close to the limit of quantification ( LOQ) and at a higher AA level, and to investigate the influence of sample-preparation procedures on the results of the analysis. For this purpose an aqueous native extract of white bread crumb, a fortified extract, and AA standard solutions, the analyte content of which were not disclosed to the participants, were included in the study. A total of 62 laboratories, applying seven different measurement techniques and a broad spectrum of analyte extraction and sample-preparation procedures reported their analytical results. Because the measurement data were not normally distributed, they were evaluated by application of robust statistics. The relative performance of the laboratories was highlighted by calculation of z-scores. For the crispbread sample, especially, a large percentage of the calculated z-scores were outside the satisfactory range. From their distribution it became obvious that one of the analytical techniques might be biased, if not applied correctly. Consequently, the impact of the applied methods was examined in more detail. Information about the analytical technique, extraction solvent, quantity weighed, calibration method, clean-up, and the experience of the participating laboratories were extracted from the analytical protocols and transcribed into a data matrix which was evaluated by multifactor analysis of variance. The applied measurement technique seems to have a statistically significant influence on the analytical results.
authors.affiliation: European Commission, Directorate General Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg, 2440 Geel, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wenzl
authors.forename: Beatriz
authors.initials: B
authors.lastname: de la Calle
authors.forename: R
authors.initials: R
authors.lastname: Gatermann
authors.forename: K
authors.initials: K
authors.lastname: Hoenicke
authors.forename: F
authors.initials: F
authors.lastname: Ulberth
authors.forename: Elke
authors.initials: E
authors.lastname: Anklam