Reply to the ‘Comments on “Soxhlet extraction of acrylamide from potato chips”’ by K. Grob et al., Analyst, 2004, 129, 92; J. W. DeVries et al., Analyst, 2004, 129, 93; M. Tanaka et al., Analyst, 2004, 129, 96

According to Grob et al.,¹ Soxhlet extraction of acrylamide from potato chips, using methanol as a solvent, overestimates the amount of acrylamide extracted. They performed experiments demonstrating formation of acrylamide, from asparagine and fructose, in boiling methanol. We checked the experiments by Grob et al.¹ and received analogous results. Later, DeVries and Post² performed similar experiments coming to the same conclusion as Grob et al.¹ Finally, Tanaka et al.³ proved formation of acrylamide in methanol extracts from potato chips during Soxhlet extraction.

At the time of our study, there were no published results indicating formation of acrylamide at 65 °C in methanol extracts. In the new experiments related above, a substantial but very slow formation of acrylamide was detected during those conditions. Clearly, formation of acrylamide during extraction accounts for a part of our measured values. However, this new formation does not conclusively explain the difference compared to the other methods used.

To be noted, recently a large proficiency test⁴ demonstrated that “the current methods should be verified”. One conclusion from this test was: “the extraction procedure seems to be a crucial step for the analysis of acrylamide for some matrices”.

References

1. K. Grob, M. Biedermann, K. Hoenicke and R. Gatermann, Analyst, 2004, 129, 92.
2. J. W. DeVries and B. E. Post, Analyst, 2004, 129, 93.
3. M. Tanaka, Y. Yoneda, Y. Terada, E. Endo and T. Yamada, Analyst, 2004, 129, 96.
4. C. Fauhl, H. Klaffke, W. Mathar, R. Palavinskas, and R. Wittkowski, Acrylamide Interlaboratory Study 2002, Report on Results 2003-02-10, Federal Institute for Risk Assessment, D-14195 Berlin.

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