Study of metal release from stainless steels in simulated food contact by means of total reflection X-ray fluorescence

• A release test to simulate food contact with stainless steel was optimized.
• Quantitative analysis of release tests water solutions was performed by TXRF.
• TXRF has the advantage of simultaneous identification of all elements present in solutions.
• The developed procedure is useful to prescribe the preferential use of a material for food utensils.

This study shows a reliable procedure to prescribe the preferential use of a material for food contact. Release tests with optimized parameters were performed on six different stainless steel accepted for the use in food contact: AISI 420, AISI 430, AISI 202, AISI 303, AISI 304, and AISI 316. Total reflection X-ray fluorescence spectroscopy was used to measure the concentration of Cr, Mn and Ni in contact solutions from release tests. Results show that AISI 202 and 430 release the lowest amount of Mn, Cr and Ni. While, AISI 420 is the worst material, exceeding the limit set in the Italian regulation for all the three metals of interest. One sample was selected to test the reproducibility of TXRF measurements performed in three different laboratories around the world. Results show that quantitative analyses by means of TXRF satisfy the requirements of this field of application.