The content of heavy metals in food packaging paper: an atomic absorption spectroscopy investigation

Abstract

The levels of four representative heavy metals — Cd, Cr, Pb and Hg — have been measured by atomic absorption spectroscopy (AAS) in 12 different samples of paper: 7 different kinds of food packaging paper, commonly employed in Italy (brown and white bread bags, brown and white bakery paper, white bakery bag, butcher's paper and salami paper), and 5 samples of non-food paper (two newspapers, one weekly magazine, one blue and one yellow notebook), assayed, for comparative purposes, in the same experimental conditions. The levels of heavy metals have been measured in all the samples according to two different procedures: i) after immersion in distilled water for 24 h at T = 23%; and ii) after immersion in 3% v/v acetic acid for 24 h at T = 40 °C. The results of the present investigation show that all samples of food packaging paper contain concentrations of heavy metals that are generally lower than those detected in samples of common paper. Moreover, our results show that there is a remarkable difference among the levels of heavy metals depending on the procedure of sample pretreatment. Our observation points out that the pretreatment usually indicated as ‘migration test’ (performed in 3% v/v acetic acid at T = 40 °C), being remarkably more drastic than the ‘extraction test’ (performed in distilled water at T = 23 °C), should be requested in all those cases in which a direct contact occurs between the food and the paper packaging.