Setting maximum limits for trace elements in baby food in European legislation: the outcome of International Measurement Evaluation Programme®-33.

The Institute for Reference Materials and Measurements (IRMM) of the Joint Research Centre (JRC), a Directorate-General of the European Commission, operates the International Measurement Evaluation Programme® (IMEP). It organises various types of inter-laboratory comparisons in support of European Union policies. This paper presents the results of a proficiency testing exercise (PT) focusing on the determination of total cadmium (Cd) and total lead (Pb) mass fractions in baby food in support to Commission Regulation (EC) 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. The test material used in this exercise was soya-based baby food formula purchased in a local pharmacy and prepared by the Reference Materials Unit of the IRMM for this exercise. Sixty-six laboratories from 23 countries registered to the exercise and 61 of them reported results. Each participant received one bottle containing approximately 15 g of test material. Participants were asked to quantify the measurands in the powder and in the reconstituted formula. Reference values independent from the participants' results were established using isotope dilution inductively coupled plasma mass spectrometry. The total Cd mass fraction was determined by IRMM and LGC Ltd (UK), while the total Pb was determined by IRMM. The standard deviation for proficiency assessment σ^ was set at 22% of the assigned value for all measurands. Laboratories were rated with z- and ζ- (zeta) scores in accordance with ISO 13528. The outcome of this exercise is clearly influenced by the very low level of Cd and Pb content in the test material which triggered: a high number of 'less than' values; overestimated values especially for Pb very likely due to contamination; and a visible method influence in the case of Pb (methods based on atomic absorption were not sensitive enough to attain such low limits of detection). The results were also evaluated with regard to the reported limit of detection and some incoherencies were observed.

Interfacial behavior of common food contact polymer additives.

Irganox 1076 (IN1076) and Irganox 1010 (IN1010), phenol containing species often used as antioxidant additives in food packaging polymers have both hydrophilic and hydrophobic functional groups. Consequently these additives are likely to absorb to surfaces where their free energy is minimized. Experiments described in this work examine the two-dimensional phase behavior and vibrational structure of IN1076 and IN1010 films adsorbed to the air/water interface. Surface pressure isotherms show that repeated compression of these films leads to continued irreversible loss of molecules and that on a per molecule basis, this loss is more pronounced for IN1076 than for IN1010. Differences in the surface properties of these two antioxidant additives are interpreted based on differences in molecular structure. Surface specific vibrational measurements of these organic films show very little conformational order, implying that even when closely packed, both antioxidant species have little affinity for forming highly organized domains. These findings have important ramifications for mechanisms that reduce antioxidant activity in polymers as well as descriptions of antioxidant blooming on polymer surfaces.