Does home cooking have an effect on phthalate levels in food?

A

Instability of the DNPH-formaldehyde derivative in the certified reference material BCR-551 stored at -70 °C but not at -20 °C

During the post-certification stability monitoring of the certified reference material (CRM) BCR-551 (DNPHderivatives dissolved in acetonitrile), a decreased concentration of one of the analytes of this CRM, formaldehyde DNPH-derivative, was detected in reference samples (stored at -70 °C) while normal "on sale" samples (stored at -20 °C) remained stable. This behaviour is contrary to the expectation of better stability at lower temperatures. Apparently, the formaldehyde DNPH-derivative reacts with dinitrophenylhydrazine (DNPH) left-over from the synthesis phase, to produce two new substances. These substances have been elucidated as C13H12N8O8 (substance 1) and C20H16N12O12 (substance 2) which, based on their structure, are suggested to be produced consecutively: DNPH + formaldehyde DNPH-derivative -> substance 1 substance 1 + formaldehyde DNPH-derivative -> substance 2 Since acetonitrile freezes at -45 °C, reference samples are frozen at -70 °C while normal samples are still liquid at -20 °C. We believe that this leads to a cryo-concentration of the solutes above the eutectic point and thus to an increased reaction rate in the reference samples. This case demonstrates that care should be taken when extrapolating stability results towards conditions that never have been tested, especially if phase transitions are involved, even at temperature as low as -70 °C. Furthermore, a slower degradation rate at lower temperatures can be overcompensated by a higher concentration due to cryo-concentration above the eutectic temperature.JRC.D.2-Standards for Innovation and sustainable Developmen

Survey of phthalate levels in food on the Belgian market and their possible contamination pathways

The main pathway for human exposure to phthalates is via dietary intake. The presence of phthalates in food is not only because of their movement up the food-chain, but also due to their migration from food packaging into food. In this study, the presence and concentration of phthalates levels in food products on the Belgian market were determined and the various contamination pathways were explored. For this purpose, a sampling campaign and analytical measurements in the laboratory were carried out. Four hundred representative samples of widely consumed foods were purchased in Belgian shops. Sample selection is based on 1) consumption data from the Belgian national food consumption survey and 2) the likelihood that foods contain phthalates. Brand name, packaging material and properties, fat content, date of production or shelf life, time and place of purchase, picture and product specific properties (e.g. pH, preserving agent) were stored in a database. This database was further used to explore the various contamination pathways by identifying relations between measured phthalate concentrations and sample properties. The measurement campaign involves 10 phthalate esters which are determined by GC-EI-MS. Blank concentrations were carefully controlled because phthalates are omnipresent in the laboratory. We developed suitable extraction techniques for the various food matrices. The analysis of food samples on the Belgian market shows a wide variety of phthalate concentrations. Possible contamination causing conditions are e.g. the pH and fat content of the food product and the composition and the properties of the packaging material. Acknowledgement – This study was funded by the Federal Public Service of Health, Food Chain Safety and Environment (contract RT/ 08/1 PHTAL