1991 Volume 32 Issue 3 Pages 168-176_1
Methods for determining low concentrations of lead and cadmium leached into 4% acetic acid from ceramicware were studied. The limit of leachable lead proposed for ceramic pitchers by the Food and Drug Administration, U. S. A., 0.1ppm in the extraction solution, could be determined by flame-atomic absorption spectrometry at 217.0nm. Using a 10-fold-concentrated extraction solution, we recovered 95.7±6.7% of added lead with a 7.0% coefficient of variation. Release of lead from four pitchers purchased at a department store in Tokyo was between 0.008 and 0.01ppm when the migration test was carried out with 4% acetic acid at 19±3°C for 24hr. Lead was also determined by a flameless method, as these concentrations were lower than the detection limit of the flame method even when the extraction solution was concentrated 10-fold. Cadmium, the release of which is also regulated by the Food Sanitation Law, was not detectable, i. e., if present, its content was less than 0.0005ppm in the extraction solution.
Some other dishes which release lead and cadmium were used in place of the pitchers to determine the migration behavior of these metals from other ceramicware. The relation of the release of these metals to extraction time was biexponential when 4% acetic acid or grapefruit juice was used as an extraction solvent, when 4% acetic acid was used for seven days or was changed every 24hr, and when the dishes were kept at 5°C or at room temperature (24±4°C). Some other metals in the extraction solution were determined by ICP-atomic emission spectrometry.
