BASIC RULES FOR DETERMINING THE MIGRATION OF LEAD AND CADMIUM
1. Test liquid ('simulant')
4 % (v/v) acetic acid, in a freshly prepared aqueous solution.
2. Test conditions
2.1. Carry out the test at a temperature of 22 ± 2 °C for a duration of 24 ± 0,5 hours.
2.2. When the migration of lead is to be determined, cover the sample by an appropriate means of protection and expose it to the usual lighting conditions in a laboratory.
When the migration of cadmium or of lead and cadmium is to be determined, cover the sample so as to ensure that the surface to be tested is kept in total darkness.
3. Filling
3.1. Samples which can be filled
Fill the article with a 4 % (v/v) acetic acid solution to a level no more than 1 mm from the overflow point; the distance is measured from the upper rim of the sample.
Samples with a flat or slightly sloping rim should be filled so that the distance between the surface of the liquid and the overflow point is no more than 6 mm measured along the sloping rim.
3.2. Samples which cannot be filled
The surface of the sample which is not intended to come into contact with foodstuffs is first covered with a suitable protective layer able to resist the action of the 4 % (v/v) acetic acid solution. The sample is then immersed in a recipient containing a known volume of acetic acid solution in such a way that the surface intended to come into contact with foodstuffs is completely covered by the test liquid.
4. Determination of the surface area
The surface area of the articles in category 1 is equal to the surface area of the meniscus formed by the free liquid surface obtained by complying with the filling requirements set out in section 3 above.
ANNEX II
METHODS OF ANALYSIS FOR DETERMINING THE MIGRATION OF LEAD AND CADMIUM
1. Object and field of application
The method allows the specific migration of lead and/or cadmium to be determined.
2. Principle
The determination of the specific migration of lead and/or cadmium is carried out by atomic absorption spectrophotometry.
3. Reagents
- All reagents must be of analytical quality, unless otherwise specified.
- Where reference is made to water, this always means distilled water or water of equivalent quality.
3.1. 4 % (v/v) acetic acid, in aqueous solution
Add 40 ml of glacial acetic acid to water and make up to 1 000 ml.
3.2. Stock solutions
Prepare stock solutions containing 1 000 mg/litre of lead and at least 500 mg/litre of cadmium respectively in a 4 % acetic acid solution (3.1).
4. Instruments
4.1. Atomic absorption spectrophotometer
The instrument's detection limit for lead and cadmium must be equal to or lower than:
- 0,1 mg/litre for lead,
- 0,01 mg/litre for cadmium.
The detection limit is defined as the concentration of the element in 4 % acetic acid (3.1) which gives a signal equal to twice the background noise of the instrument.
5. Method
5.1. Preparation of the sample
The sample must be clean and free from grease or other matter likely to affect the test.
Wash the sample in a solution containing a household liquid detergent at a temperature of approximately 40 °C. Rinse the sample first in tapwater and then in distilled water or water of equivalent quality. Drain and dry so as to avoid any stain. The surface to be tested should not be handled after it has been cleaned.
5.2. Determination of lead and/or cadmium
- The sample thus prepared is tested under the conditions laid down in Annex I.
- Before taking the test solution for determining lead and/or cadmium, homogenize the content of the sample by an appropriate method which avoids any loss of solution or abrasion of the surface being tested.
- Carry out a blank test on the reagent used for each series of determinations.
- Carry out determinations for lead and/or cadmium under appropriate conditions by atomic absorption spectrophotometry.