T.C.
TARIM ve KÖYİŞLERİ BAKANLIĞI
Koruma ve Kontrol Genel Müdürlüğü
Communiqué on Method of Analysis for the Amount of Vinyl Chloride Monomer
in Articles and Materials 
Authorization Law: Turkish Food Codex
The Official Gazette: 22.03.2002-24703
Communication No : 2002/22
Objective
Article 1. The objective of this Communiqué is to determine the method of analysis to be used for the determination of the amount of vinyl chloride monomer in the articles and materials which come into contact with foodstuffs.
Scope
Article 2. This Communiqué covers the method of analysis to be used for the determination of the amount of vinyl chloride monomer in articles and materials.
Legal basis
Article 3. This Communiqué has been prepared in accordance with the Turkish Food Codex Regulation published in Official Gazette, dated 16.11.1997, reiterated no.23172.
Method of analysis
Article 4. The amount of vinyl chloride monomer in articles and materials is determined, according to Annex 1, by means of gas chromatography using the headspace method after dissolution or suspension of the sample in N,N-dimethyl acetamid.
Compliance with European Union
Article 5. This Communiqué has been prepared within the framework of compliance with European Union having regard to the Commission Directive 80/766/EEC for “ official contol of the vinyl chloride monomer level in materials and articles which are intented to come into contact with foodstuffs”. This Communiqué does not embarrass the laboratories from using the methods experienced according to their own legislation and having scientific validity. This Communiqué is applied compulsorily for the relations with European Union.
Provisional Article 1. The laboratories which are presently active and which use the methods of analysis included in this Communiqué must comply with the provisions of this Communiqué within 2 years.
Enforcement
Article 6. This Communiqué enters into force on the date of publication.
Execution
Article 7. The provisions of this Communiqué are executed by the Minister of Health and the Minister of Agriculture and Rural Affairs.
ANNEX- 1
Determination of the Amount of Vinyl Chloride Monomer in Materials and Articles
1. Scope and Field of Application
This method determines the amount of vinyl chloride monomer in articles and materials.
2. Principle
The amount of vinyl chloride monomer in articles and materials is determined by means of gas chromatography using the headspace method after dissolution or suspension of the sample in N,N-dimethylacetamide.
3. Reactives
3.1. Vinyl Chloride, its purity should be at least 99.5% in volumetric basis.
3.2. N.N-dimethyl acetamide, DMA; shall not contain any impurity having the same retention time under the conditions of the test either with the internal standard mentioned in 3.3. or with vinyl chloride.
3.3. Internal standard: Diethyl ether or cis-2-butene in DMA, these internal standards; must not contain any impurity having the same retention time with vinyl chloride under the conditions of the test.
4. Apparatus
Descriptions; “an instrument or piece of apparatus” are only mentioned for equipment or parts of equipment having a special condition.
4.1. Gas chromatograph (GC); fitted with automatic head-space sampler or with facilities for manual sample injection.
4.2. Flame ionization detector or other detectors mentioned in point 7,
4.3. Gas chromatographic column; must provide to separate the peaks of air of vinyl chloride and of internal standard, if used.
Furthermore, the combined 4.2. and 4.3. system must provide the signal obtained with a solution containing 0.02 mg vinyl chloride/L DMA or 0.002 mg vinyl chloride/kg DMA to be at least five times the background noise.
4.4. Sample phials or flasks should have silicon or butyl rubber septa.
When using manual sampling techniques, teh taking of a sample from headspace with a injector may cause a vacuum in the phial or flask. For this reason, the use of phials is recommended for manual sampling in cases of the phial is not pressurized before sampling.
4.5. Micro injector
4.6. The injector should have the gas impermeability for manual sampling.
4.7. Analytical balance should have the accuracy level of 0.1 mg.
5. Procedure
Vinyl chloride is a hazardous material and a gas at room temperature. For this reason, the solutions should be prepared on a well-ventilated fume cupboard.
All necessary precautions shall be taken to avoid any loss of vinyl chloride or DMA.
When applying manual sampling techniques, internal standart mentioned in 3.3 should be used.
When using an internal standard, the same solution must be utilized throughout the procedure.
5.1. Preparation of concentrated standard vinyl chloride solution at an approximately 2000 mg/kg:
A suitable glass vessel is weighed with an accuracy of 0.1 mg and a certain amount, i.e. 50 mL, DMA is added. It is re-weighed. A certain amount of, i.e. 0.1 g, vinyl chloride, either in gaseous or liquid form, is added by injecting slowly onto the DMA. Vinyl chloride may be added to DMA in bubbles of gas with an equipment preventing the loss of DMA. It is re-weighed with an accuracy of 0.1 mg. Two hours of waiting is required for having an equilibrium. The standard solution has to be kept in the refrigerator.
5.2. Preparation of dilute standard vinyl chloride solution
A weighed amount of concentrated standard vinyl chloride solution is taken and diluted to known volume or a known weight with DMA or internal standard solution. The concentration of the last dilute standard solution, Solution A, is expressed as mg/L or mg/kg respectively.
5.3. Preparation of the calibration curve.
The curve must comprise at least seven pairs of points.
Repeatability must be less than 0.02 mg vinyl chloride/L or kg DMA.
The regression line must be calculated with the following formula using the least squares techniques:
y = the height or area of peaks in any determination
x = the corresponding concentration on the regression line
n = number of determinations (n ? 14),
The curve must be linear. The results found by dividing the standard deviation of the concentrations calculated by the differences between the measured reactions, y, and the relevant concentrations calculated from the regretion curve over the average reaction value, ?, should not exceed 0.07.
yi= each individual measured response
zi= the corresponding value of the response, calculated from the regression line
(n ? 14),
Minimum seven phials (4.4) are prepared as two series. Dilute standard vinyl chloride solution (5.2.) DMA (3.2.) or internal standard solution in DMA (3.3.) is added to each phial such that a final vinyl chloride concentration in the duplicate solutions to be approximately 0, 0.050, 0.075, 0.100, 0.125, 0.150, 0.200 mg/L or mg/kg DMA. All phials should contain the same total volume of solution. Phials are sealed and the procedures mentioned in 5.6. are applied. A graphic is plotted in which the ordinate values are indicating the areas or heights of the vinyl chloride peaks of the duplicate solutions or relevant internal standard peaks in parallel solutions and basis values are the vinyl chloride concentrations in parallel solutions.
5.4. Validation of the standard solution obtained in 5.1. and 5.2.
The method explained in 5.1. and 5.2. is repeated in order to obtain a second diluted standard solution having a concentration of 0.01 mg vinyl chloride/L or 0.1 mg vinyl chloride/kg DMA or equal to the internal standard solution. The average of two gas chromatographic determinations of this solution must not differ by more than 5% from the corresponding point of the calibration curve. If the difference is more than 5%, the solutions defined in 5.1., 5.2., 5.3. and 5.4. are not accepted and the procedure is repeated from the beginning.
5.5. Preparation of the samples of articles and materials
Two phials are prepared. The sample obtained from a single article and material, divided into small pieces, is weighed into phials to be not less than 200 mg with an accuracy of 0.1 mg. The weighed quantity into each phial should be equal. The phial is immediately closed. 10 mL or 10 g of DMA or 10 mL or 10 g internal standard solution is added for each gram of sample to each phial. Phials are sealed and the procedure explained in 5.6. is applied.
5.6. Procedures applied in gas chromatography
5.6.1. Phials are agitated in order to obtain a sample solution or suspension homogeneous as as possible without letting the liquid and the septum.
5.6.2. All the sealed phials are put in a water bath at 60±1°C for two hours in order to have the equilibrium. They are agitated again, if necessary.
5.6.3. A sample is taken from the headspace of the phial. When using manual sampling techniques, hand skill must be exercised for reproducible sampling. Injector must be pre-heated to the temperature of the sample. The areas or heights of the peaks of vinyl chloride and if used internal standard are measured.
5.6.4. The excess DMA in the column is removed by an appropriate method as soon as the DMA peaks are observed on the chromatogram.
6. Calculation of the Results
6.1. The unknown concentration of both of two samples in the solution is found interpolation on the curve if internal standard is used. The amount of vinyl chloride in both of two samples is calculated with the following formula.
X: Concentration of vinyl chloride in the article and material, mg/kg
C: Concentration of vinyl chloride in the phial containing the sample of article and material, mg/L or mg/kg
V: Volume or mass of DMA in the phial containing the sample of article and material, L or kg
M: amount of the sample of article and material, g
6.2. The concentration of vinyl chloride in the articles and materials under investigation, is given in mg/kg as the average of two concentrations of vinyl chloride determined in 6.1 if the repeatability criterion in 8 is satisfied.
strong>7. Confirmation of Amount of Vinyl Chloride
If the amount of vinyl chloride in the articles and materials calculated under point 6.2, exceeds the maximum permissible amount the results obtained by the analysis of both of two samples must be confirmed in one of three ways given below:
a) At least, another column (4.3.) with a stationary phase and different polarity can be used. This procedure is carried out until a chromatogram having non coinciding peaks of the vinyl chloride and/or internal standard with the components of sample of article and material.
b) Other detectors like the micro – electrolytic conductivity detector can be used.
c) Mass spectrophotometry can be used. In this case, the presence of molecular ions, having main masses (mass/ion) 62 and 64 with a ratio of 3:1, is an indicator of the presence of vinyl chloride with a high possibility. In case of doubt, the total mass spectrum must be checked.
8. Repeatability
The difference between two determinations carried out under the same conditions, by the same analyst, simultaneously or rapidly one after the other on the same sample, according to 6.1. must not exceed 0.2 mg of vinyl chloride per kg of article and material.