Commission Regulation (EU) No 252/2012 of 21 March 2012 laying down methods of sampling and analysis for the official control of levels of dioxins, dioxin-like PCBs and non-dioxin-like PCBs in certain foodstuffs and repealing Regulation (EC) No 1883/2006 Text with EEA relevance
1.1. "Action level" means the level of a given substance, as laid down in Annex to Recommendation 2011/516/EU, which triggers investigations to identify the source of that substance in cases where increased levels of the substance are detected. 1.2. "Bioanalytical methods" means methods based on the use of biological principles like cell-based assays, receptor-assays or immunoassays. They do not give results at the congener level but merely an indication Bioanalytical methods are not specific to those congeners included in the TEF-scheme. Other structurally related AhR-active compounds may be present in the sample extract which contribute to the overall response. Therefore, bioanalytical results cannot be an estimate but rather an indication of the TEQ level in the sample. 1.3. "Bioassay apparent recovery" means the BEQ level calculated from the TCDD or PCB 126 calibration curve corrected for the blank and then divided by the GC/HRMS determined TEQ level. It attempts to correct factors like the loss of PCDD/PCDFs and dioxin-like compounds during the extraction and clean-up steps, co-extracted compounds increasing or decreasing the response (agonistic and antagonistic effects), the quality of the curve fit, or differences between the TEF and the REP values. The bioassay apparent recovery is calculated from suitable reference samples with representative congener patterns around the level of interest. 1.4. "Semi-quantitative methods" means methods which give an approximate indication of the concentration of the putative analyte, while the numerical result does not meet the requirements for quantitative methods. 1.5. "The accepted specific limit of quantification of an individual congener" means the concentration of an analyte in the extract of a sample which produces an instrumental response at two different ions to be monitored with an S/N (signal/noise) ratio of 3:1 for the less intensive signal and fulfilment of identification criteria as described, for example, in standard prEN 16215 (Animal feed — Determination of dioxins and dioxin-like PCBs by GC/HRMS and of indicator PCBs by GC/HRMS) and/or in EPA method 1613 revision B. 1.6. "Upper-bound" means the concept which requires using the limit of quantification for the contribution of each non-quantified congener. 1.7. "Lower-bound" means the concept which requires using zero for the contribution of each non-quantified congener. 1.8. "Medium-bound" means the concept which requires using half of the limit of quantification calculating the contribution of each non-quantified congener. 1.9. "Lot" means an identifiable quantity of food delivered at one time and determined by the official to have common characteristics, such as origin, variety, type of packing, packer, consignor or markings. In the case of fish and fishery products, also the size of fish shall be comparable. In case the size and/or weight of the fish is not comparable within a consignment, the consignment may still be considered as a lot but a specific sampling procedure has to be applied. 1.10. "Sublot" means designated part of a large lot in order to apply the sampling method on that designated part. Each sublot must be physically separated and identifiable. 1.11. "Incremental sample" means a quantity of material taken from a single place in the lot or sublot. 1.12. "Aggregate sample" means the combined total of all the incremental samples taken from the lot or sublot. 1.13. "Laboratory sample" means a representative part/quantity of the aggregate sample intended for the laboratory.
| Lot weight (ton) | Weight or number of sublots |
|---|---|
| ≥ | 500 tonnes |
| > 300 and < | 3 sublots |
| ≥ 50 and ≤ 300 | 100 tonnes |
| < 50 | — |
| Lot weight (ton) | Weight or number of sublots |
|---|---|
| ≥ 15 | 15-30 tonnes |
| < 15 | — |
| Weight or volume of lot/sublot (in kg or litre) | Minimum number of incremental samples to be taken |
|---|---|
| < 50 | |
| 50 to 500 | |
| > 500 |
| Number of packages or units in the lot/sublot | Number of packages or units to be taken |
|---|---|
| 1 to 25 | at least 1 package or unit |
| 26 to 100 | about 5 %, at least 2 packages or units |
| > 100 | about 5 %, at maximum 10 packages or units |
In case the lot to be sampled contains small fishes (individual fishes weighing < about 1 kg), the whole fish is taken as incremental sample to form the aggregate sample. In case the resulting aggregate sample weighs more than 3 kg, the incremental samples may consist of the middle part, weighing each at least 100 grams, of the fishes forming the aggregate sample. The whole part to which the maximum level is applicable is used for homogenisation of the sample. The middle part of the fish is where the centre of gravity is. This is located in most cases at the dorsal fin (in case the fish has a dorsal fin) or halfway between the gill opening and the anus. In case the lot to be sampled contains larger fishes (individual fishes weighing more than about 1 kg), the incremental sample consists of the middle part of the fish. Each incremental sample weighs at least 100 grams. For fishes of intermediate size (about 1-6 kg) the incremental sample is taken as a slice of the fish from backbone to belly in the middle part of the fish. For very large fishes (e.g. > about 6 kg), the incremental part is taken from the right side (frontal view) dorso-lateral muscle meat in the middle part of the fish In case the taking of such a piece of the middle part of the fish would result in a significant economic damage, taking of three incremental samples of at least 350 grams each may be considered as being sufficient, independently of the size of the lot or alternatively an equal part of the muscled meat close to the tail part and the muscle meat close to the head part of one fish may be taken to form the incremental sample being representative for the level of dioxins in the whole fish.
The provisions of point III.3 as regards sample constitution shall apply. In case a size or weight class/category is predominant (about 80 % or more of the lot), the sample is taken from fishes with the predominant size or weight. This sample is to be considered as being representative for the whole lot. In case no particular size or weight class/category predominates, then it must be ensured that the fishes selected for the sample are representative for the lot. Specific guidance for such cases is provided in "Guidance on sampling of whole fishes of different size and/or weight" http://ec.europa.eu/food/food/chemicalsafety/contaminants/dioxins_en.htm
by calculating the expanded uncertainty, using a coverage factor of 2 which gives a level of confidence of approximately 95 %. A lot or sublot is non-compliant if the measured value minus U is above the established permitted level, by establishing the decision limit (CCα) according to the provisions of Decision 2002/657/EC (point 3.1.2.5 of Annex I to that Decision — the case of substances with an established permitted level). A lot or sublot is non-compliant if the measured value is equal to or above the CCα.
performed by a screening method with a false-compliant rate below 5 % indicates that the level does not exceed the respective maximum level of PCDD/Fs and the sum of PCDD/Fs and dioxin-like PCBs as laid down in Regulation (EC) No 1881/2006, performed by a confirmatory method does not exceed the respective maximum level of PCDD/Fs and the sum of PCDD/Fs and dioxin-like PCBs as laid down in Regulation (EC) No 1881/2006 taking into account the measurement uncertainty.
by calculating the expanded uncertainty, using a coverage factor of 2 which gives a level of confidence of approximately 95 %. A lot or sublot is non-compliant if the measured value minus U is above the established permitted level. In case of a separate determination of PCDD/Fs and dioxin-like-PCBs the sum of the estimated expanded uncertainty of the separate analytical results of PCDD/Fs and dioxin-like PCBs has to be used for the estimated expanded uncertainty of the sum of PCDD/Fs and dioxin-like PCBs, by establishing the decision limit (CCα) according to the provisions of Decision 2002/657/EC (point 3.1.2.5 of Annex I to that Decision — the case of substances with established permitted level) a lot or sublot is non-compliant if the measured value is equal to or above the CCα.
(a) selection of those samples with levels of PCDD/Fs and dioxin-like PCBs that exceed the maximum levels, or the action levels. This approach may involve a screening method allowing cost-effective high sample-throughput, thus increasing the chance to discover new incidents with high exposure and health risks of consumers. Screening methods may comprise bioanalytical methods and GC/MS methods. Their application should aim at avoiding false-compliant results. The concentration of PCDD/Fs and the sum of PCDD/Fs and dioxin-like PCBs in those samples with significant levels needs to be determined/confirmed by a confirmatory method; (b) determination of the levels of PCDD/Fs and dioxin-like PCBs in food samples in the range of low background levels. This is important in order to follow time trends, exposure assessment of the population and to build a database for possible re-evaluation of action and maximum levels. This goal is achieved by confirmatory methods enabling the PCDD/Fs and dioxin-like PCBs to be identified and quantified unequivocally at the level of interest. These methods can be used for confirmation of results obtained by screening methods and for determination of low background levels in food monitoring. They are also important for establishing congener patterns in order to identify the source of a possible contamination. At present such methods utilise high-resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS).
bioanalytical methods which are able to detect the analytes of interest, include a calibration curve, give a yes/no-decision for indication for the possible exceedance of the level of interest and allow to report the result as Bioanalytical Equivalents (BEQ), being an indication of the TEQ value in the sample, physico-chemical test (e.g. GC-MS/MS or GC/LRMS) where the measured method precision characteristics do not meet the requirements for quantitative tests.
Measures must be taken to avoid cross-contamination at each stage of the sampling and analysis procedure. The samples must be stored and transported in glass, aluminium, polypropylene or polyethylene containers suitable for storage without any influence on the levels of PCDD/Fs and dioxin-like PCBs in the samples. Traces of paper dust must be removed from the sample container. The sample storage and transportation has to be performed in a way that maintains the integrity of the foodstuff sample. In so far as relevant, finely grind and mix thoroughly each laboratory sample using a process that has been demonstrated to achieve complete homogenisation (e.g. ground to pass a 1 mm sieve); samples have to be dried before grinding if moisture content is too high. Control of reagents, glassware and equipment for possible influence of TEQ- or BEQ-based results is of general importance. A blank analysis shall be performed by carrying out the entire analytical procedure omitting only the sample. For bioanalytical methods, it is of great importance that all glassware and solvents used in analysis shall be tested to be free of compounds that interfere with the detection of target compounds in the working range. Glassware shall be rinsed with solvents or/and heated at temperatures suitable to remove traces of PCDD/Fs, dioxin-like compounds and interfering compounds from its surface. Sample quantity used for the extraction must be sufficient to fulfil the requirements with respect to a sufficiently low working range including the concentrations of interest. The specific sample preparation procedures used for the products under consideration shall follow internationally accepted guidelines. In the case of fish, the skin has to be removed as the maximum level applies to muscle meat without skin. However it is necessary that all remaining muscle meat and fat tissue on the inner side of the skin are carefully and completely scraped off from the skin and added to the sample to be analysed.
In accordance with the provisions of Regulation (EC) No 882/2004, laboratories shall be accredited by a recognised body operating in accordance with ISO Guide 58 to ensure that they are applying analytical quality assurance. Laboratories shall be accredited following the EN ISO/IEC 17025 standard. Laboratory proficiency shall be proven by the continuous successful participation in interlaboratory studies for the determination of PCDD/Fs and dioxin-like PCBs in relevant food matrices and concentration ranges. Laboratories applying screening methods for routine control of samples shall establish a close cooperation with laboratories applying the confirmatory method, both for quality control and confirmation of the analytical result of suspected samples.
For PCDD/Fs, detectable quantities have to be in the upper femtogram (10 –15 g) range because of extreme toxicity of some of these compounds. For most PCB congeners limit of quantification in the nanogram (10–9 g) range is already sufficient. However, for the measurement of the more toxic dioxin-like PCB congeners (in particular non-ortho substituted congeners) the lower end of the working range must reach the low picogram (10–12 g) levels.
A distinction is required between PCDD/Fs and dioxin-like PCBs and a multitude of other, coextracted and possibly interfering compounds present at concentrations up to several orders of magnitude higher than those of the analytes of interest. For gas chromatography/mass spectrometry (GC/MS) methods, a differentiation among various congeners is necessary, such as between toxic (e.g. the 17 2,3,7,8-substituted PCDD/Fs, and 12 dioxin-like PCBs) and other congeners. Bioanalytical methods shall be able to detect the target compounds as the sum of PCDD/Fs, and/or dioxin-like PCBs. Sample clean-up shall aim at removing compounds causing false-non-compliant results or compounds that may decrease the response, causing false-compliant results.
For GC/MS methods, the determination shall provide a valid estimate of the true concentration in a sample. High accuracy (accuracy of the measurement: the closeness of the agreement between the result of a measurement with the true or assigned value of the measurand) is necessary to avoid the rejection of a sample analysis result on the basis of poor reliability of the determined TEQ level. Accuracy is expressed as "trueness" (difference between the mean value measured for an analyte in a certified material and its certified value, expressed as percentage of this value) and "precision" (RSD R relative standard deviation calculated from results generated under reproducibility conditions).For bioanalytical methods, the bioassay apparent recovery shall be determined.
Laboratories shall demonstrate the performance of a method in the range of the level of interest, e.g. 0,5 ×, 1 × and 2 × the level of interest with an acceptable coefficient of variation for repeated analysis, during the validation procedure and/or during routine analysis. Regular blank controls and spiking experiments or analysis of control samples (preferably, if available, certified reference material) shall be performed as internal quality control measures. Quality control (QC) charts for blank controls, spiking experiments or analysis of control samples shall be recorded and checked to make sure the analytical performance is in accordance with the requirements.
For a bioanalytical screening method, establishment of the LOQ is not an indispensable requirement but the method shall prove that it can differentiate between the blank and the cut-off value. When providing a BEQ-level, a reporting level shall be established to deal with samples showing a response below this level. The reporting level shall be demonstrated to be different from procedure blank samples at least by a factor of three, with a response below the working range. It shall therefore be calculated from samples containing the target compounds around the required minimum level, and not from a S/N ratio or an assay blank. Limit of quantification (LOQ) for a confirmatory method shall be about one fifth of the level of interest.
For reliable results from confirmatory or screening methods, the following criteria must be met for the TEQ value respectively the BEQ value, whether determined as total TEQ (as sum of PCDD/F and dioxin-like PCBs) or separately for PCDD/F and dioxin-like PCBs. with respect to the maximum levels Screening with bioanalytical or physico-chemical methods Confirmatory methods False-compliant rate < 5 % Trueness – 20 % to + 20 % Repeatability (RSD r )< 20 % Within-laboratory reproducibility (RSD R )< 25 % < 15 %
Both GC/MS and bioanalytical methods may be used for screening. For GC/MS methods the requirements as laid down in point 7 of this Annex are to be used. For cell based bioanalytical methods specific requirements are laid down in point 8 of this Annex. Laboratories applying screening methods for routine control of samples shall establish a close cooperation with laboratories applying the confirmatory method. Performance verification of the screening method is required during routine analysis, by analytical quality control and on-going method validation. There must be a continuous programme for control of compliant results. Check on possible suppression of the cell response and cytotoxicity 20 % of the sample extracts shall be measured in routine screening without and with 2,3,7,8-TCDD added corresponding to the level of interest, to check if the response is possibly suppressed by interfering substances present in the sample extract. The measured concentration of the spiked sample is compared to the sum of the concentration of the unspiked extract plus the spiking concentration. If this measured concentration is more than 25 % lower than the calculated (sum) concentration, this is an indication of a potential signal suppression and the respective sample must be submitted to GC/HRMS confirmatory analysis. Results shall be monitored in quality control charts. Quality control on compliant samples Approximately 2 to 10 % of the compliant samples, depending on sample matrix and laboratory experience, shall be confirmed by GC/HRMS. Determination of false-compliant rates from QC data The rate of false-compliant results from screening of samples below and above the maximum level or the action level shall be determined. Actual false-compliant rates shall be below 5 %. After a minimum of 20 confirmed results per matrix/matrix group is available from the quality control of compliant samples, conclusions on the false-compliant rate shall be drawn from this database. The results from samples analysed in ring trials or during contamination incidents, covering a concentration range up to, e.g. 2 × the maximum level (ML), may also be included in the minimum of 20 results for evaluation of the false-compliant rate. The samples shall cover most frequent congener patterns, representing various sources. Although screening assays shall preferentially aim at detecting samples exceeding the action level, the criterion for determining false-compliant rates is the maximum level, taking into account the measurement uncertainty of the confirmatory method. Potential non-compliant results from screening shall always be verified by a confirmatory method of analysis (GC/HRMS). These samples may also be used to evaluate the rate of false-non-compliant results. For screening methods, the rate of "false-non-compliant results" is the fraction of results confirmed to be compliant from GC/HRMS confirmatory analysis, while in previous screening the sample had been declared to be suspected to be non-compliant. However, evaluation of the advantageousness of the screening method shall be based on comparison of false-non-compliant samples with the total number of samples checked. This rate shall be low enough to make the use of a screening tool advantageous. At least under validation conditions, bioanalytical methods shall provide a valid indication of the TEQ level, calculated and expressed as BEQ. Also for bioanalytical methods carried out under repeatability conditions, the intra-laboratory RSD r would typically be smaller than the reproducibility RSDR .
The difference between upper-bound level and lower bound level shall not exceed 20 % for foodstuffs with a contamination of about 1 pg WHO-TEQ/g fat (based on the sum of PCDD/Fs and dioxin-like PCBs). For foodstuffs with a low fat content, the same requirements for contamination levels of about 1 pg WHO-TEQ/g product have to be applied. For lower contamination levels, for example 0,5 pg WHO-TEQ/g product, the difference between upper-bound and lowerbound level may be in the range of 25 % to 40 %.
Addition of 13 C-labelled 2,3,7,8-chlorine substituted internal PCDD/F standards and of13 C-labelled internal dioxin-like PCB standards must be carried out at the very beginning of the analytical method, e.g. prior to extraction in order to validate the analytical procedure. At least one congener for each of the tetra- to octa-chlorinated homologous groups for PCDD/Fs and at least one congener for each of the homologous groups for dioxin-like PCBs must be added (alternatively, at least one congener for each mass spectrometric selected ion recording function used for monitoring PCDD/Fs and dioxin-like PCBs). In case of confirmatory methods, all 1713 C-labelled 2,3,7,8-substituted internal PCDD/F standards and all 1213 C-labelled internal dioxin-like PCB standards shall be used.Relative response factors shall also be determined for those congeners for which no 13 C-labelled analogue is added by using appropriate calibration solutions.For foodstuffs of plant origin and foodstuffs of animal origin containing less than 10 % fat, the addition of the internal standards is mandatory prior to extraction. For foodstuffs of animal origin containing more than 10 % fat, the internal standards may be added either before or after fat extraction. An appropriate validation of the extraction efficiency shall be carried out, depending on the stage at which internal standards are introduced and on whether results are reported on product or fat basis. Prior to GC/MS analysis, 1 or 2 recovery (surrogate) standard(s) must be added. Control of recovery is necessary. For confirmatory methods, the recoveries of the individual internal standards shall be in the range of 60 to 120 %. Lower or higher recoveries for individual congeners, in particular for some hepta- and octa- chlorinated dibenzo-p-dioxins and dibenzofurans, are acceptable on the condition that their contribution to the TEQ value does not exceed 10 % of the total TEQ value (based on sum of PCDD/F and dioxin-like PCBs). For GC/MS screening methods, the recoveries shall be in the range of 30 to 140 %.
Separation of PCDD/Fs from interfering chlorinated compounds such as non-dioxin-like PCBs and chlorinated diphenyl ethers shall be carried out by suitable chromatographic techniques (preferably with a florisil, alumina and/or carbon column). Gas-chromatographic separation of isomers shall be sufficient (< 25 % peak to peak between 1,2,3,4,7,8-HxCDF and 1,2,3,6,7,8-HxCDF).
The range of the calibration curve shall cover the relevant range of levels of interest.
When calculating the concentrations from a TCDD calibration curve, values at the lower and higher end of the curve will show a high variation (high coefficient of variation (CV)). The working range is the area where this CV is smaller than 15 %. The lower end of the working range (reporting limit) must further be set significantly (at least by a factor of three) above the procedure blanks. The upper end of the working range is usually represented by the EC 70 value (70 % of maximal effective concentration), but lower if the CV is higher than 15 % in this range. The working range shall be established during validation. Cut-off values (8.3) must be well within the working range.Standard solutions and sample extracts shall be tested at least in duplicate. When using duplicates, a standard solution or a control extract tested in 4 to 6 wells divided over the plate shall produce a response or concentration (only possible in the working range) based on a CV < 15 %.
Levels in samples may be estimated by comparison of the test response with a calibration curve of TCDD (or PCB 126 or a PCDD/F/dioxin-like PCB standard mixture) to calculate the BEQ level in the extract and subsequently in the sample. Calibration curves shall contain 8 to 12 concentrations (at least in duplicates), with enough concentrations in the lower part of the curve (working range). Special attention shall be paid to the quality of the curve-fit in the working range. As such, the R 2 value is of little or no value in estimating the goodness of fit in non-linear regression. A better fit will be achieved by minimising the difference between calculated and observed levels in the working range of the curve (e.g. by minimising the sum of squared residuals).The estimated level in the sample extract is subsequently corrected for the BEQ level calculated for a matrix/solvent blank sample (to account for impurities from solvents and chemicals used), and the apparent recovery (calculated from the BEQ level of suitable reference samples with representative congener patterns around the level of interest). For performing a recovery correction, the apparent recovery must always be within the required range (see point 8.1.4). Reference samples used for recovery correction must comply with requirements as given in point 8.2.
The loss of compounds during the clean-up shall be checked during validation. A blank sample spiked with a mixture of the different congeners shall be submitted to clean-up (at least n = 3) and the recovery and variability checked by GC/HRMS analysis. The recovery shall be within 60 to 120 % especially for congeners contributing more than 10 % to the TEQ-level in various mixtures.
When reporting BEQ levels, a reporting limit shall be determined from relevant matrix samples involving typical congener patterns, but not from the calibration curve of the standards due to low precision in the lower range of the curve. Effects from extraction and clean-up must be taken into account. The reporting limit must be set significantly (at least by a factor of three) above the procedure blanks.
Reference samples shall represent sample matrix, congener patterns and concentration ranges for PCDD/Fs and dioxin-like PCBs around the level of interest (maximum or action levels). A procedure blank, or preferably a matrix blank, and a reference sample at the level of interest have to be included in each test series. These samples must be extracted and tested at the same time under identical conditions. The reference sample must show a clearly elevated response in comparison to the blank sample, thus ensuring the suitability of the test. These samples may be used for blank and recovery corrections. Reference samples chosen for performing a recovery correction shall be representative for the test samples, meaning that congener patterns shall not lead to an underestimation of levels. Extra reference samples at, e.g. 0,5 × and 2 × the level of interest may be included to demonstrate the proper performance of the test in the range of interest for the control of the level of interest. Combined, these samples may be used for calculating the BEQ-levels in test samples (8.1.2.2).
square sum parameter, i = index for calibration point i
Since no internal standards can be used in bioanalytical methods, tests on repeatability shall be carried out to obtain information on the standard deviation within and between test series. Repeatability shall be below 20 %, intra-laboratory reproducibility below 25 %. This shall be based on the calculated levels in BEQs after blank and recovery correction. As part of the validation process, the test must be shown to discriminate between a blank sample and a level at the cut-off value, allowing the identification of samples above the corresponding cut-off value (see 8.1.2). Target compounds, possible interferences and maximum tolerable blank levels shall be defined. The percent standard deviation in the response or concentration calculated from the response (only possible in working range) of a triplicate determination of a sample extract shall not be above 15 %. The uncorrected results of the reference sample(s) expressed in BEQs (blank and level of interest) shall be used for evaluation of the performance of the bioanalytical method over a constant time period. Quality control (QC) charts for procedure blanks and each type of reference sample shall be recorded and checked to make sure the analytical performance is in accordance with the requirements, in particular for the procedure blanks with regard to the requested minimum difference to the lower end of the working range and for the reference samples with regard to within-laboratory reproducibility. Procedure blanks must be well controlled in order to avoid false-compliant results when subtracted. The results from the GC/HRMS analyses of suspected samples and 2 to 10 % of the compliant samples (minimum of 20 samples per matrix) shall be collected and used to evaluate the performance of the screening method and the relationship between BEQs and TEQs. This database might be used for re-evaluation of cut-off values applicable to routine samples for the validated matrices. Successful method performance may also be demonstrated by participation in ring trials. The results from samples analysed in ring trials, covering a concentration range up to, e.g. 2 × ML, may also be included in the evaluation of the false-compliant rate, if a laboratory is able to demonstrate its successful performance. The samples shall cover most frequent congener patterns, representing various sources. During incidents, the cut-off values may be re-evaluated, reflecting the specific matrix and congener patterns of this single incident.
In so far as the used analytical procedure makes it possible, the analytical results shall contain the levels of the individual PCDD/F and dioxin-like PCB congeners and be reported as lower-bound, upper-bound and medium-bound in order to include a maximum of information in the reporting of the results and thereby enabling the interpretation of the results according to specific requirements. The report shall also include the method used for extraction of PCDD/Fs, dioxin-like PCBs and lipids. The lipid content of the sample shall be determined and reported for food samples with maximum or action levels expressed on fat basis and an expected fat concentration in the range of 0-2 % (in correspondence to existing legislation), for other samples is the determination of the lipid content optional. The recoveries of the individual internal standards must be made available in case the recoveries are outside the range mentioned in point 7.2, in case the maximum level is exceeded and in other cases upon request. As the uncertainty of measurement is to be taken into account when deciding about the compliance of a sample, this parameter shall also be made available. Thus, analytical results shall be reported as x +/– U whereby x is the analytical result and U is the expanded measurement uncertainty using a coverage factor of 2 which gives a level of confidence of approximately 95 %. In case of a separate determination of PCDD/Fs and dioxin-like-PCBs the sum of the estimated expanded uncertainty of the separate analytical results of PCDD/Fs and dioxin-like PCBs has to be used for the sum of PCDD/Fs and dioxin-like PCBs. If the uncertainty of measurement is taken into account by applying CCα (as described in Annex II, point IV. 2), this parameter shall be reported. The results shall be expressed in the same units and with (at least) the same number of significant figures as the maximum levels laid down in Regulation (EC) No 1881/2006.
The result of the screening shall be expressed as compliant or suspected to be non-compliant ("suspected"). In addition, a result for PCDD/F and/or dioxin-like PCBs expressed in Bioanalytical Equivalents (BEQ) (not TEQ) may be given (see Annex III, point 2). If measurement uncertainty on the calculated BEQ-level is given, e.g. as standard deviation, it must be based on at least a triplicate analysis (including extraction, clean up and determination of the test response) of the sample. Samples with a response below the reporting limit shall be expressed as lower than the reporting limit. For each type of sample matrix, the report shall mention the level of interest (maximum level, action level) on which the evaluation is based. The report shall mention the type of test applied, the basic test principle and kind of calibration. The report shall also include the method used for extraction of PCDD/Fs, dioxin-like PCBs and lipids. The lipid content of the sample shall be determined and reported for food samples with maximum or action levels expressed on fat basis and an expected fat concentration in the range of 0-2 % (in correspondence to existing legislation), for other samples is the determination of the lipid content optional.
| Congener | TEF value |
|---|---|
| 2,3,7,8-TCDD | |
| 1,2,3,7,8-PeCDD | |
| 1,2,3,4,7,8-HxCDD | |
| 1,2,3,6,7,8-HxCDD | |
| 1,2,3,7,8,9-HxCDD | |
| 1,2,3,4,6,7,8-HpCDD | |
| OCDD | |
| 2,3,7,8-TCDF | |
| 1,2,3,7,8-PeCDF | |
| 2,3,4,7,8-PeCDF | |
| 1,2,3,4,7,8-HxCDF | |
| 1,2,3,6,7,8-HxCDF | |
| 1,2,3,7,8,9-HxCDF | |
| 2,3,4,6,7,8-HxCDF | |
| 1,2,3,4,6,7,8-HpCDF | |
| 1,2,3,4,7,8,9-HpCDF | |
| OCDF | |
| PCB 77 | |
| PCB 81 | |
| PCB 126 | |
| PCB 169 | |
| PCB 105 | |
| PCB 114 | |
| PCB 118 | |
| PCB 123 | |
| PCB 156 | |
| PCB 157 | |
| PCB 167 | |
| PCB 189 |
Relative retention time in relation to internal standards or reference standards (acceptable deviation of +/- 0,25 %). Gas chromatographic separation of all six indicator PCBs (PCB 28, PCB 52, PCB 101, PCB 138, PCB 153 and PCB 180) from interfering substances, especially co-eluting PCBs, in particular if levels of samples are in the range of legal limits and non-compliance is to be confirmed. Note: Congeners often found to co-elute are, e.g. PCB 28/31, PCB 52/69 and PCB 138/163/164. For GC/MS also possible interferences from fragments of higher chlorinated congeners have to be considered.For GC/MS techniques: Monitoring of at least: two specific ions for HRMS, two specific ions of m/z > 200 or three specific ions of m/z > 100 for LRMS, 1 precursor and 2 product ions for MS-MS.
Maximum permitted tolerances for abundance ratios for selected mass fragments: Relative deviation of abundance ratio of selected mass fragments from theoretical abundance or calibration standard for target ion (most abundant ion monitored) and qualifier ion(s): Sufficient number of mass fragments with relative intensity > 10 % available, therefore not recommendable to use qualifier ion(s) with a relative intensity of less than 10 % compared to the target ion. Relative intensity of qualifier ion(s) compared to target ion GC-EI-MS (relative deviation) GC-CI-MS, GC-MS n (relative deviation) > 50 % ± 10 % ± 20 % > 20 % to 50 % ± 15 % ± 25 % > 10 % to 20 % ± 20 % ± 30 % ≤ 10 % ± 50 % ± 50 %
For GC/ECD: Confirmation of results exceeding the tolerance with two GC columns with stationary phases of different polarity.
Use of suitable internal standards with physico-chemical properties comparable to analytes of interest. Addition of internal standards: Addition to products (before extraction and clean-up process), Addition also possible to extracted fat (before clean-up process), if maximum level is expressed on fat basis.
Requirements for methods using all six isotope-labelled indicator PCB congeners: Correction of results for recoveries of internal standards, Generally acceptable recoveries of isotope-labelled internal standards are between 50 and 120 %, Lower or higher recoveries for individual congeners with a contribution to the sum of the six indicator PCBs below 10 % are acceptable.
Requirements for methods using not all six isotope-labelled internal standards or other internal standards: Control of recovery of internal standard(s) for every sample, Acceptable recoveries of internal standard(s) between 60 and 120 %, Correction of results for recoveries of internal standards.
The recoveries of unlabelled congeners shall be checked by spiked samples or quality control samples with concentrations in the range of the level of interest. Acceptable recoveries for these congeners are between 70 and 120 %.
| Trueness | – 30 to + 30 % |
|---|---|
| Intermediate precision (RSD %) | ≤ 20 % |
| Difference between upper and lower bound calculation | ≤ 20 % |
In so far as the used analytical procedure makes it possible, the analytical results shall contain the levels of the individual PCB congeners and be reported as lower-bound, upper-bound and medium-bound in order to include a maximum of information in the reporting of the results and thereby enabling the interpretation of the results according to specific requirements. The report shall also include the method used for extraction of PCBs and lipids. The lipid content of the sample shall be determined and reported for food samples with maximum levels expressed on fat basis and an expected fat concentration in the range of 0-2 % (in correspondence to existing legislation), for other samples is the determination of the lipid content optional. The recoveries of the individual internal standards must be made available in case the recoveries are outside the range mentioned in point 6, in case the maximum level is exceeded and in other cases upon request. As the uncertainty of measurement is to be taken into account when deciding about the compliance of a sample, this parameter shall also be made available. Thus, analytical results shall be reported as x +/- U whereby x is the analytical result and U is the expanded measurement uncertainty using a coverage factor of 2 which gives a level of confidence of approximately 95 %. If the uncertainty of measurement is taken into account by applying CCα (as described in Annex II, point IV.1), this parameter shall be reported. The results shall be expressed in the same units and with (at least) the same number of significant figures as the maximum levels laid down in Regulation (EC) No 1881/2006.