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ANNEX I

CHAPTER 1

PERFORMANCE CRITERIA AND OTHER REQUIREMENTS FOR ANALYTICAL METHODS

1.1.    Requirements of screening methods

1.1.1.    Categories of suitable screening methods

Qualitative, semi-quantitative or quantitative methods shall be used as suitable screening methods.

1.1.2.    Requirements for biological, biochemical or physico-chemical screening methods

For prohibited or unauthorised substances, the CCβ shall be as low as reasonably achievable and in any case lower than the reference point of action (RPA) for substances for which RPAs are established under Regulation (EU) 2019/1871.

For authorised pharmacologically active substances, the CCβ shall be lower than the MRL or ML.

Only those analytical methods, for which it can be demonstrated in a documented traceable manner that they are validated and have a false compliant rate lower than or equal to 5 % (β error), shall be used for screening purposes. In the case of a suspected non-compliant result, that result shall be confirmed by a confirmatory method.

Quantitative screening methods, used for both screening and confirmation shall meet the same requirements for accuracy, range, and precision as described in 1.2.2.1 and 1.2.2.2.

1.2.    Requirements of confirmatory methods

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1.2.1.    General requirements for confirmatory methods

For prohibited or unauthorised substances, the CCα shall be as low as reasonably achievable. For prohibited or unauthorised substances, for which an RPA is established under Regulation (EU) 2019/1871 the CCα shall be lower than or equal to the reference point for action.

For authorised substances, the CCα shall be higher than, but as close as possible to, the MRL or ML.

For confirmation purposes, only analytical methods for which it can be demonstrated in a documented traceable manner that they are validated and have a false non-compliant rate (α error) which is less or equal to 1 % for prohibited or unauthorised substances, or which is less or equal to 5 % for authorised substances, shall be used.

Confirmatory methods shall provide information on the structural chemical composition of the analyte. Consequently, confirmatory methods based only on chromatographic analysis without the use of mass spectrometric detection are not suitable on their own for use as confirmatory methods for prohibited or unauthorised pharmacologically active substances. In the case of mass spectrometry not being suitable for authorised substances, other methods such as HPLC-DAD and HPLC-FLD, or a combination of them, can be used.

When required according to the confirmatory method, a suitable internal standard shall be added to the test portion at the beginning of the extraction procedure. Depending on availability, either stable isotope-labelled forms of the analyte, which are particularly suited for mass spectrometric detection, or analogue compounds that are structurally closely related to the analyte, shall be used.

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1.2.1a.    Specific use of Co-chromatography when no internal standard available

When no suitable internal standard can be used, the identification of the analyte shall preferably be confirmed by co-chromatography ( 17 ). In this case, only one peak shall be obtained, the enhanced peak height (or area) being equivalent to the amount of added analyte. If this is not practicable, matrix-matched or matrix-fortified standards shall be used.

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1.2.2.    General performance criteria for confirmatory methods

1.2.2.1.   Trueness by recovery

For repeated analyses of a certified reference material, the deviation of the experimentally determined recovery corrected mean mass fraction from the certified value shall comply with the minimum trueness ranges listed in Table 1.

When no certified reference materials are available, it is acceptable that trueness of measurements is assessed in other ways, such as using materials with assigned values from inter-laboratory studies or through additions of known amounts of the analyte(s) to a blank matrix.

1.2.2.2.   Precision

The coefficient of variation (CV) for the repeated analysis of a reference or fortified material, under within-laboratory reproducibility conditions, shall not exceed the level calculated by the Horwitz Equation. The equation is:

CV = 2(1 – 0,5 log C)

where C is the mass fraction expressed as a power (exponent) of 10 (e.g. 1 mg/g = 10-3). For mass fractions below 120 μg/kg the application of the Horwitz equation yields unacceptably high values. Therefore, the allowed maximum coefficient of variation shall not be greater than the values presented in Table 2.

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For analyses carried out under repeatability conditions, the coefficient of variation under repeatability conditions is usually below two thirds of the values listed in Table 2 and shall be lower than or equal to the coefficient of variation under reproducibility conditions.

1.2.3.    Requirements for chromatographic separation

1.2.3.1.   Minimum acceptable retention time

For liquid (LC) or gas chromatography (GC), the minimum acceptable retention time for the analyte(s) under examination shall be twice the retention time corresponding to the void volume of the column.

1.2.3.2.   Retention time of the analyte in the extract

The retention time of the analyte in the extract shall correspond to that of the calibration standard, a matrix-matched standard or a matrix-fortified standard with a tolerance of ± 0,1 minute. For fast chromatography, where the retention time is below 2 minutes, a deviation of less than 5 % of the retention time is acceptable.

1.2.3.3.   Retention time in case of using of internal standard

In case an internal standard is used, the ratio of the chromatographic retention time of the analyte to that of the internal standard, that means the relative retention time of the analyte, shall correspond to that of the calibration standard, matrix-matched standard or matrix-fortified standard with a maximum deviation 0,5 % for gas chromatography and 1 % for liquid chromatography for methods validated from the date of entry into force of this Regulation.

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1.2.4.    Specific performance criteria for mass spectrometry

1.2.4.1.   Mass spectrometric detection

Mass spectrometric detection shall be carried out by using some of the following options:

Both low-resolution mass spectrometry (LRMS, at unit mass resolution) and high-resolution mass spectrometry (HRMS), including e.g. double focusing sectors, Time of Flight (TOF) and Orbitrap instruments are appropriate.

For confirmation of the identity of an analyte in high-resolution mass spectrometry (HRMS) the mass deviation of all diagnostic ions shall be below 5 ppm (or in case of m/z < 200 below 1 mDa). On basis of this the effective resolution should be selected fit for purpose and the resolution shall typically be greater than 10 000 for the entire mass range at 10 % valley or 20 000 at full width at half maximum (FWHM).

When mass spectrometric determination is performed by the recording of full scan spectra (both LRMS and HRMS), only diagnostic ions with a relative intensity of more than 10 % in the reference spectrum of the calibration standard, matrix-matched standard or matrix-fortified standards are suitable. Diagnostic ions shall include the molecular ion (if present at ≥ 10 % intensity of the base peak) and characteristic fragment or product ions.

Precursor ion selection: When mass spectrometric determination is performed by fragmentation after precursor ion selection, precursor ion selection is carried out at unit mass resolution or better. The selected precursor ion shall be the molecular ion, characteristic adducts of the molecular ion, characteristic product ions or one of their isotope ions. In case the precursor selection has a mass selection window of more than one Dalton (e.g. in case of Data Independent Acquisition) the technique is considered as full-scan confirmatory analysis.

Fragment and product ions: The selected fragment or product ions shall be diagnostic fragment for the analyte/product measured. Non-selective transitions (e.g. the tropylium cation or loss of water) shall be omitted whenever possible. The abundance of diagnostic ions shall be determined from the peak area or height of integrated extracted ion chromatograms. This is also applicable when full-scan measurements are used for identification. The signal-to-noise (S/N) ratio of all diagnostic ions shall be greater or equal than three to one (3:1).

Relative intensities: The relative intensities of the diagnostic ions (ion ratio) are expressed as a percentage of the intensity of the most abundant ion or transition. The ion ratio has to be determined by comparing spectra or by integrating the signals of the extracted ion mass traces. The ion ratio of the analyte to be confirmed shall correspond to those of the matrix-matched standards, matrix-fortified standards or standard solutions at comparable concentrations, measured under the same conditions, within ± 40 % relative deviation.

For all mass spectrometric analyses, at least one ion ratio shall be determined. These are preferably ions obtained within a single scan, but the ions can also originate from different scans in the same injection (i.e. full scan and fragmentation scan).

1.2.4.2.   Identification

A system of identification points shall be used to select adequate acquisition modes and evaluation criteria. For confirmation of the identity of substances in a matrix for which an MRL is established (authorised use), a minimum of 4 identification points is required. For unauthorised or prohibited substances, 5 identification points are required. One point can originate from the chromatographic separation. Table 3 shows the number of identification points that each of the techniques yields. To qualify for the identification points required for confirmation, identification points obtained from different techniques can be added.

1.2.5.    Specific performance criteria for the determination of an analyte using liquid chromatography with detection techniques other than mass spectrometry

For authorised substances only, the following techniques can be used as alternative for mass spectrometry based methods, provided that the relevant criteria for these techniques are fulfilled:

Liquid chromatography with UV/VIS detection (single wavelength) is not suitable on its own for use as a confirmatory method.

1.2.5.1.   Performance criteria for full-scan diode array spectrophotometry

The performance criteria for chromatographic separation included in Chapter 1.2.3 shall be fulfilled.

The absorption maxima in the UV spectrum of the analyte shall be at the same wavelengths as those of the calibration standard in matrix within a maximum margin, which is determined by the resolution of the detection system. For diode array detection, this maximum margin is typically within ± 2 nm. The spectrum of the analyte above 220 nm shall, for those parts of the two spectra with a relative absorbance greater than or equal to 10 %, not be visibly different from the spectrum of the calibration standard. This criterion is met when firstly the same maxima are present and secondly when the difference between the two spectra is at no point greater than 10 % of the absorbance of the calibration standard. In the case computer-aided library, searching and matching are used, the comparison of the spectral data in the official samples to that of the calibration solution has to exceed a critical match factor. This factor shall be determined during the validation process for every analyte on the basis of spectra for which the criteria described above are fulfilled. Variability in the spectra caused by the sample matrix and the detector performance shall be checked.

1.2.5.2.   Performance criteria for fluorescence detection spectrophotometry

The performance criteria for chromatographic separation included in Chapter 1.2.3 shall be fulfilled.

The selection of the excitation and emission wavelengths in combination with the chromatographic conditions shall be done in such a way to minimise the effects of interfering components in blank sample extracts. There should be a minimum of 50 nanometres between the excitation and emission wavelength.

The nearest peak maximum in the chromatogram shall be separated from the designated analyte peak by at least one full peak width at 10 % of the maximum height of the analyte peak.

This applies to molecules that exhibit native fluorescence and to molecules that exhibit fluorescence after either transformation or derivatisation.

CHAPTER 2

VALIDATION

2.1.    Performance characteristics to be determined for analytical methods

By means of the validation of the method, it shall be demonstrated that the analytical method complies with the criteria applicable for the relevant performance characteristics. Different control purposes require different categories of methods. Table 5 determines which performance characteristic shall be verified for which type of method, further explanation of each parameter is given in this chapter.

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2.2.    Trueness, repeatability and within-laboratory reproducibility

This chapter provides examples and references for validation procedures. Other approaches to demonstrate that the method complies with performance criteria may be used, provided that they achieve the same level and quality of information.

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2.2.1.    Conventional validation

The calculation of the parameters in accordance with conventional methods requires the performance of several individual experiments (see Table 5 in this Annex). For major changes the ongoing validity of the performance characteristics has to be verified. For multi-analyte methods, several analytes can be analysed simultaneously, as long as possibly relevant interferences have been ruled out. Several performance characteristics can be determined in a similar way. Therefore, in order to minimise the workload, it is advised to combine experiments as much as possible (e.g., repeatability and within-laboratory reproducibility with specificity, analysis of blank samples to determine the decision limit for confirmation and testing for specificity).

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2.2.1.1.   Trueness on the basis of a certified reference material

It is preferred to determine the trueness of an analytical method by means of certified reference material (CRM). The procedure for this is described in ISO 5725-4:1994 ( 18 ).

An example is given below:

Trueness (%) = (mean recovery-corrected concentration detected) × 100/certified value

2.2.1.2.   Trueness on basis of fortified samples

If no certified reference material is available, the trueness of the method shall be determined by experiments using a fortified blank matrix, as a minimum in accordance with the following scheme:

Trueness (%) = (mean recovery-corrected concentration detected) × 100/fortification level

For methods for authorised substances validated before the date of application of this Regulation, a determination of the trueness of the method using 6 fortified aliquots at 0,5, 1,0 and 1,5 times the MRL or ML is sufficient.

2.2.1.3.   Repeatability

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For methods for authorised substances validated before the date of entry into force of this Regulation, a determination of the repeatability with fortified matrices in concentrations at 0,5, 1,0 and 1,5 times the MRL or ML is sufficient.

Alternatively, the calculation for repeatability can be performed according to ISO 5725-2:2019 ( 22 ).

2.2.1.4.   Within-laboratory reproducibility

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For methods for authorised substances validated before the date of entry into force of this Regulation, a determination of the within-laboratory reproducibility with fortified matrices in concentrations at 0,5, 1,0 and 1,5 times the MRL or ML is sufficient.

Alternatively, the calculation for within-laboratory reproducibility/intermediate precision can also be performed according to ISO 5725-2:2019, ISO 11843-1:1997 ( 24 ), Codex CAC/GL 59-2006 ( 25 ).

2.2.2.    Validation according to alternative models

The calculation of the parameters in accordance with alternative models requires the performance of an experimental plan. The experimental plan shall be designed depending on the number of different species and different factors under investigation. Hence, the first step of the entire validation procedure is to consider the sample populations that will be analysed in the laboratory in the future, in order to determine the most important species and the factors, which may influence the measurement results. The factorial approach allows the assessment of the measurement uncertainty of the test results, obtained under a variety of test conditions in a given laboratory, such as different analysts, different instruments, different lots of reagents, different matrices, different elapsed assay times and different assay temperatures. Subsequently, the concentration range has to be chosen in a purpose-adapted way according to the MRL or ML for authorised substances or the RPA or LCL for prohibited or unauthorised substances.

The factorial approach aims at establishing reliable precision data and measurement data by simultaneous controlled variation of the selected factors. It allows the evaluation of the combined impact of factorial effects and random effects. The experimental design allows also the investigation of the ruggedness ( 26 ) of the analytical method and the determination of the in-house reproducibility standard deviation across matrices.

In the following an example for an alternative approach using an orthogonal experimental design plan is given.

Up to seven factors (noise factors) can be examined. The study is designed in such a way that precision, trueness (based on fortified samples), sensitivity, measurement uncertainty and critical concentrations can be determined simultaneously by implementation of the experimental plan.

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The calculation of the method characteristics shall be performed as described by Jülicher et al. ( 27 ) or by ISO/TS 23471:2022 ( 28 ).

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2.2.3.    Other validation approaches

Other approaches to demonstrate that the method complies with performance criteria for the performance characteristics may be used, provided that they achieve the same level and quality of information. Validation can also be performed by conducting an inter-laboratory study such as established by Codex Alimentarius, ISO or the IUPAC ( 29 ), or according to alternative methods such as single laboratory studies or in-house validation ( 30 ). When alternative validation procedures are applied, the underlying model and strategy with the respective prerequisites, assumptions and formulae shall be laid down in the validation protocol or at least references shall be given to their availability.

2.3.    Selectivity/Specificity

The power of discrimination between the analyte and closely related substances shall be determined to the best possible extent. Interference of homologues, isomers, degradation products, endogenous substances, analogues, metabolic products of the residue of interest, of matrix compounds or of any other possibly interfering substance shall be determined and if needed the method shall be amended to avoid the identified interferences. For determining the specificity of the method, the following approach shall be used:

2.4.    Ruggedness

The analytical method shall be tested for its continued performance under different experimental conditions, which include for example different sampling conditions and minor changes that can occur in routine testing. For testing the ruggedness of the method, the changes introduced in the experimental conditions should be minor. The importance of these changes shall be evaluated. Each performance characteristic shall be determined for all minor changes that have been shown to have a significant effect on the performance of the assay.

2.5.    Stability

The stability of the calibration standard, matrix-matched standard and/or matrix-fortified standards and of analyte or matrix constituents in the sample during storage or analysis shall be determined, as instabilities might influence the test results.

Usually the analyte stability is well characterised under various storage conditions. The experiments carried out for monitoring the storage conditions of standards and samples, which are carried out as part of the normal laboratory accreditation and quality control system, can provide the required information. If stability data for analytes in the matrix are available (e.g. on the basis of information from the EURLs, published data, etc.), these data do not need to be determined by each laboratory. However, referring to available stability data of analytes in solution and in matrix is only acceptable if identical conditions are applied.

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In case the required stability data are not available, the following approaches should be used. In addition, also the application of an isochronous approach ( 31 ) with a storage temperature scheme similar to the one in Table 7 of this Annex allows a determination of potential analyte instabilities and also an estimation of appropriate storage periods, and may also be used.

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2.5.1.    Determination of the stability of the analyte in solution

Analyte Remaining (%) = Ci × 100/Cfresh

Ci = concentration at time point i

Cfresh = concentration of fresh solution

The mean value of five replicate solutions, which were stored, shall not differ by more than 15 % from the mean value of five freshly prepared replicate solutions. The mean value of the five freshly prepared solutions shall be used as the basis for calculating the percentage difference.

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2.5.2.    Determination of the stability of analyte(s) in matrix

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2.6.    Decision limit for confirmation (CCα)

The CCα shall be determined for confirmatory methods. The CCα shall be established under conditions complying with the requirements for identification or identification plus quantification as defined under ‘Performance criteria and other requirements for analytical methods’ as laid down in Chapter 1.

For the control of the compliance of samples, the combined standard measurement uncertainty has already been taken into account in the CCα value (decision limit for confirmation).

2.7.    Detection capability for screening (CCβ)

The CCβ shall be determined for screening methods. The CCβ shall be established as defined under ‘Performance criteria and other requirements for analytical methods’ as laid down in Chapter 1 of this Annex and according to the requirements laid down in Table 5. However, the full requirements for identification (cf. 1.2.3, 1.2.4, 1.2.5) do not need to be applied for screening methods.

2.8.    Calibration curves

When calibration curves are used for quantification:

For calibration curves based on a standard solution, matrix-matched standards or matrix-fortified standards acceptable ranges shall be indicated for the parameters of the calibration curve, which may vary from series to series.

2.9.    Absolute recovery

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The absolute recovery of the method does not need to be determined if an internal standard, a matrix-fortified calibration or both mentioned are available. In all other cases, the absolute recovery of the method shall be determined.

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When requirements for trueness, as set out in Table 1, are fulfilled, a fixed correction factor may be used. Otherwise, the recovery factor obtained for that specific batch shall be used. Alternatively, the standard addition ( 34 ) procedure or an internal standard shall be used instead of using a recovery correction factor.

The absolute recovery shall be calculated for at least six representative lots of matrix.

An aliquot of blank matrix shall be fortified with the analyte before extraction, and a second aliquot of blank matrix shall be fortified after sample preparation at a relevant concentration level and the concentration of the analyte shall be determined.

The recovery shall be calculated as:

Rec (analyte) = (area matrix-fortified standard)/(area matrix-matched standard) × 100

2.10.    Relative matrix effects

The relative matrix effect shall be determined in all cases. This can be done either as part of the validation or in separate experiments. The calculation of the relative matrix effect shall be done for at least 20 different blanks lots (matrix/species), according to the scope of the method e.g. different species to be covered.

The blank matrix should be fortified after extraction with the analyte at the RPA, MRL or ML and should be analysed together with a pure solution of the analyte.

The relative matrix effect or matrix factor (MF) is calculated as:

IS : internal standard

MMS : matrix-matched standard

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The coefficient of variation shall not be greater than the values listed in Table 2 of this Annex for the MF (standard normalised for IS).

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CHAPTER 3

QUALITY CONTROL DURING ROUTINE ANALYSIS – ONGOING METHOD PERFORMANCE VERIFICATION

The requirements for assuring the quality of analytical results of Chapter 7.7 of ISO/IEC 17025:2017 ( 35 ) shall be complied with.

During routine analysis, the analysis of certified reference materials (CRMs) is the preferable option to provide evidence of method performance. Since CRMs that contain the relevant analytes at the required concentration levels are seldom available, also reference materials provided and characterised by the EURLs or laboratories that hold an ISO/IEC 17043:2010 ( 36 ) accreditation may be used as an alternative. As another alternative in-house reference materials, which are controlled regularly, may be used.

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During routine analysis, the analysis of certified reference materials (CRMs) is the preferable option to provide evidence of method performance. Since CRMs that contain the relevant analytes at the required concentration levels are seldom available, also reference materials provided and characterised by the EURLs or laboratories that hold an ISO/IEC 17043:2023 ( 37 ) accreditation may be used as an alternative. As another alternative in-house reference materials, which are controlled regularly, may be used.

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The following order is recommended for the quality control samples: control sample for system suitability of the instrument, compliant control sample, sample(s) to be confirmed, compliant control sample again and fortified quality control sample (non-compliant control samples).

For quantitative methods with each batch of official samples, a calibration curve shall be analysed and measured before or after the above listed samples.

Where practicable, trueness (on basis of fortified samples) of all target analytes in the non-compliant control samples shall be evaluated, by means of quality control charts in accordance with Chapter 7.7 of ISO/IEC 17025:2017. If this requires a disproportionately large number of trueness determinations, the number of analytes may be reduced to a number of representative analytes.

CHAPTER 4

EXTENSION OF THE VALIDATED SCOPE OF A PREVIOUSLY VALIDATED METHOD

Sometimes it is necessary to extend the scope of a previously comprehensively validated method. In these cases an extension of the scope should be accomplished in an efficient and analytically sound way. This can be achieved by carrying out a validation on a reduced number of samples (e.g. the half number of samples) compared to a full validation.

Nevertheless, the type and number of modifications to be validated in a single reduced validation scheme shall always be based on expert knowledge and previous experiences, e.g. a change in detection technique would require a complete validation in any case.

In general, to assure the ongoing validity of the method, its performance shall be monitored continuously and compared to the initially obtained validation parameters. Ideally, this ongoing method performance control is designed in a way that the missing data for a complete validation can be collected over time (e.g. with a few data points from QC samples in each analytical series).

4.1.    Extensions of methods as regards to the range of concentrations

Due to changes of MRLs, MLs, and RPAs it may become necessary to adjust the concentration range for which a method is validated. For such a case, the application of a reduced validation scheme is acceptable.

Calibration curves for the modified range should be prepared according to the validated procedure. Different batches fortified at different concentration levels (cf. 2.2.1, 2.2.2) should be analysed. Trueness, repeatability and within-laboratory reproducibility/intermediate precision should be within an acceptable range compared to those of the originally validated method. A recalculation of CCβ (screening methods) and CCα (confirmation methods) should be performed, where relevant.

4.2.    Extensions of methods as regards to additional substances

Generally, the method extension to additional compounds is only possible for analytes, which are similar structure and characteristic-wise compared to those already included in the analytical method. For such a case, the application of a reduced validation scheme is acceptable. Likewise, no divergence from the method description is allowed.

Calibration curves for the additional substances should be prepared according to the validated procedure. Different batches of matrix materials fortified at different concentration levels (cf. 2.2.1, 2.2.2) should be analysed. Trueness, repeatability and within-laboratory reproducibility/intermediate precision should be within a comparable range to those of the other analytes of the originally validated method and in line with the requirements set in 1.2.2. A calculation of CCβ (screening methods) and CCα (confirmation methods) for the new analytes has to be done.

4.3.    Extensions of methods as regards to matrices/species

The inclusion of new matrices or species in an already validated analytical method shall always be a case-by-case decision based on the knowledge and experiences gained so far with the method and preliminary experiments assessing potential matrix effects and interferences. Generally, this will only be possible for matrices that exhibit similar properties and for non-critical analytes (stability, detectability).

Calibration curves (standard or matrix) should be prepared according to the validated procedure. Different batches of matrix material fortified at different concentration levels (cf. 2.2.1, 2.2.2) should be analysed. Trueness, repeatability and within-laboratory reproducibility/intermediate precision should be within an acceptable range to those of the originally validated method and in line with the requirements set in 1.2.2. Depending on the validation approach, a recalculation of CCβ (screening methods) or CCα (confirmation methods) might be necessary.

If the results are not within an acceptable range compared to the values for the original matrix, an additional full validation will be necessary, in order to determine the matrix/species specific performance parameters.

In cases where MRLs for a specific substance differ for certain matrices, it will most likely be difficult to adapt the method scope to the additional matrix/species and concentration, since in this case two modifications have to be considered. In such cases a full validation is recommended.

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ANNEX II

SAMPLING PROCEDURES AND OFFICIAL SAMPLE TREATMENT

1.    Sample quantity

The minimum sample quantities shall be defined in the national residue control programme. The minimum sample quantities shall be sufficient to enable the approved laboratories to carry out the analytical procedures necessary to complete the screening and the confirmatory analyses. Specifically for poultry, aquaculture, rabbits, farmed game, reptiles and insects a sample consists out of one or more animals, depending the requirements of the analytical methods. For eggs, the sample size is at least 12 eggs or more, according to the analytical methods used. In case several substance categories need to be analysed in one sample with different analytical methods, the sample size shall be increased accordingly.

2.    Division into sub-samples

Unless technically impossible or not required by national legislation, each sample shall be divided into at least two equivalent sub-samples each allowing the complete analytical procedure. The subdivision can take place at the sampling location or in the laboratory.

3.    Traceability

Each sample shall be taken in such way that it is always possible to trace it back to the farm of origin and the batch of animals or the individual animal, where relevant. In particular, for milk, according to the choice of the Member State, the samples can be taken, in either of the following places:

4.    Sample containers

Samples shall be collected in suitable containers to maintain sample integrity and traceability. In particular, containers shall prevent substitution, cross-contamination and degradation. The containers shall be officially sealed.

5.    Sampling report

A report shall be produced after each sampling procedure.

The inspector collects at least the following data in the sampling report:

Paper or electronic copies of the report are to be provided depending on the sampling procedure. The sampling report and its copies shall be completed in a way that ensures their authenticity and legal validity, which may require that these documents are signed by the inspector. In case of on-farm sampling, the farmer or his deputy may be invited to sign the original sampling report.

The original of the sampling report remains at the competent authority, which has to guarantee that unauthorised persons cannot access this original report.

If necessary, the farmer or the owner of the establishment may be informed of the sampling undertaken.

6.    Sampling report for the laboratory

The sampling report for the laboratory established by the competent authorities shall be in accordance with the requirements set in Chapter 7 of ISO/IEC 17025:2017 ( 38 ) and shall contain at least the following information:

The sampling report for the laboratory shall accompany the sample when sent to the laboratory.

7.    Transport and storage

Residue control programmes shall specify the suitable storage and transport conditions for each analyte/matrix combination to ensure analyte stability and sample integrity. The transport time shall be as short as possible and the temperature during transport shall be adequate to ensure analyte stability.

Specific attention shall be paid to transport boxes, temperature and delivery times to the responsible laboratory.

In case of any non-compliance with the requirements of the control programme, the laboratory shall inform the competent authority without delay.