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GB 31604.59-2023: National food safety standard - Food contact materials and products - General rules for verification of chemical analysis methods
GB 31604.59-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Food Contact Materials
and Products - General Rules for Verification of Chemical
Analysis Methods
ISSUED ON. SEPTEMBER 6, 2023
IMPLEMENTED ON. SEPTEMBER 6, 2024
Issued by. National Health Commission of the People’s Republic of China;
State Administration for Market Regulation.
Table of Contents
1 Scope... 3
2 Terms and Definitions... 3
3 General Requirements for the Verification of Chemical Analysis Methods for Food
Contact Materials and Products... 3
4 Verification of Analysis Method for Residue... 4
4.1 Selection of Representative Materials (or products) and Requirements for Verification
Samples... 4
4.2 Verification of Performance Parameters of Analysis Method for Residue... 6
4.3 Method Equivalence Verification... 12
4.4 Requirements for Data Processing... 13
5 Verification of Analysis Method for Specific Migration Amount... 13
5.1 Selection of Representative Materials (or products), and Food Simulants, and
Requirements for Soaking Solutions for Verification... 13
5.2 Verification of Performance Parameters of Analysis Method for Target Analyte Content
in Soaking Solution... 14
5.3 Conversion of Target Analyte Content in the Soaking Solution and Specific Migration
Amount... 19
5.4 Method Equivalence Verification... 20
5.5 Requirements for Data Processing... 20
Appendix A Classification of Materials Used for the Verification of Chemical Analysis
Methods for Food Contact Materials and Products... 21
National Food Safety Standard - Food Contact Materials
and Products - General Rules for Verification of Chemical
Analysis Methods
1 Scope
This Standard specifies general requirements for the verification of chemical analysis methods
for food contact materials and products.
This Standard is applicable to the verification of the formulation and revision process of
chemical analysis methods for food contact materials and products in national food safety
standards.
2 Terms and Definitions
What is defined in GB 5009.295-2023 and the following terms and definitions are applicable
to this document.
2.1 Chemical Alternative Solvents
Chemical solvents used to replace oil-containing food simulants (vegetable oil) in chemical
solvent substitution test, such as. 95% (volume fraction) ethanol solution, isooctane, n-hexane
and n-heptane, etc.
2.2 Soaking Solution
The solution obtained after food contact materials and products undergo a migration test with
food simulants or chemical alternative solvents.
3 General Requirements for the Verification of Chemical
Analysis Methods for Food Contact Materials and Products
3.1 For qualitative method, intra-laboratory and inter-laboratory verification parameters shall
include the specificity and detection limit of the method.
3.2 For quantitative method, intra-laboratory verification parameters shall include the
specificity, detection limit, quantification limit, determination range, accuracy and repeatability
of the method; inter-laboratory verification parameters shall include the detection limit,
quantification limit, determination range, accuracy and reproducibility of the method.
each type of food contact materials, select at least one subtype of food contact materials. For
each subtype, select at least one representative material (or product).
4.1.1.4 When selecting composite materials and products for food contact for the method
verification, the number of types of food contact materials covered shall be calculated based on
the types corresponding to the materials of each layer within the effective barrier layer.
4.1.2 Requirements for verification samples
4.1.2.1 Verification samples can be selected from certified reference materials / standard
samples, quality control samples that comply with the proficiency verification requirements, or
standard addition samples.
4.1.2.2 When selecting certified reference materials / standard samples for verification, there
shall be at least 3 concentration levels, including the lowest concentration, intermediate
concentration (generally, the concentration of concern) and the highest concentration of the
determination range of the method.
4.1.2.3 When selecting quality control samples that comply with the proficiency verification
requirements, the verification samples must satisfy the following conditions.
a) The selection of sample matrix shall be representative and satisfy the expected use of
the method;
b) For a sample matrix, at least 3 concentration addition levels are required, including
the lowest concentration, intermediate concentration (generally, the concentration of
concern) and the highest concentration of the determination range of the method. In
addition, their uniformity and stability shall be tested.
4.1.2.4 When selecting standard addition samples for verification, the verification samples can
be prepared in accordance with the following method.
a) The selection of sample matrix shall be representative and satisfy the expected use of
the method;
b) For the selected representative material (or product), after homogenizing it in
accordance with the method, add the target analyte to it. At least 3 concentrations are
required to be added, including the lowest concentration, intermediate concentration
(generally, the concentration of concern) and the highest concentration of the
determination range of the method.
4.1.3 Sample storage and transportation
4.1.3.1 When it is necessary to send and transport the verification samples, each sample shall
be individually sealed and packaged, and the packaging used shall not contain substances that
may affect the detection of the target analyte. Severe friction or collision of samples during
transportation shall be avoided.
4.1.3.2 If the target analyte is a volatile substance, effective measures shall be taken to avoid
losses caused by the volatilization of the target analyte during the transportation of the samples,
such as. multiple sealing of the samples and maintaining at a low temperature, etc.
4.2 Verification of Performance Parameters of Analysis Method for Residue
4.2.1 Specificity
4.2.1.1 Verification requirements
The analysis method’s capability of distinguishing the target analyte from other substances
(including but not limited to impurity components, such as. isomers and homologues that may
be included in the industrial grade target analyte, and oxidation / reduction / decomposition /
hydrolysis / pyrolysis that may occur during industrial production of the target analyte, as well
as matrix components, etc.) shall be verified. There shall be no interference factors (signals and
interference peaks, etc.) that may lead to errors in the qualitative determination of the target
analyte and affect the accuracy of the quantitative determination.
4.2.1.2 Verification method
Analyze representative samples that match the scope of application of the method, and check
whether there are interferences (signals and peaks, etc.) that may lead to errors in the qualitative
determination of the target analyte and / or affect the accuracy of the quantitative determination;
add a certain concentration of substances that may interfere with the qualitative and / or
quantitative determination of the target analyte to the representative materials (or products),
then, perform analysis to check whether these interfering substances can be effectively
identified.
4.2.2 Detection limit
4.2.2.1 Verification requirements
The detection probability of the target analyte at the detection limit level shall be not lower than
95% (at the 95% confidence level); the detection limit of each representative material (or
product) needs to be independently verified.
4.2.2.2 Verification method
4.2.2.2.1 Estimation methods
The estimation methods for the detection limit include.
a) Signal-to-noise ratio method (applicable to spectroscopy, chromatography and mass
spectrometry). add the target analyte to the blank sample matrix, and take the addition
concentration when the signal-to-noise ratio is 3 as the estimated detection limit;
b) Blank standard deviation method (applicable to non-zero response values of blank
samples). by analyzing a large number of sample blanks, determine the detection limit.
The number of independent tests shall be no less than 10 times (n  10). Calculate the
standard deviation of the sample blank response values. The concentration
corresponding to the average value of the sample blank response values plus 3 times
the standard deviation is the estimated detection limit;
c) Calibration equation estimation method (applicable to instrumental method). if
sample data at or near the detection limit cannot be obtained, take 3S/b (S is the
standard deviation of the calibration curve, and b is the slope of the calibration curve)
as the estimated detection limit;
d) Stepwise dilution method (applicable to all methods). at certain concentration
intervals, conduct stepwise dilution on the target analyte; in accordance with the
method to be verified, perform the detection. The concentration, at which the target
analyte can be detected, is the estimated detection limit.
4.2.2.2.2 Determination method
Select representative materials (or products) of the matrix blank, each containing at least 20
parallel samples. Respectively add target analytes with estimated detection limit concentrations.
When the detection probability of the target analyte is not lower than 95%, it is determined as
the detection limit; when it is impossible to obtain the matrix blank sample of a certain
representative material (or product), a matrix blank sample of the same material type and for
non-food contact use can be used for verification; when the matrix blank sample of all
representative materials (or products) cannot be obtained, isotope-labeled compounds or
structural analogs of the target analyte can be used for verification.
4.2.3 Quantification limit
4.2.3.1 Verification requirements
The quantification limit shall be verified using certified reference materials / standard samples,
quality control samples or standard addition samples of the same concentration. Its accuracy
and precision shall satisfy the method and regulatory requirements. The quantification limit
plus 3 times the standard deviation of the sample at the concentration of concern shall be less
than the concentration of concern. For target analytes with limited values, the quantification
limit shall be 0.5 times the limit values or less.
4.2.3.2 Verification method
4.2.3.2.1 Estimation methods
The estimation methods for the quantification limit include.
a) Add the target analyte to the blank sample matrix, and take the addition concentration
with the signal-to-noise ratio of 10 as the estimated quantification limit;
b) Use 3 times the detection limit as the estimated quantification limit;
4.2.7.3 Evaluation of stability verification results
4.2.7.3.1 The stability of target analytes with only two time point detection results can be
evaluated using Formula (1).
Where,
ρi---the determined concentration of the target analyte at the time point i;
ρ0---the initial determined concentration of the target analyte;
UE---the expanded uncertainty of the instrumental method (excluding sample pre-treatment
steps) at the concentration ρ0, UE  15%.
4.2.7.3.2 The stability of target analytes with multiple time point detection results can be
evaluated using t test method or F test method.
4.2.8 Robustness
The robustness test is a testing procedure that examines the impact of environmental or other
conditional variables on an analysis method. A robust analysis method shall not significantly
change due to small changes in factors like the environment. In other words, it shall be
insensitive to changes in environmental factors, such as. temperature, humidity and air pressure,
etc., as well as to other factors, such as. the amount of reagent added and reaction time, etc. The
robustness test of a method is shown in Appendix B of GB 5009.295-2023 National Food Safety
Standard - General Rules for Verification of Chemical Analysis Methods.
4.3 Method Equivalence Verification
4.3.1 Verification requirements
In the standards of analysis methods, there shall be no significant difference in the test results
of different analysis methods with the same determination range.
4.3.2 Verification method
4.3.2.1 When verifying the equivalence of residue analysis method, at least three representative
material (or product) samples shall be selected. For each type of representative material (or
product), the method to be verified must use at least 6 reference materials / standard samples or
standard addition samples to detect the target analyte at the concentration of concern.
4.3.2.2 The t test method, F test method, Bland-Altman statistical chart method, measurement
uncertainty method or two-way one-sided t test method can be used to test the consistency of
the test data between two or more methods.
4.4 Requirements for Data Processing
All laboratory verification data needs to be subject to outlier testing and statistical analysis. The
analysis method can adopt statistical methods, for example, Grubbs test. After eliminating
outliers through technical analysis, the number of laboratories and the amount of verification
data shall comply with the statistical requirements.
5 Verification of Analysis Method for Specific Migration
Amount
5.1 Selection of Representative Materials (or products), and Food Simulants, and
Requirements for Soaking Solutions for Verification
5.1.1 Selection of representative materials (or products)
Same as 4.1.1.
5.1.2 Selection of food simulants
5.1.2.1 During intra-laboratory verification, for each representative material (or product) that
needs to be verified, all food simulants and chemical alternative solvents, to which, the method
is applicable, shall be covered.
5.1.2.2 During inter-laboratory verification, for each representative material (or product)...