This standard specifies the terms and definitions, principles, instruments and equipment, determination, result processing and presentation, confirmation and treatment of abnormal samples, accuracy and precision, and test report requirements for the determination of crude protein content (dry basis) of corn by near infrared analysis. This standard applies to the rapid determination of crude protein content (dry basis) in corn. This standard does not apply to arbitration inspection. GB/T 24901-2010 Grain and oil inspection Determination of crude protein content of corn by near infrared method GB/T24901-2010 Standard download decompression password: www.bzxz.net
This standard specifies the terms and definitions, principles, instruments and equipment, determination, result processing and presentation, confirmation and treatment of abnormal samples, accuracy and precision, and test report requirements for the determination of crude protein content (dry basis) of corn by near infrared analysis. This standard applies to the rapid determination of crude protein content (dry basis) in corn. This standard does not apply to arbitration inspection.
This standard is a rapid determination method for crude protein content (dry basis) in corn based on the classical method. For arbitration inspection, the conventional method specified in the national standard, namely GB/T5511 "Determination of nitrogen content of cereals and legumes and calculation of crude protein content by Kjeldahl method" shall prevail.
Appendix A of this standard is a normative appendix.
This standard is proposed by the State Administration of Grain.
This standard is under the jurisdiction of the National Technical Committee for Grain and Oil Standardization.
Drafting units of this standard: Standard Quality Center of the State Administration of Grain, Henan University of Technology, Hubei Grain and Oil Quality Monitoring Station, Liaoning Grain and Oil Quality Inspection Institute, Beijing Grain, Oil and Food Inspection Institute.
Main drafters of this standard: Tang Ruiming, Chen Jie, Wu Cunrong, Ni Shanshan, Qiao Lina, Min Guochun, Wang Lidan.
The clauses in the following documents become the clauses of this standard through reference in this standard. For dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to agreements based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest versions apply to this standard.
GB5491 Sampling and subsampling methods for grain and oilseed inspection
GB/T5511 Determination of nitrogen content and calculation of crude protein content in cereals and legumes by Kjeldahl method
GB/T24895 General rules for verification of calibration model and network management and maintenance of near infrared analysis for grain and oil inspection

ICS.67.060
National Standard of the People's Republic of China
GB/T24901—2010
Inspection of grain and oils
Determination of crude protein in maize
Near-infrared method
Inspection of grain and oils-Determination of crude protein in maize-Near-infrared method
Issued on 2010-06-30
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Administration of Standardization of the People's Republic of China
Implementation on 2011-01-01
GB/T24901—2010
This standard is a rapid determination method for crude protein content (dry basis) in maize based on the classical method. For arbitration inspection, the conventional method specified in the national standard, i.e. GB/T5511 "Cereals and Legumes" shall prevail.
Appendix A of this standard is a normative appendix.
This standard is proposed by the State Administration of Grain.
This standard is under the jurisdiction of the National Technical Committee for Grain and Oil Standardization. Determination of nitrogen content and calculation of crude protein content by Kjeldahl method
The drafting units of this standard are: Standard and Quality Center of the State Administration of Grain, Henan University of Technology, Hubei Grain and Oil Quality Monitoring Station, Liaoning Grain and Oil Quality Inspection Institute, Beijing Grain, Oil and Food Inspection Institute. The main drafters of this standard are: Tang Ruiming, Chen Jie, Wu Cunrong, Ni Shanna, Qiao Lina, Min Guochun, Wang Lidan. I
1 Scope
Grain and Oil Inspection
Determination of Crude Protein Content of Corn
Near Infrared Method
GB/T24901—2010
This standard specifies the terms and definitions, principles, instruments and equipment, determination, result processing and expression, confirmation and processing of abnormal samples, accuracy and precision, and test report requirements for the determination of crude protein content (dry basis) of corn by near infrared analysis method. This standard applies to the rapid determination of crude protein content (dry basis) in corn. This standard does not apply to arbitration inspection.
2 Normative references
The clauses in the following documents become clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version applies to this standard. GB5491 Sampling and splitting method for inspection of grains and oilseeds GB/T5511 Determination of nitrogen content and calculation of crude protein content of cereals and beans Kjeldahl method for inspection of grains and oils General rules for calibration model verification and network management and maintenance of near infrared analysis GB/T24895
3 Terms and definitions
The terms and definitions established in GB/T24895 apply to this standard. 4 Principle
Using the absorption characteristics of near-infrared light by the overtone vibration or rotation of chemical bonds such as C-H, N-H, and O-H in protein molecules, the correlation between the near-infrared spectrum of corn samples and their crude protein is established by chemometric methods to calculate the crude protein content of corn samples.
5 Instruments and Equipment
5.1 Near-infrared Analyzer: Instruments that join the near-infrared analysis network of grains and oils should meet the requirements of GB/T24895. Instruments that do not join the near-infrared analysis network of grains and oils should be verified in accordance with the provisions of GB/T24895 on calibration model verification. 5.2 Sample crushing equipment (applicable to near-infrared analyzers for measuring powder samples): The particle size distribution and uniformity of the crushed sample should meet the requirements of the near-infrared analyzer when establishing the calibration model, and the same preparation process should be used when using it as when establishing and verifying the calibration model. 6 Determination
6.1 Preparation before testing
6.1.1 Sample sampling and sub-sampling shall be carried out in accordance with the provisions of GB5491. 6.1.2 Arrange the samples and remove impurities and broken grains from the samples. 6.1.3 Perform instrument self-test according to the requirements of the near infrared analyzer (5.1) manual. 6.1.4 When in use, monitor the near infrared analyzer (5.1) at least once a day with the monitoring sample. The daily monitoring results should be tracked, and the measurement results of the same monitoring sample should be compared with the initial measurement results to ensure compliance with the provisions of 9.2. The preparation of monitoring samples shall be carried out in accordance with the provisions of Appendix A.
GB/T24901—2010www.bzxz.net
6.1.5 If the measurement results of the monitoring sample do not meet the requirements of 9.2, it should be stopped from use and reported to the network administrator or instrument supplier for adjustment or repair.
6.1.6 The temperature of the test sample should be controlled within the test temperature range specified in the calibration model verification. 6.2 Determination of whole corn samples
According to the requirements of the near infrared analyzer (5.1) manual, take an appropriate amount of sample and measure it with the near infrared analyzer, and record the measurement data. Each sample should be measured twice. After the first measurement, the measured sample should be mixed with the original sample to be measured, and then sampled again for the second measurement. 6.3 Measurement of crushed samples
According to the requirements of the near-infrared analyzer (5.1) manual, take an appropriate amount of corn sample, crush it using the specified crushing equipment (5.2), measure the corn flour sample using the near-infrared analyzer, and record the measurement data. Each sample should be measured twice. After the first measurement, the corn flour sample should be mixed with the original sample to be measured, and then sampled again for the second measurement. 7 Result processing and expression
7.1 In order to obtain valid results, the measurement results should be within the crude protein content range covered by the calibration model used by the instrument. 7.2 The absolute difference between the two measurement results should meet the requirements of 9.2. The average of the two data is taken as the measurement result, and the measurement result is retained to one decimal place.
7.3 If the absolute difference between the two test results does not meet the requirements of 9.2, two more independent tests must be performed to obtain four independent test results. If the range of the four independent test results (Xr-X) is equal to or less than 1.3 times the allowable difference, the average of the four independent test results is taken as the final test result; if the range of the four independent test results (Xx-Xmin) is greater than 1.3 times the allowable difference, the median of the four independent test results is taken as the final test result. 7.4 For abnormal measurement results of the instrument alarm, the obtained data should not be used as valid measurement data. The confirmation and processing of abnormal samples shall be carried out in accordance with the requirements of Chapter 8.
8 Confirmation and processing of abnormal samples
8.1 Confirmation of abnormal samples
8.1.1 The reasons for the formation of abnormal measurement results may come from the following aspects: The crude protein content of the sample exceeds the range of the calibration model of the instrument; the variety of the sample is very different from the variety of the sample set participating in the calibration of the instrument; the wrong calibration model is used;
- There are too many impurities in the sample;
- The sample is displaced during the spectral scanning process; the sample temperature exceeds the temperature range specified by the calibration model. 8.1.2 The causes of abnormal measurement results should be analyzed and eliminated, and then a second near-infrared measurement should be carried out. If the alarm still appears, it is confirmed to be an abnormal sample.
8.2 Treatment of abnormal samples
8.2.1 The crude protein content of abnormal samples should be determined according to the method specified in GB/T5511, and the samples should be sealed. 8.2.2 The situation of abnormal samples should be reported to the grain and oil near-infrared analysis network manager or instrument manufacturer to facilitate the upgrade of the calibration model in the future.
9 Accuracy and precision
9.1 Accuracy
The standard deviation (SEP) between the near-infrared measurement value and the standard value of the crude protein content of the verification sample set after deducting the systematic deviation should not exceed 0.30%.
9.2 Repeatability
GB/T24901—2010
In the same laboratory, by the same operator, using the same instrument and equipment, according to the same test method, in a short period of time, by re-sampling and re-sampling, the same sample is tested independently, and the absolute difference between the two test results obtained should not be greater than 0.3%. 9.3 Reproducibility
In different laboratories, by different operators, using different equipment of the same model, using the same test method, for the same corn sample, the absolute difference between the two independent test results of crude protein content (dry basis) should not be greater than 0.4%. 10
Test report
The test report shall include (but not limited to):
Calibration model name and number;
Applicable concentration range of the calibration model;
-Allowable temperature range of the calibration model;
For near-infrared analyzers that have been added to the grain and oil near-infrared analysis network, the name of the network, the time of joining the network, the number of joining the network, and the transfer time of the calibration model shall be provided;
For near-infrared analyzers that have not been added to the grain and oil near-infrared analysis network, the following information shall be provided:
Concentration range of the verification sample set;
Test temperature range of the verification sample set;|| tt||Verification unit and verification time;
Instrument model and serial number;
Monitored sample information;
Sample name and number;
Sample sampling method;
Sample preparation method;
Sample test temperature;
Sample measurement result;
Measurement method standard adopted;
When abnormal samples appear, the type of abnormal samples and relevant information on their treatment should be provided; Testing unit, tester and testing time; All details not specified in this standard or considered non-mandatory and that may affect the measurement results. GB/T24901--2010
A.1 Instrument
Appendix A
(Normative Appendix)
Preparation of monitored samples
Near infrared analyzer: Meet the requirements of 5.1 of this standard. 2 Preparation of monitoring samples
A.2.1 Sampling: Select a single variety of corn and take samples according to the method specified in GB5491. A.2.2 Sample pretreatment: Remove impurities and broken kernels from the sample, and divide the sample into about 500g per sample. A.2.3 Sample determination: Use a near-infrared analyzer (A.1) to determine the crude protein content (dry basis) of the sample. A.2.4 At least two monitoring samples should be prepared, one of which is kept for backup. A.3 Storage of monitoring samples
Samples should be sealed and stored in a ventilated, dry and cool environment. The shelf life should not exceed one year. A.4
Shelf life of monitoring samples
Each monitoring sample should be prepared again after 100 uses, or if it is infested with insects or contaminated. GB/T24901-2010
Printing date: September 21, 2010 F047
Copyright reserved. Infringements must be investigated
Book number: 155066·1-40229
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