6 Laboratory Quality Assurance System

6.1 Laboratory Construction
In China there are altogether 8 reference laboratories for residue detection and 31 approved laboratories under AQSIQ, and 22 national key laboratories, 43 regional central laboratories, 6 routine laboratories are involved in animal disease detection.
There are 2 reference laboratories for residue detection and 32 approved laboratories under MOA.

6.1.1 reference laboratories
Responsibilities of Reference Laboratories: setting up and coordinating residue analysis methods and standards; assisting the competent authorities in establishing and carrying out residue monitoring programs; participating in international comparative tests and performance tests; organizing regular comparative tests and performance tests; collecting and transferring information on international residue monitoring; offering domestic or international training programs for analytical staff to improve their analytical skills.

6.1.2 Approved laboratories
Responsibilities of Approved Laboratories: presenting assigned testing results; strictly carrying out designated standards, methods or detection limits for residue testing; participating in comparative tests organized by reference laboratories; proposing to reference laboratories on improving testing methods.

6.2 Management of Laboratory Quality
All laboratories have been accredited by Laboratory Accreditation Committee and have adequate quality control documentation in accordance with ISO/IEC-17025-1997.
The laboratories are finely staffed with employees who have been trained on residue analysis and are familiar with international standards and practices. The laboratories are also equipped with adequate facilities and documentation to complete assigned analysis projects. The laboratories have good administrative organizations, own latest CRMs and related information, and possess sufficient data processing abilities, are able to rapidly submit statistical data and other information to the competent authorities and at the same time, notifying other laboratories.

6.3 Laboratory Testing Methods

6.3.1 Routine Methods of analysis
Laboratories use testing methods in accordance with the laws of inspection and quarantine and the requirements of the national residue monitoring program. Routine methods of analysis must be verified in the laboratory and can be used for the purpose of screening and confirmation.

6.3.1.1 Screening Methods: used for the screening of one kind or one class of compounds; the sensitivity can meet the requirement of residue detection. The methods must be suitable for samples of large numbers for potential positive results; specifically designed to avoid false negative results.

6.3.1.2 Confirmatory Methods: used for confirmation, which provides full or complementary information for positive results, specifically designed to avoid false positive results. The sensitivity can satisfy the requirements for residue detection.

6.3.2 Interpretation of Results

6.3.2.1 Positive Results: if the presence of a substance that must not be found in the sample is confirmed, the result is regarded as "positive". For substance with an established maximum residue limit, the result of the analysis is considered as ‘positive’ in case the determined content of the identified compound in the sample is higher than the MRLs (in any calibration).

6.3.2.2 Negative Results: if a substance that must not be detected in the sample has proved to be out of existence, the result is regarded as "negative". For substances with established MRLs, the result is regarded as ‘negative’ in case the content of the compound in the sample is lower than the MRLs.

6.3.3 Choosing of Methods of Analysis

6.3.3.1 Relevant Chinese national standards (GB) or Chinese industrial standards (SN)

6.3.3.2 Recognized standard methods, for instance, ISO methods

6.3.3.3 Standard Operational Practices (SOP) authorized by competent authorities or institutions.

6.3.4 Quality Control

6.3.4.1 Analytical methods must be approved or validated thoroughly before put into use;

6.3.4.2 It has been stipulated that only those who have been examined and qualified can handle sample analysis, calculation, recording and checking of results;

6.3.4.3 Use control samples, including certified reference materials (CRM), or other laboratory reference materials calibrated by the standard substances recognized internationally. Samples analyzed each time should be paralleled with quality control samples

6.3.4.4 Recovery, linearity and calibration curve should be checked by spiked samples (with target component or internal standard).

6.3.4.5 Main testing facilities should meet the requirements of analytical methods, and be verified and maintained regularly.

6.3.4.6 Data calculation should be presented in detail. The results must meet statistical quality control requirements.

6.3.5 Participating in Comparative Tests and Performance Tests
Although there are few international tests on residue testing performance, quite a lot of CIQ laboratories participated in international comparative tests and performance tests in recent years: 35 laboratories have been accredited by Japanese Ministry of Welfare and Labor; 9 laboratories from Zhejiang and Shanghai took part in tea residue detection performance tests organized by TPA and have been accredited by European Tea Committee; Laboratories from Liaoning, Zhejiang and Shanghai participated in performance tests organized by APLAC; commodity inspection research institutes in Qinhuangdao and Dalian participated in AOAC testing method co-experiment (on items of Clopitol, pyrethroids, etc.) In the meantime, State Laboratory Accreditation Committee frequently organizes nationwide laboratory performance tests, blind sample tests and comparative tests.