Home > News

How to conduct interim verification on standard samples?

How to conduct interim verification on standard samples?

1、 What is the verification during the standard substance/standard sample period

According to the prescribed procedures and schedule, the operation is carried out within the validity period of a standard substance/sample to determine whether the RM has remained in its original state during use.

2、 Interim verification requirements

The laboratory should determine the verification method, cycle, and determination of verification results in the form of documents, and keep records. In most cases, verifying the accuracy of RM characteristic values is very difficult and unrealistic.

3、 Verification content during the period

3.1 Period verification of CRM

3.1.1 Unopened CRM

For unopened CRM, administrators or users should verify whether the CRM is within its validity period and whether it is properly stored according to the storage conditions and environmental requirements specified on the CRM certificate. If the requirements are met, the CRM does not need to use other methods for interim verification.

3.1.2 Opened CRM

For CRM that has been opened, the laboratory should ensure that it is used within its validity period. If the CRM is allowed to be used multiple times within its validity period, ensure that its usage and storage meet the requirements specified on the certificate. When necessary, root requirements. Based on its stability characteristics, frequency of use, changes in storage conditions, and reliability of measurement results, verify the stability of its characteristic values using relevant verification methods.

3.2 Periodic verification of non certified reference materials/standard samples

Non certified reference materials/standard samples include certain pure substances purchased from external sources, quality control samples, standard solutions prepared internally in the laboratory, standard gases, etc. It is necessary to regularly select the verification method in 3.3 to verify the stability of their characteristic values, and use the determination method in 3.5.1 to determine whether the verification results are qualified.

3.3 Verification methods during the period

During the verification process, one of the following methods can be adopted:

a) Test laboratory quality control samples that are sufficiently stable and have an uncertainty similar to the verified object;

b) Compare the measurement values with CRM at the same level or with similar uncertainty;

c) Send to qualified testing/calibration institutions for confirmation;

d) Conduct inter laboratory quantity comparison;

e) Test samples that have recently participated in the ability verification and obtained satisfactory results;

f) Use quality control charts for trend checking, etc.

3.4 Frequency of verification during the period

The laboratory can monitor the stability of RM through daily quality control results and quality control charts. If there is no quality control data, the frequency of intermediate checks can refer to the following suggestions:

3.4.1 Periodic verification frequency of CRM

Unopened CRM shall undergo a verification in accordance with the requirements of 3.1.1 before use.

CRM that has been opened but has not been used up or can be reused, as required by the certificate