Integrity test and analysis of filter of biological safety cabinet

The integrity of the filter is an important performance for the safe use of the biosafety cabinet, and it is also a problem frequently encountered in the process of highly concerned and tested by the operating user Through the test, analysis and evaluation of the filter integrity of the biosafety cabinet, it can provide for the research of the biosafety cabinet detection / calibration method and the development of the performance evaluation method of the biosafety cabinet, so as to ensure the safety and reliability of the biosafety cabinet in use [Key words] biosafety cabinet; filtration; test and analysis; aerosol; biohazardous particles background: the outline of national medium and long term science and technology development plan (2006-2020) and the 11th Five Year Plan of science and technology development of AQSIQ have clearly listed biosafety assurance in the field of the outline and its priority theme Therefore, the General Administration of quality inspection and Quarantine of the people's Republic of China has issued the scientific and technological plan project (Project No.: 2008qk285) of the research on the detection / calibration methods of biosafety cabinets to our institute; meanwhile, the quality and Technical Supervision Bureau of Guangdong Province has also issued the plan project (Project No.: [2008] 354-26) of the development of the local standards of the performance evaluation methods of biosafety cabinets to our institute It is mainly to establish the detection items and technical requirements of the biosafety cabinet, select the appropriate accuracy and accuracy, traceable detection standard device, and develop the standard method of performance evaluation of the biosafety cabinet Terminology analysis: biological safety cabinets (BSCs) are air purification safety devices to prevent harmful or unknown biological aerosols from escaping in the process of experimental operation Evaluation: the application of this method will make the detection methods and technical indicators of the biosafety cabinet standardized and unified, ensure the safety and effectiveness of the use of the biosafety cabinet, and at the same time, protect the safety of the environment It has a good application prospect and will produce great social benefits The air particle filter of biosafety cabinet, referred to as HEPA, is a dry filter with extended / wrinkled media filter membrane Its main purpose is to filter the dust and other particles in the air flowing into the working area of the safety cabinet, so as to ensure that the air in the safety cabinet reaches a certain degree of cleanliness; as well as to filter out the aerosol and other dangerous particles generated by the samples during the test operation, so as to protect the samples, avoid cross contamination between samples and prevent the biological dangerous particles from damaging the test operators At the same time, it can avoid the aerosol and other dangerous particles directly discharged into the environment, so as to protect the environment The filter membrane of the biosafety cabinet filter is a kind of disposable filter facility, which needs to be tested regularly If there is leakage, it must be replaced Otherwise, it will cause biological hazard Therefore, the effectiveness and integrity of biosafety cabinet filtration is an important performance index to measure the biosafety cabinet In order to complete the science and technology plan project of research on detection / calibration methods of biosafety cabinets approved by the General Administration of quality inspection and Quarantine of the people's Republic of China, as well as the task of establishing local standards of performance evaluation methods of biosafety cabinets by Guangdong Provincial Bureau of quality and technology supervision, and to obtain more test data Three different media (1.5% Ki, 0.9% NaCl, 10% C6H12O · 6H2O) were used for aerosol generation Through the use of aerosols produced by these three different media materials, the integrity of the biosafety cabinet filtration is tested in practice, and the analysis is based on the test data, so as to provide a reliable data basis for the safe use of the biosafety cabinet 1 Test instruments and methods 1.1 test instruments ⑴ aerosol generator is used to produce multi dispersed and high concentration aerosol, which can be produced by different materials (such as PSL, DOP, silicone oil, salt, sugar, etc.); the diameter of aerosol particles is between 0.01-2 μ M (2) sensor type of aerosol photometer: 90 ° light scattering instrument, 670 μ m laser tube; aerosol concentration measurement range: 0.001 ~ 20mg / m3; zero point stability: 24h ± 0.001 mg / m3 1.2 test method: turn on the fan and lamp of the biosafety cabinet, and remove the diffusion device and protective cover of the filter Place and turn on the aerosol generator, and guide the aerosol into the safety cabinet according to the aerosol introduction position set by the manufacturer, so that the aerosol is generated and evenly distributed in the upstream air flow of the filter If the manufacturer does not set the aerosol introduction position, the aerosol introduction method shall ensure that it is fully mixed in the airflow of the safety cabinet Open the aerosol photometer and sample the upstream gas stream containing aerosol in the filter The aerosol concentration shall not be less than 10mg / m3 Place the aerosol photometer detection port on the tested surface not more than 25 mm away from the test surface, and move it at a scanning rate of less than 50 mm / s, so that the probe scans the whole downstream airflow side of the filter and the edge of each combined filter, and the scanning route should overlap slightly Carefully test around the entire filter periphery, along the connection between the combined filter and the frame, and around the seal between the filter and the device For the safety cabinet with exhaust pipe, the scanning detection of exhaust filter cannot be carried out The detection of aerosol concentration in the gas flow downstream of the filter is to drill a hole with a diameter of about 10 mm on the pipe of the gas flow downstream, and insert the detection port with a hard tube photometer into the hole for detection 2 The test results were commissioned by an occupational disease prevention and control hospital in our city to test the integrity of the filtration of 12 biosafety cabinets in use in the hospital (including 4 of class II and 8 of class III) At present, the integrity test of biosafety cabinet filtration is mainly based on yy0569-2005 "biosafety cabinet" pharmaceutical industry standard, combined with European Union's en12469:2000 "biotechnology performance criteria for microbiological safety cabinets" and other technical requirements 3 Analysis and discussion from table 1, it can be seen that the consistency of test results is good when using 1.5% Ki, 0.9% NaCl and 10% C6H12O · 6H2O three different aerosol media materials Therefore, these three materials are more practical aerosol media materials for the measurement of the filter integrity and effectiveness of biosafety cabinets Among them, we think that 0.9% NaCl is not only easy to obtain and cheap, but also has less damage to the filter membrane According to yy0569-2005 "biosafety cabinet" pharmaceutical industry standard, the leakage rate of penetrant at any point of the filter integrity I-III scannable detection filter of biosafety cabinet shall not exceed 0.01%, and the leakage rate at the detection point of the non scannable detection filter shall not exceed 0.005% All 12 biosafety cabinets tested above are unqualified According to the actual situation of use and combined with other test results (such as bacterial culture method) and other technical literature reports, we adjusted the technical requirements for filter integrity of biosafety cabinet when formulating Guangdong Provincial Local Standard of performance evaluation method of biosafety cabinet as follows: the leakage rate of penetrant of scannable filter at any point shall not exceed 0.02%, not exceed 0.02% The leakage rate of the inspection points of the scannable filter shall not exceed 0.01% According to the technical requirements of this evaluation, 6 of the 12 biosafety cabinets tested meet the requirements, and the rest of the test results are out of tolerance to some extent, which does not meet the requirements Among them, the filter integrity of No 2 and No 4 cabinets is slightly out of tolerance; after investigation, the two cabinets have been used for three years, and the filter has not been replaced After replacing the new filter, the leakage rate is 0.01% The filter leakage rate of No.9 cabinet, No.10 cabinet and No.11 cabinet is between 10% and 30% These three cabinets have been used for about five years, and they have high frequency of use The filter has not been replaced Through inspection, the filter membrane of the filter is aged to a certain extent, and there are cracks on the upper part of the membrane During the subsequent leakage detection test of the cabinet, it is impossible to pressurize it to 500pa Therefore, it is judged that the three biosafety cabinets are unqualified, and the leakage rate is 0.01% after replacing the new filter The leakage rate of filter in No 12 cabinet is more than 60% This cabinet has been used for more than ten years, and the filter has not been replaced Through inspection, the filter membrane of the filter is seriously aged, and the membrane is not only full of cracks, but also damaged In the subsequent leakage detection test of the cabinet, it is unable to pressurize, so it is determined that the cabinet is seriously unqualified And because the cabinet model is old and there is no suitable filter replacement, the cabinet needs to stop using and be scrapped 4 Conclusion at present, due to the wide application of biosafety cabinets, there are many kinds of biosafety cabinets with different quality; and due to some quality defects, especially the lack of integrity and effectiveness of filtration, the leakage of infectious aerosols or toxic and harmful substances results in biological hazards Therefore, the application quality, safety and reliability of the biosafety cabinet have attracted the attention of the government and the community Our hospital often receives the user's demand for the quality detection of the biosafety cabinet Therefore, through the test of the filter integrity and effectiveness of the biosafety cabinet, it will play a very important role in the safety assessment, maintenance and maintenance of the biosafety cabinet, and it is also an important guarantee of biosafety Shanghai Sujing Industry Co., Ltd if you have any need, you can pass with us at any time Thank you very much for your support and look forward to cooperating with you Thank you & bestragard! Suing Jinghua