SOP for Monitoring UV Light Efficiency in LAF and Pass Box : Pharmaguideline

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SOP for Monitoring UV Light Efficiency in LAF and Pass Box

Standard operating procedure to monitor the performance of UV light installed in LAF and pass box.


To lay down a Procedure is to provide guidelines for monitoring UV Light Efficiency LAF & Pass Box.


This procedure is applicable for all UV Light units installed in microbiology section.




Head - QA & QC


5.1 Prepare SCDA medium as per SOP for preparation of culture media.
5.2 Aseptically pour approximately 15–20 ml of sterile molten cooled (40-45ºC) SCDA agar into sterile 90 mm Petri plates under LAF.
5.3 Allow the media to solidify the plates under LAF, after solidification label all the plates with the name of media, preparation batch No. and date of preparation.
5.4 Invert and incubate the plates at 30 to 35ºC for 24 hrs in BOD Incubator. After incubation physically inspect the plates for any contamination (Macroscopic growth of evidence), if there is contamination discard the plates as per SOP for Destruction of Microbial waste by Autoclaving
5.5 After pre-incubation, transfer 1-1 ml of not less than 105 cfu per ml culture of Bacillus subtilis to two SCDA Petri plates & spread the colony using a sterile spreader. (Prepare 106 cfu per ml suspension of Bacillus subtilis as per SOP of Disinfectant Efficacy Test.
5.6 Now wrap one Petri plate containing Bacillus subtilis in Aluminium foil and do not wrap other Petri plate. Now transfer both the Petri plates in LAF. Open the lid of unwrapped Petri plate.
5.7 Now switch on UV light for 30 minutes.
5.8 After 30 minutes exposure, switch off the UV light & close the lid of unwrapped Petri plate.
5.9 Incubate both the Petri plates in the incubator at 30-35ºC for 24-48 hours.
5.10 Prepare positive control by streaking Bacillus subtilis culture and negative control as it is without streaking.
5.11 Apply the same procedure for UV Light of other LAF & Pass Box. For checking Efficiency of UV Light of LAF of Sterility Room, do not perform the test in Sterility Room. For the test, the UV light of Sterility LAF should be fitted to MLT or BET LAF.
5.12 After incubation observe the plates for the total bacterial count. Record the results on UV Light Efficiency test record.
5.13 Precaution
5.13.1 Switch on the UV light after exposing the plates on the work station of the LAF.
5.13.2 Switch off the UV light before collecting the plates.
5.14 Frequencies
5.14.1 Once in the month
5.15 Limits/ Acceptance Criteria
5.15.1 There should not be growth in unwrapped Petri plate & there should be growth in Petri plate wrapped in Aluminium foil. Positive control should show growth and Negative control should not show any growth.


SOP: Standard Operating Procedure
QA: Quality Assurance
QC: Quality Control
NA: Not Applicable
IPA: Isopropyl Alcohol
LAF: Laminar Air Flow
cfu: Colony forming unit
SCDA: Soybean casein digest Agar
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6 comments: Post Yours! Read Comment Policy ▼

  1. What is the reference of the plate exposure for 30 minutes ? In the book of Standard Method for the examination of Water and Waste water in APHA, there is stated that 3 minutes should be exposed the plate under UV Light.

  2. Generally the UV light of LAF and pass box is kept ON before start the work therefore the plate are exposed for 30 min. If you keep the UV light ON for 3 min then you should expose the plates for 3 min. during the monitoring of UV light efficacy test.

  3. Hello, may I ask that 5.5 transfer 1-1 mL of not less than ...., is that 0.1-1mL or actually other volume?

  4. Transfer 1 ml to each of two petri dishes.

  5. may I ask what is the log reduction if i follow this procedure and how to obtain it please

    1. Anonymous01 September

      I have a question.some UV lights on only for 30 seconds or 1 minute.Can I expose plates for 30 seconds or 1 minute?


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