Header Ads Widget

SOP for Air Settling Plates Technique

To inspect the cleaningness of working environment in different plant locations using settling plates (Passive air sampling).

LFH (Microbiology Department)
Weighing booth - Raw material sampling booth.
Microbiology laboratory
Dispensing room
Solid manufacturing areas:
  • RM stagnant room - oven drier room - fluid bed dryer room - granulation room - blending room - tablet compression room - capsule filling room - coating room - blistering room - sorting room - central packaging room.

Microbiologist in Microbiology Department

Settle Plate Method
The principle behind this method is that the bacteria carrying particles are allowed to settle onto the medium for a given period of time and incubated at the required temperature. A count of colonies formed shows the number of settled bacteria containing particles.


Preparation of sedimentation plates (settle plates).
Pour approximately 25 ml of sterile nutrient agar or trypton soy agar into sterile Petridis (90mm in diameter), allow to solidify.
Incubate the plates, inverted, for 24 hours at 30-35°C to verify their sterility.
Label the base of plates (the part containing the media) with the label No., provided with the name of the department, location No., date, time, previous (in case of rest) or current (in case of operation) product name, batch No. and name of sampler.

  • Transfer the plates into the area/room where you want to test the cleaningness of working environment.
  • Wear the provided gloves.
  • Place plates at table/stand height if possible or another appropriate position.(Work surfaces must be disinfected before and after use).
  • Raise the lids of plates to expose the surface of the medium, rest the lid on the very edge of the plate so that the entire agar surface is completely exposed, take care not to put fingers on plates.

  • Leave plates exposed for four hours at all locations.

  • Refer to the checklist of settling plates to find out the sampling locations of plates. Record the date and time (exposure time) of the collected samples in the same checklist.
  • After exposure: replace lids of plates, and carefully place them back in a protective bag to avoid breakage before returning to the microbiology lab.
  • Relocate the plates to the microbiology department with the following information:
  1. Date and Time of sampling.
  2. Department name.
  3. Location/room name
  4. Product name – Batch No.
  5. Name of sampler.
  • Record samples in the log book of environmental monitoring samples receipt and the log book of environmental monitoring results.

Incubation and detection of pathogens.
  • Incubate the plates at 30-35°C for 48 hours, Count the developed colonies using the colony counter and record the average results in the results log book.
  • Wash out the surface of the plates using 5 ml sterile saline solution
  • Refer to SOP to test the previously obtained culture for the presence of Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans, Record the results in the results and certificate of analysis. 
  • Send the original to the QA Department, a copy to the production directorate and keep another copy in the Microbiology department.
  • Record the results which exceed the action limit on the Deviation log book and issue a non conformity report to the Quality Assurance Department for necessary actions.

Frequency and specifications:



(Average count



(Average count



LFH (Microbiology Department)


> 1 cfu/4 h


Weighing booth

> 40 cfu/4 h

> 50 cfu/4 h

Raw material sampling booth

(Microbiology laboratory)

> 40cfu/4 h

> 50 cfu/4 h

Solid manufacturing areas:

RM Stagnant Room

Oven Dryer Room

Fluid Bed Dryer Room

Granulation Room

Blending Room

Tablet Compression Room

Capsule Filling Room

Coating Room

Blistering Room

Sorting Room

Central Packaging Room.

> 80 cfu/4 h

> 100 cfu/4 h


Dispensing room




  • All locations should be free from P. aeruginosa, S. aureus and C. albicans and fungi.


Revision History

Post a Comment