Application Notes

8 Steps to Mapping a Stability or Environmental Chamber

Periodic mapping of temperature or humidity inside environmental chambers is important to ensure uniform storage or test conditions. This mapping is an important part of the validation process to ensure the equipment meets required performance criteria.

This application note provides eight basic steps to follow when using Veriteq VL-Series Validatable data loggers to map an environmental chamber.

• Step 1 -- Write a Plan
• Step 2 -- Ensure proper equipment & documentation
• Step 3 -- Confirm data logger operation
• Step 4 -- Set up the data loggers
• Step 5 -- Place the data loggers
• Step 6 -- Periodically check the progress
• Step 7 -- Retrieve and store the data
• Step 8 -- Report the findings

Step 1 -- Write a Validation Plan

As with any important task, it helps to think through the chamber mapping process completely before diving in. Write out what you want to obtain, an outline of your methods, and any barriers you may anticipate.

Some key questions to consider are:

• How many data points do you need to monitor/map?
  Typical numbers of units that many of our customers use to map small chambers are:
  • Nine (9): Two layers of four loggers each (one near each corner) plus one logger in the center, or
    
    
  • Fifteen (15): three layers of four loggers (one near each corner) plus one logger in the center at each level, or
    
    
  • Four or five loggers on each shelf.
    
    
• Where will each data logger be placed? Spacing the loggers in an evenly distributed grid is essential.
  
  
• Will the mapping take place with the chamber empty, as for an Operation Qualification (OQ), or full of product , as for a Performance Qualification (PQ)? For many companies, both tests are important. Consider how OQ and PQ might affect your process and make a note of that.
  
  
• Are you mapping air temperature inside the chamber, or will probes be needed to track interior product temperatures? Tracking interior product temperatures, such as the temperature inside a solution bottle is sometimes considered more meaningful as it insulates the data against minor disturbances such as periodic door openings and closings.
  
  
• What parameters will you measure? Should the chamber be mapped for temperature only? Or temperature AND relative humidity? If there is any plan to store products in the chamber with humidity sensitivities, then the chamber should be mapped for relative humidity as well as temperature.
  
  
• How frequently will you take readings? Typical sample rates are once every minute or once every five minutes.
  
  
• How long will the mapping study be? Typical study lengths are 24, 48, or 72 hours. Occasionally facilities map for one week, one month, or even longer.
  
  
• When will the mapping study start? When will it end? Determining your test schedule will allow you to set all data loggers to simultaneously start and stop collecting data at the same time.

Many of these questions may already be answered by your past practices, protocols, or SOPs.

Step 2 -- Ensure the Equipment and Documentation are in Place

In a GMP environment it is essential to ensure that the equipment being used to perform any chamber qualification is not only appropriate for the job but in good working order. Two questions to keep in mind for this purpose are:

• Have the data loggers been validated for this type of application? Veriteq Instruments provides an IQ/OQ validation protocol expressly for this purpose.
• Are the data loggers currently in calibration? Check the Calibration Certificates (see example) or use vLog software to check the calibration date information stored in each data logger's memory.

Step 3 -- Confirm the Operation of the Data Loggers

Before using the data loggers, check to see that they are operating correctly and have not been damaged. You may have an SOP that covers this type of check. If not, there are several ways you can ensure proper operation. For example, if the data loggers have been stored together and set to "wrap" (take readings on a continuous "sliding window" basis), you can transfer the information collected by the data loggers to your PC and compare the readings from the various data loggers. If the data loggers have not been stored together, you could place the data loggers side by side for a short time and then compare the readings. For more information on other possibilities, refer to Making Interim Temperature and Humidity Calibration Checks.

Step 4 -- Set Up the Data Loggers

• Use Veriteq vLog software to set the start and stop times, the sample interval, and the logger description
• vLog's delayed start time feature allows sufficient time for you to set up and place all the data loggers, and for the chamber to stabilize, if desired, before data collection begins
• Configuring the same start and stop time for all the data loggers enables you to synchronize their start and stop times and eliminate the collection of extraneous data
• Set a sample interval that is appropriate to your application. Again, a typical "safe" sample interval might be once per minute
• Set a meaningful data logger description for each of the data loggers. For example, you might use this feature to give each data logger an ID that describes its location in the chamber

Step 5 -- Place the Data Loggers

Place the data loggers in the chamber according to your validation protocol, or according to a diagram or grid you have set out. Some customers choose to photograph the interior of the chamber to show both logger and product placement.

Be sure to also place a data logger outside the chamber to monitor ambient temperature, or both ambient temperature and relative humidity. Failure to do so may invalidate the results as exterior temperatures can sometimes significantly influence interior performance. Place this outside data logger away from areas of undue temperature influence such as an outside wall, a heat-generating piece of equipment, near a window, or in a high traffic area.

Step 6 -- Periodically Check the Progress (optional)

It's a good idea to check your study results periodically to ensure that the mapping is progressing as expected. As an example, your protocol may call for you to establish when the temperature in the chamber stabilizes or to verify operation throughout the course of the study.

Using a Veriteq "flat cable", you can periodically check the data for one data logger without disturbing the chamber.

Step 7 -- Retrieve and Store the Data

When the study is complete, use Veriteq vLog software to transfer the data from each data logger to your PC.

vLog software enables you to customize the filename format to make it easy to track files and relate them to your deployment. It is recommended that the software be set to automatically include the following information in each file name: serial number of the data logger, time and date of the data download, and user description of the data logger.

Veriteq vLog files are tamper-proof and secure, and meet the FDA's electronic record requirements of 21 CFR Part 11. Each file is uniquely identified, allowing users to relate each printout to the original data logger files.

Step 8 -- Report the Findings

The results of your mapping study can be reported in several different ways:

• All data logger files can be plotted on one graph to show the variances in different parts of the chamber.
• A "raw data" printout of all readings and associated times and dates can be printed to support the above graph
• Data can be exported to Excel to facilitate further reports

For more information on using Veriteq data loggers to validate environmental chambers, please contact Veriteq.