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How to Write an Effective Lab SOP 

Clearly document how lab activities are best accomplished

Scott D. Hanton, PhD

Scott Hanton is the editorial director of Lab Manager. He spent 30 years as a research chemist, lab manager, and business leader at Air Products and Intertek. He earned...

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Labs benefit from documenting how to complete activities, especially those that are either very important or relatively common. Standard operating procedures (SOPs) are an excellent tool to guide staff toward completing these activities efficiently and correctly and are part of an effective quality management system. Having well-written SOPs will enable faster training of staff to new activities and improve compliance within the lab.

SOPs effectively document a wide range of lab activities. They are often grouped into two broad categories: scientific processes and quality requirements. 

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Examples of scientific processes might include things like:

  • How to measure pH of a liquid sample
  • How to determine the concentration of an analyte by liquid chromatography (LC), or
  • How to operate a Fourier Transform Infrared (FTIR) instrument. 

Examples of quality requirement SOPs might include things like:

  • How to calibrate the flow rate of an LC
  • How to document measurement uncertainty, and
  • How to validate a newly developed analytical method.

The keys to writing an effective SOP are to document the steps clearly and concisely to properly complete the activity in language that is readily understood by the people expected to do the work. One approach that works well is to have a person new to the activity take notes while an experienced staff member completes the work. Those notes can be reviewed by experienced staff and become a rough draft for the specific SOP. Encourage the new person to ask questions and provide sufficient time for the notes to be taken and discussed throughout the planned activity.  

To effectively create a new SOP (or review an existing one) please consider the eight different actions below.

What is the purpose of this SOP?

The first paragraph of the document needs to clearly state what following the steps in the SOP will accomplish, when it should be used, and why this procedure should be followed. It also needs to define any important assumptions under which this procedure is valid. 

What activity does the SOP describe?

The title of an SOP needs to be simple and straightforward. It needs to be easy for staff to understand which SOP they will follow to accomplish a specific goal. As the lab produces more SOPs to cover different aspects of their technical work, clearly distinguishing the differences in the title becomes more important. The title can contain the common jargon of the lab—it just needs to be clear and obvious to those who are expected to use it.

If there are closely related SOPs in the lab—like different SOPs to analyze different kinds of samples by FTIR—these need to be reflected in the title.

Who has roles in this SOP?

The next portion of the SOP needs to clearly define who has responsibilities under this procedure and what those responsibilities are. For example, an SOP relating to an analysis by LC might state that the operator will be responsible to check for system suitability, that the instrument is operating properly, and to run the specified analyses. The SOP would then document who needs to review the results and sign off on the work. Effective SOPs also document how issues can be escalated to rapidly resolve problems.

When was this SOP written, by whom, and who approved it?

The document needs to clearly establish who wrote the SOP and when the procedure was written. If questions arise, it is important to know who developed the procedure to get unexpected questions resolved. 

For compliance, it is important to understand the approval process for the SOP. The chain of approval should be documented to ensure that only fully approved SOPs are active in the lab.

When will the SOP be reviewed?

Processes around the lab will change with time and further development. Encourage SOP owners to take the time to make updates as new information is learned and improvements to the procedure are developed. Make updating and improving SOPs part of the lab’s culture. 

Over time, all SOPs will need to be reviewed, updated, and re-approved. List the timeframe for the next review of the SOP and who will have the responsibility for the review and any potential updates. Ensure the review date is easy to find so that lab staff don’t continue using an expired SOP.

What are the steps to accomplish the goal? 

The body of the SOP will document the specific steps required to achieve the purpose of the activity. These steps need to be granular enough that someone learning the activity can follow them safely and successfully, but not so detailed that the purpose gets lost in too many words. Having experts review the notes of beginners is a good way to find this balance.

The steps of the activity need to start at the normal beginning of the process and carry the operator through to the normal end of the activity. For many lab activities, there may be a series of SOPs to be followed to fully complete the process. For example, for an analytical measurement, the process may start with a quality SOP around sample identification and login, followed by an SOP on sample preparation, then sample analysis on a specific instrument using a specific method. Once data is acquired, the operator may then follow a series of SOPs around data analysis and calculations, measurement uncertainty, and finally, reporting and quality assurance review.

How is the procedure done safely?

Some labs will include safety information directly in the SOP while others will have a separate document focused on the safe operation of the activity. It is vital that safety and risk information are clearly delivered to all staff responsible for working in the lab.

If the safety information is in a separate document, it must be referenced in the SOP. If the safety information is included in the SOP, it is important to point out all of the significant risks and provide guidance to performing the actions safely. This should include the appropriate use of the hierarchy of safety controls and any required personal protective equipment.

What other information is important?

Include a references section in the SOP. It can include related information that was used to create the procedure, other related SOPs that may be needed, and any additional safety information pertaining to these activities. The references make it easy for lab staff to find related information that helps them perform this procedure better and safer.