Getting It Write? - - Chromatography Online
Getting It Write?

LCGC Europe
Volume 25, Issue 11, pp. 630-639

Ways to Write a Procedure

The typical way of writing a procedure is based on text. Here the procedure needs to be clearly written as an SOP is an instructional document. Therefore, instructions must be written in the form of 'do this' or 'do that'. The text needs to consist of short sentences that are written in simple, clear and directive language. Long and complex sentences that could be misunderstood should not be used.

The effective use of white space is important for the impact on the reader and to clearly separate each individual instruction. Rather than save paper and run all the text into large paragraphs, the text needs to be spread out to separate individual instructions that make up the procedure. There will therefore be empty lines between each instruction. Some companies number each instruction line and others don't, it is an organizational issue that probably goes back to when the quality system was first established.

Let us look at instructions that could be in a written procedure for a laboratory. In Table 2 we have sample preparation instructions. They are written in a clear simple style: do this or do that. However, look at Table 2 to see the differences in the use of white space. In both columns are the same instructions for the sample preparation of samples for metals analysis by atomic absorption. The instructions in the left hand column are all together and it is difficult to read or follow the procedure in the laboratory. This series of instructions is what you would see in a scientific publication of a method but, in my view, is not appropriate for a laboratory procedure.

Table 3: Procedure written using a process flow diagram with a process description.
In the right hand column of Table 2 are the same instructions but they are broken up into a series of bullet points to illustrate the effective use of white space. The individual instructions can be easily followed and is how written procedures for either analytical methods or work in the laboratory could be set out as.

Is everything good? No. Look in Table 2 at column 2 and the fourth bullet point. Here it states either digest the same for 110 C until it goes brown (all cooking is just good chemistry!) or if you are lazy and want to go home early then leave the samples at 40 C overnight. Why the two options? Has the method been validated to cope with either approach? The instructions for this step should be a little clearer in my view.

Can we make the procedure any better? Yes, by the use of process flow diagrams, an example of which is shown in Table 3. The left hand column shows a process flow diagram of the procedure with each stage of the process shown as a box in the process flow. The same text from Table 2 has been inserted in the right hand column without the bullet points and positioned next to the appropriate process flow activity to add detail to the process flow. So this version of the procedure has a picture to give the overview and the text to provide the detail.

We can develop this version of the procedure further by adding another column called 'responsibilities' on the right, to define who does each step and where the hand over from one person to the next can be described as well.

How Long Should a Procedure Be?

This is never an easy question to answer but as short as possible is the best answer I can give. If necessary, have an overview procedure or guideline and then break a process down into a number of smaller ones that will be read and used, rather than filed and forgotten. My ideal SOP length would be in the region of 3–5 pages including diagrams, the shorter the better providing that quality is not impacted.

How Do I Know You Followed the SOP?

In some quality systems there is the need to provide evidence that the procedure has been followed. In Chapter 4 of EU GMP (1) on Documentation there is the requirement for instructions (to perform a task, e.g., SOP) and records which provide evidence of various actions taken to demonstrate compliance with instructions. So records are the result of procedures being followed. For an analytical procedure this is relatively easy as it's the sample preparation and analysis records that can be on paper or in electronic format that demonstrate that the procedure was followed. For other procedures, the author needs to think what evidence is generated by the procedure to provide evidence of compliance.

Training: Read and Understand or Assess Competence?

A classic method of training is the read and understand, where the procedure is distributed, either in paper or electronically, to the analytical scientists who are going to use the procedure. Each person reads the procedure and then self-certifies that that they have read and understood the procedure. Is this acceptable? It depends. If it is a new analytical procedure, then probably not — you will want to have a better way to assess if an individual can perform the method and get acceptable results.

If it is an update of an existing method with minor modifications then 'read and understand' is usually acceptable. However, the training world is moving from a 'read and understand' world to demonstrating an understanding or competence depending on the nature of the procedure involved,


In this article we have looked at writing procedures which demonstrate how to perform an activity in a laboratory. Simple sentences with specific directions are needed with a good use of white space to aid readability. Diagrams will help understanding and roles and responsibilities need to be defined within the procedure.


(1) Principle of Chapter 4 on Documentation, EU Good Manufacturing Practice, 2011

"Questions of Quality" editor Bob McDowall is Principal at McDowall Consulting, Bromley, Kent, UK. He is also a member of LCGC Europe's Editorial Advisory Board. Direct correspondence about this column should be addressed to "Questions of Quality", LCGC Europe, 4A Bridgegate Pavilion, Chester Business Park, Wrexham Road, Chester, CH4 9QH, UK or e-mail the editor Alasdair Matheson at


blog comments powered by Disqus
LCGC E-mail Newsletters
Global E-newsletters subscribe here:



Column Watch: Ron Majors, established authority on new column technologies, keeps readers up-to-date with new sample preparation trends in all branches of chromatography and reviews developments. LATEST: When Bad Things Happen to Good Food: Applications of HPLC to Detect Food Adulteration

Perspectives in Modern HPLC: Michael W. Dong is a senior scientist in Small Molecule Drug Discovery at Genentech in South San Francisco, California. He is responsible for new technologies, automation, and supporting late-stage research projects in small molecule analytical chemistry and QC of small molecule pharmaceutical sciences. LATEST: HPLC for Characterization and Quality Control of Therapeutic Monoclonal Antibodies

MS — The Practical Art: Kate Yu brings her expertise in the field of mass spectrometry and hyphenated techniques to the pages of LCGC. In this column she examines the mass spectrometric side of coupled liquid and gas-phase systems. Troubleshooting-style articles provide readers with invaluable advice for getting the most from their mass spectrometers. LATEST: Radical Mass Spectrometry as a New Frontier for Bioanalysis

LC Troubleshooting: LC Troubleshooting sets about making HPLC methods easier to master. By covering the basics of liquid chromatography separations and instrumentation, John Dolan is able to highlight common problems and provide remedies for them. LATEST: How Much Can I Inject? Part I: Injecting in Mobile Phase

More LCGC Columnists>>

LCGC North America Editorial Advisory Board>>

LCGC Europe Editorial Advisory Board>>

LCGC Editorial Team Contacts>>

Source: LCGC Europe,
Click here