SOP and Protocol Management
TL;DR
A standard operating procedure (SOP) is a written, approved set of instructions for doing a routine lab task the same way every time, such as calibrating a balance or receiving a sample shipment. As a controlled document it has an owner, a version, an approval and an effective date, and only the current version belongs at the bench.
A standard operating procedure (SOP) is a written, approved document that tells trained staff how to carry out a routine task the same way every time, whether that is calibrating a pH meter, running a plate reader, receiving a sample shipment or decontaminating a biosafety cabinet. It is a controlled document with an owner, a version, a documented approval and an effective date, and only the current approved version should be in use at the bench.
SOPs came into lab science largely through regulation. FDA introduced the Good Laboratory Practice regulations in the late 1970s, after inspections turned up badly run toxicology studies, and written SOPs became a requirement for nonclinical safety studies. GMP and clinical labs have similar rules. Many academic core facilities and biotech research groups now keep SOPs for a plainer reason: so a method doesn't live only in the head of whoever trained the last person.
SOP and protocol get mixed up a lot. The SOP tells you how to run the HPLC. The protocol, or study plan, tells you how to use the HPLC to answer one research question, and it usually points to several SOPs for the routine steps. Below the SOP sit work instructions, which cover a single narrow step in more detail.
Written SOPs are a regulatory requirement for studies conducted under GLP. 21 CFR 58.81 requires a testing facility to have written SOPs that management is satisfied are adequate to protect the quality and integrity of study data, and then gets specific. Each laboratory area must have the SOPs for its procedures immediately available, and deviations from them have to be authorized by the study director and documented in the raw data. The facility also keeps a historical file of every SOP and all its revisions, with the revision dates.
The OECD Principles of Good Laboratory Practice set equivalent expectations. Outside GLP and GMP, SOPs are good practice and not a legal obligation, though sponsors and collaborators often ask to see them before they rely on a lab's data.
The person who does the task most often, in numbered steps, with the exact volumes and incubation times the bench really uses. Start with the procedures where variation does the most damage: instrument calibration, sample receipt and storage, preparation of shared reagents, and waste disposal.
If two people thaw cells two different ways, the variability lands in the data and nobody can trace where it came from. A written SOP turns "Dave showed me when I started and I've done it that way ever since" into a method a new hire can read before shadowing anyone and an auditor can check. But an SOP describing an idealized method documents a gap between procedure and practice, and auditors look for exactly that gap.
Most labs run SOPs through the same lifecycle:
Give each SOP an ID, a version number, an owner and an effective date, and keep superseded versions in an archive instead of deleting them. GLP inspectors and sponsor auditors ask what method was in force on a particular date, and the archive is how you answer. For a longer guide, see Mastering Standard Operating Procedures in the Lab.
In IGOR, SOPs are written in the SOP Generator, which has a formal review and approval workflow with electronic signatures, and a Super Admin sets the number of required approvals for the whole organization. Only shared SOPs can be attached to a notebook entry. Attaching one creates a copy, so the master SOP is never altered and the copy keeps its own version history inside the entry. Outdated SOPs are archived to keep them out of circulation.
Paper copies and equipment tend to outlive the document they belong to. A printed copy of version 3 stays taped inside the tissue culture hood long after version 5 changed the trypsin incubation time. Or the lab replaces its centrifuge, the SOP still describes the old one, and the manufacturer's quick-start guide becomes the working method while the SOP sits on the shared drive.
Each of those makes one question hard to answer later: which version of the SOP was in effect when this experiment was run? Periodic review catches some of it. Recording the SOP version in the notebook entry that used it catches more.
An SOP describes how to carry out a routine task the same way every time, while a protocol describes one specific experiment or study and its objective. A protocol usually refers to several SOPs for the routine steps inside it.
Most labs review SOPs every one to two years, and sooner when equipment or methods change. The FDA GLP regulations don't set a fixed interval, so the frequency is defined in the lab's own SOP on document control. Missed periodic reviews are a common audit finding.
A lab SOP usually includes a title and ID, purpose and scope, responsibilities, required materials and equipment, safety precautions, numbered procedure steps, acceptance criteria, references, and a revision history with dates. Regulated labs also record the approval signatures and the effective date.
The steps should be specific enough that a trained person could follow them without asking anyone.
Record the deviation when it happens, in the notebook entry or on a deviation form, with what you did differently and why. Under GLP, deviations from SOPs must be authorized by the study director and documented in the raw data. If the same deviation keeps coming up, the SOP probably needs revising.
SOPs need a documented approval, and when that approval is captured electronically for FDA-regulated work, the electronic signature has to meet 21 CFR Part 11. Outside regulated work, any traceable sign-off will do. In IGOR, SOPs in the SOP Generator are approved through a review workflow with electronic signatures compliant with 21 CFR Part 11.