Standard operating procedures (SOPs) describe in detail the activities performed in the laboratory so as to:
provide uniformity, consistency and reliability in each of the activities performed in the laboratory;
reduce systematic errors;
provide training and guidance for new staff.
Standard operating procedures should be drawn up by specialized technical staff in the laboratory, revised by their immediate supervisor and approved by the Director of the laboratory.
Standard operating procedures should be prepared for general procedures, for example:
General: preparation of SOPs, correction of notes and documentation, preparation of protocols, reports.
Test systems: preparation of work areas, maintenance of work areas.
Laboratory operations: receipt, recording and labelling of samples, washing of recyclable apparatus, sterilization of material, storage of samples, labelling of materials and reagents, preparation of media and solutions.
Staff-related matters: training, handling of hazardous materials, laboratory safety, staffing of each laboratory subunit.
Reference materials: identification, characterization, handling, reception, storage, use.
Archives: maintenance, distribution and updating.
Equipment: regular calibration, cleaning, preventive maintenance.
Test methods: methods for processing and testing samples sent to a laboratory. They should closely follow the WHO recommended procedures and be drawn up according to the following the format shown in Figure 3.1.
An example SOP is shown in Figure 3.2. An example of a flow-chart for use with an SOP is shown in Figure 3.3.
Figure 3.1: Layout standard operating procedure
Code: This code will identify:
· the laboratory;
· the number relating to each procedure;
· the number that identifies the revisions, with 00 being used for the original document.
Objective: The aim of the procedure being described should be expressed clearly and concisely.
Scope: Name the operating unit that will apply the procedure, and the field of application of the procedure.
Definitions: The meaning of the principal terms used in the procedure should be stated.
General description: Each SOP should be drawn up clearly, without ambiguity, so that it can be understood by staff with and without experience. Each step for performing the activity that is regulated by the procedure should be described in detail. Flow diagrams may be used to complement the description.
Safety conditions: These should reflect the safety measures and conditions to be kept in mind for the correct execution of the SOP. Material Safety Data Sheets should be included for hazardous chemicals used.
Documentation: The form or protocol in which the data and measurements involved in the procedures should be recorded.
and documents: The references used to draw
up the SOP.
Figure 3.2: Example standard operating procedure
Title: Cell Culture Media Preparation
· The laboratory: name of laboratory
· The number relating to procedure: 3
· The number that identifies the revisions: 3.00 (original document), 3.01 would be first revision, 3.02 second revision, etc.
· Date: date of issue of this version
· Author(s): Dr . .
Objective: To describe Cell Culture Cell Media and its preparation for each of the two Cell Culture Cell Lines in the Cell Culture Laboratory.
Scope: This document contains the processes that are common to the Cell Culture Laboratory of the Polio Laboratory in the XXXXX Institute.
· RD refers to human Rhabdomyosarcoma cell line sensitive to poliovirus and many other enteroviruses.
· L20B refers to a cell line derived from a mouse L cell transfected with polio receptors that will selectively support the growth of Poliovirus but very few other enteroviruses.
· MEM: Eagles Minimum Essential Medium (Earles Salts base).
· PBS: Phosphate Buffered Saline.
Detailed account of activities of SOP.
Safety conditions: All safety guidelines will be followed throughout, including biosafety, chemical safety and disposal guidelines.
· Media type
· Catalogue number
· Lot number
· Date received
· Date prepared
· Volume prepared
· Prepared by
· QC results
· Expiry date of prepared media
· Date used
· Other comments
References and documents used to draw up SOP: WHO Polio Laboratory Manual.
Figure 3.3: Example standard operating procedure flow-chart
Each SOP should have the following on each page:
logo and name of the organization;
department or unit issuing the SOP;
signature of person who drew up the SOP with date (day, month and year);
signature of person who reviewed it with date (day, month and year);
signature of person who authorized it with date (day, month and year);
duration of validity;
date of review;
page number and total number of pages in the document.
Changes in a SOP should be implemented by specialized technical staff in the laboratory, revised by their immediate supervisor and approved by the Director of the laboratory. Any method that undergoes changes from the standard and official method should be validated before being put into practice, by comparing the following characteristics with the previous method:
accuracy: degree of correlation with the value achieved by the previous method;
precision: the variation of the results as represented by the standard deviation or the coefficient of variation;
sensitivity: capacity of the test procedure to record small variations between concentrations;
reproducibility: the precision of the procedure when it is performed under different conditions;
specificity: the degree of uniformity of the response to the substance in question;
robustness: ability to provide accurate and precise results under a variety of conditions.