Example SOP for QC Reagents and Volumetric Solutions

In short: This illustrative SOP template covers the lifecycle of laboratory reagents and volumetric solutions used in QC. Use approved preparation and standardization methods, identify each solution, document its preparation and suitability, and assign storage and retest or expiry conditions using justified data. Adapt the safety and validity controls to the material, method and site.

1. Purpose

To describe a site-adaptable system for receiving, storing, preparing, labeling, standardizing, using and disposing of laboratory reagents, indicator solutions and volumetric solutions.

2. Scope

This example SOP applies to QC laboratory personnel handling chemicals and solutions used in testing. It does not replace supplier instructions, safety data sheets (SDS), applicable pharmacopoeial procedures, approved analytical methods, local EHS requirements or the site’s quality system.

Related procedures include SOP on receipt and issue control of laboratory chemicals, SOP for handling laboratory reagents, SOP on cleaning laboratory glassware and SOP on disposal of chemical containers and solvent bottles.

3. Responsibilities

• Laboratory management: assigns trained personnel, defines responsibilities and ensures that suitable procedures, facilities and records are available.
• Preparer: checks source material and procedure, prepares and labels solutions, records calculations and preparation details, and reports discrepancies.
• Reviewer: independently checks records, calculations and standardization results where required by the approved method and risk assessment.
• QA or designated approver: approves controlled procedures, documented validity criteria and relevant deviations or changes under the site’s quality system.
• Stores or chemical custodian: maintains inventory and suitable storage, monitors expiry/retest status and issues materials under controlled arrangements.

4. Procedure

4.1 Receipt and storage of chemicals

1. Purchase chemicals from approved suppliers under the site purchasing procedure. Review the identity, grade, lot, certificate of analysis and SDS as applicable to the intended use.
2. On receipt, inspect the container and seal. Reject or quarantine damaged, unlabelled, expired, compromised or otherwise questionable material until its status is assessed.
3. Store each chemical under the manufacturer’s or approved method’s conditions, with incompatibilities and hazards considered. Keep containers identified and closed when not in use. Use suitable secondary containment or transfer equipment where required by the risk assessment.
4. Label and segregate hazardous chemicals according to SDS and local EHS requirements. Make current safety information and emergency procedures available to users.

4.2 Preparation and labeling of reagent or indicator solutions

1. Use the approved preparation method, applicable pharmacopoeial or other published standard where available, and appropriate grade of starting materials and water. Confirm the material identity, lot, expiry or retest status, and required storage before use.
2. Prepare solutions using suitable, clean equipment and a documented method. Record solution name and identifier, starting-material names and lots, quantities, final volume or concentration, method or reference, date prepared, preparer and required reviewer.
3. Assign a unique identifier that links the solution to its preparation record. Maintain a controlled register or equivalent system to show status, location, preparation details and expiry or retest date.
4. Label the container with its identity, concentration where applicable, solution identifier, preparation date, preparer identification, storage conditions and justified expiry or retest date. Add any required hazard warnings.
5. Use a compatible, clean container that protects the solution from contamination or deterioration. When transferring a reagent from its original container, identify the receiving container and maintain traceability to the source lot.
6. Before use, confirm identity, status, storage conditions and suitable appearance. Visual inspection alone does not establish concentration or fitness for a quantitative test.

4.3 Preparation and standardization of volumetric solutions

1. Prepare the solution according to the applicable monograph or approved analytical method. Record the formula or calculation, reagents and lots, quantities, final volume, equipment, preparation date and preparer.
2. Standardize the solution using a suitable primary standard or other standard prescribed by the method. Record the standard identity and lot, traceability and assigned value, mass or volume used, titration readings, calculations, factor or concentration, date, preparer and reviewer.
3. Perform the number of determinations and apply the acceptance criteria stated in the applicable monograph or approved method. If no method-specific criteria are stated, the laboratory should define and justify them before use. Investigate inconsistent or out-of-criteria results; do not select or average results solely to obtain an acceptable value.
4. Label the solution with its name, concentration or molarity, identifier, preparation and standardization dates, preparer identification, factor where relevant, storage conditions, and justified expiry or retest date. Ensure its suitability at the time of use.
5. Record the assigned factor in a controlled register and on the analytical record as required by the method. Verify solution identity and status before use and record the lot or solution identifier in the test data.
6. Re-standardize or otherwise verify a solution when required by the applicable method, its documented stability and use, storage conditions, observed change, or a deviation. Retire it when expired, unsuitable or outside approved criteria; document disposal.
7. Prepare diluted solutions using a documented calculation and suitable technique. Determine whether the method requires verification or re-standardization before use, and record the rationale and result.

4.4 Safety and waste

1. Review SDS and the laboratory’s task-specific risk assessment before handling chemicals. Use the PPE, engineering controls and handling procedures specified for the chemical and task.
2. Follow approved procedures for corrosive, volatile, toxic, flammable, oxidizing or otherwise hazardous materials. Use a fume hood or other containment when the SDS or risk assessment requires it. Never pipette by mouth.
3. Keep incompatible materials separated and containers appropriately closed and labeled. Follow the local spill and exposure response procedure; report incidents promptly.
4. Collect and dispose of chemical waste and empty containers under the site’s approved waste procedure and applicable local requirements. Do not pour chemicals to drain unless an approved procedure specifically permits it.

4.5 Deviations and document control

Record preparation errors, failed standardizations, unsuitable appearance, storage excursions, spills or other discrepancies under the site’s deviation procedure. Assess the impact on solutions and tests performed since the last acceptable check. Make changes to methods, validity periods or acceptance criteria through document and change control.

5. Source-template criteria for Admin verification

The following example in-house criteria appeared in the imported article. They are not universal regulatory requirements and are retained for Admin review only. WHO TRS 957 Annex 1 states that expiry or retest dates should be justified and that the laboratory should ensure volumetric solutions are suitable at the time of use.

• The source assigns reagent and indicator solutions a validity of 3 months unless otherwise specified, and volumetric solutions a validity of 1 month unless otherwise specified. Note: these validity periods are an example in-house criterion, not a pharmacopoeial requirement. Each solution’s expiry or retest period must be justified by stability data, storage conditions, container and intended use, and by any method-specific requirement in the applicable monograph or site procedure.
• The source says volumetric solutions are prepared once in a month or whenever required, standardization is performed in triplicate, and the molarity is determined with a precision of 0.5%. It also says repeat when triplicate factors differ by more than 0.5%.
• The source says to strengthen or dilute a solution and re-standardize when its factor is outside ±10% of theoretical value.
• The source says autotitrator standardization is performed before use and the resulting factor is valid for that day only.
• The source recommends glass-stoppered bottles for reagent and volumetric solutions and instructs visual appearance checks before each use.
• The source includes a fixed solution numbering format, annual preparation counts, company-specific GTP identifiers, and annexures for labels, registers and preparation records.
• The source instructs use of protective goggles and acid/alkali-resistant gloves for corrosives, a fume hood for corrosive liquids and dispensers for strong acids or alkalis. Note: this is an example of typical controls only. The actual PPE and engineering controls must be set per task and chemical from the current Safety Data Sheet and the site EHS risk assessment; one generic control does not suit every chemical or procedure.

6. Abbreviations

• EHS: Environment, Health and Safety
• GTP: General Test Procedure
• QC: Quality Control
• QA: Quality Assurance
• SDS: Safety Data Sheet
• VS: Volumetric solution

References

• World Health Organization (WHO), WHO good practices for pharmaceutical quality control laboratories, WHO Technical Report Series No. 957, Annex 1, 2010. See section 10 for reagent preparation, records, labeling, suitability, storage and retest dates; see section 21 for general safety guidance. Official WHO document