Standard Operating Procedure (SOP)

Here is a complete Standard Operating Procedure (SOP) for the Cleaning of Glassware Used in Chemical Testing:

1. Purpose

To describe a standardized procedure for the cleaning of glassware used in chemical testing to ensure accuracy, reliability, and reproducibility of analytical results by avoiding cross-contamination and residue interference.

2. Scope

This SOP applies to all laboratory personnel involved in chemical testing and responsible for cleaning glassware in the Quality Control Laboratory.

3. Responsibilities

• Laboratory Personnel shall:

  • Clean glassware as per this SOP immediately after use.

  • Ensure all residues are removed before reuse.

• Lab Supervisor shall:

  • Ensure compliance and proper training of lab staff in cleaning procedures.

4. Materials and Equipment Required

• Laboratory detergent (e.g., Liquinox or equivalent)

• Tap water

• Deionized (DI)/distilled water

• Acetone or ethanol (for specific rinsing)

• Cleaning brushes of appropriate size

• Cleaning gloves and lab coat

• Fume hood (if using volatile solvents)

• Drying oven or clean air-drying rack

• Waste disposal container

5. Procedure

5.1 General Cleaning Steps for Most Glassware

1. Wear appropriate PPE (gloves, goggles, lab coat).

2. Immediately after use, rinse the glassware with tap water to remove most residues.

3. Add a small amount of laboratory detergent and scrub with an appropriate brush to remove all residues.

4. Rinse thoroughly with tap water until all soap is removed.

5. Rinse with deionized/distilled water at least 3 times to remove any ions or contaminants.

6. If required, perform a final rinse with acetone or ethanol (especially for organic residue removal).

7. Place cleaned glassware in a drying oven at 60–80°C or let it air-dry on a dust-free rack.

5.2 For Volumetric Glassware (e.g., pipettes, burettes, flasks)

1. Rinse with tap water immediately after use.

2. Clean with detergent and brush carefully—avoid scratching calibrated markings.

3. Rinse thoroughly with tap water and then with deionized/distilled water at least 3 times.

4. Allow to air-dry inverted on a clean rack or dry with hot air without direct contact.

5.3 For Glassware Containing Organic Residues

1. Rinse with suitable organic solvents (e.g., acetone, ethanol, or methanol) under a fume hood.

2. Proceed with standard detergent cleaning.

3. Rinse with deionized water thoroughly.

4. Dry as described above.

5.4 For Glassware with Stubborn or Inorganic Residues

1. Soak in 1–2% nitric acid or chromic acid solution if permitted (use with caution).

2. Rinse thoroughly with tap water followed by deionized water.

3. Follow institutional disposal procedures for acid waste.

6. Cleaning Frequency

• Immediately after use for routine items.

• Before use, if glassware has been stored for a long time.

7. Waste Disposal

• Dispose of used solvents and acids according to local regulations and hazardous waste disposal SOP.

• Never pour solvents or acids directly down the sink.

8. Documentation

• Maintain a cleaning log if required by regulatory or internal QA standards, especially for specialized or critical glassware.

• Log should include date, glassware type, and initials of the person responsible.

9. Precautions

• Avoid using scratched or damaged glassware.

• Do not mix incompatible solvents.

• Do not use glassware while wet for moisture-sensitive analyses.

10. References

• Good Laboratory Practice (GLP) Guidelines

• Laboratory Glassware Manufacturer’s Instructions

• ISO/IEC 17025 Guidelines

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