Preparing buffer distilled water at pH 7.2 is a crucial step in various applications, including the preparation of Giemsa stain working solutions for staining malaria blood films. This comprehensive guide outlines the step-by-step procedure for creating buffered water from buffer tablets to achieve a pH of 7.2.
Materials and Equipment
To prepare buffer distilled water at pH 7.2, you will need the following materials and equipment:
Item | Quantity |
---|---|
Commercial phosphate buffer tablets for 1 L of water (pH 7.2) | 1 |
Commercial distilled or deionized bottled water | 1 L |
Graduated cylinder | 1 L capacity |
Conical flask or beaker | 1 L capacity |
Screw-capped glass bottle | 1 L or 500 mL capacity, clean and dry |
Small tongs or tweezers | 1 |
Procedure
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Measure Distilled Water: Measure 1 L of distilled or deionized water into a flask or beaker.
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Add Buffer Tablet: Using small tongs or a tweezer, place one phosphate buffer tablet into the flask or beaker. Be careful not to touch the tablet with your hand.
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Mix and Dissolve: Mix the solution by gently swirling the flask or beaker until the tablet is completely dissolved.
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Label and Document: Label the bottle of buffered water with the date prepared, expiry date, and the name of the person who prepared it. Document the procedure in the quality control log-book.
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Use and Storage: Use the water buffered to pH 7.2 to prepare the Giemsa working solution. Store the prepared buffered water in a cool place away from direct sunlight. Use a dark bottle or a clear glass bottle wrapped in brown paper to prevent bacterial, fungal, and algal growth. Check continuously for contamination and do not keep the buffer solution for more than 7 days to avoid a change in pH and to prevent contamination.
Important Notes
- Buffer tablets must be kept in an airtight container, away from sunlight and damp.
- Always check the expiration date of the buffer tablets before use.
- Follow the manufacturer’s guidance for use and storage of buffer tablets.
- Use only the amount of water specified by the manufacturer. Failure to do so will result in poor staining results.
- If facilities are available, check the pH of buffered water routinely before use.
References
- World Health Organization. (2016). Preparation of water buffered to pH 7.2 with buffer tablets. Retrieved from https://www.who.int/publications/i/item/HTM-GMP-MM-SOP-03b
- Neogen. (n.d.). Phosphate Buffer, pH 7.2, Product Information. Retrieved from https://www.neogen.com/globalassets/pim/assets/original/10000/7380_pi.pdf
- ResearchGate. (2013). How to prepare a 0.2 M phosphate buffer (Na2HPO4-NaH2PO4), pH 6.4. Retrieved from https://www.researchgate.net/post/How-to-prepare-a-0-2-M-phosphate-buffer-Na2HPO4-NaH2PO4-pH-64
- U.S. Food and Drug Administration. (2020). BAM R11: Butterfield’s Phosphate-Buffered Dilution Water. Retrieved from https://www.fda.gov/food/laboratory-methods-food/bam-r11-butterfields-phosphate-buffered-dilution-water
- World Health Organization. (2016). Preparation of water buffered to pH 7.2 with buffer tablets. Retrieved from https://www.who.int/docs/default-source/wpro—documents/toolkit/malaria-sop/gmp-sop-03b.pdf?sfvrsn=1ca3146e_2