Preparation of Buffer Distilled Water at pH 7.2

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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

preparation of buffer distilled water ph 7.2

  1. Measure Distilled Water: Measure 1 L of distilled or deionized water into a flask or beaker.

  2. 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.

  3. Mix and Dissolve: Mix the solution by gently swirling the flask or beaker until the tablet is completely dissolved.

  4. 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.

  5. 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.

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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

  1. 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
  2. Neogen. (n.d.). Phosphate Buffer, pH 7.2, Product Information. Retrieved from https://www.neogen.com/globalassets/pim/assets/original/10000/7380_pi.pdf
  3. 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
  4. 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
  5. 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