May 30, 2024

Preparation of buffer solution and measurement of pH

Preparation of buffer solution and measurement of pH

Citation: Chaudhari, M. (2022). Preparation of buffer solution. Pharmacy Infoline. https://doi.org/10.5281/zenodo.10826597

DOI

buffer solution ph measurement can be performed as

Aim:

To prepare carbonate buffer and its measurement of PH by using PH meter

Material/Requirement:

  • Sodium bicarbonate
  • Sodium carbonate
  • Distilled water
  • 100ml volumetric flask
  • Beaker
  • Stirrer

Procedure:

To 93 ml of 0.1M sodium bicarbonate in volumetric flask and 0.1M sodium bicarbonate was added to make up the volume up to 100ml. The PH was measured by the pH meter

Preparation of 0.1M sodium bicarbonate

8.4gm of sodium bicarbonate in 1000ml of water

Preparation of 0.1M sodium carbonate

28.6 g of sodium carbonate in 1000ml of water.

Report:

Carbonate buffer was prepared and the pH was found to be ——–


Preparation of Buffer Solutions: A Standard Procedural Guide

Buffer solutions are fundamental components in various scientific disciplines, particularly biochemistry, molecular biology, and analytical chemistry. They maintain a stable pH environment, crucial for many biological processes and chemical reactions. This article outlines the standard procedure for preparing buffer solutions.

Materials:

  • Analytical balance
  • Graduated cylinders
  • Volumetric flasks
  • Pipettes
  • Magnetic stirrer with stir bar
  • pH meter (calibrated)
  • Deionized (DI) water
  • Acid (weak)
  • Base (conjugate of the weak acid) or vice versa

Procedure:

  1. Selection of Buffer System: Choose a suitable buffer system based on the desired pH range. Common buffer systems include:
    • Acetate buffer (pH 3.6 – 5.5): Acetic acid (CH3COOH) and sodium acetate (CH3COONa)
    • Phosphate buffer (pH 5.8 – 8.0): Phosphoric acid (H3PO4) and sodium phosphate (Na2HPO4 or Na3PO4)
    • Tris-HCl buffer (pH 7.0 – 9.2): Tris(hydroxymethyl)aminomethane (Tris) and hydrochloric acid (HCl)
  2. Preparation of Stock Solutions: Prepare 0.1 M solutions of the chosen weak acid and its conjugate base (or vice versa) in separate volumetric flasks using DI water. Accurately weigh the required amount of the acid/base using the analytical balance and dissolve it in a portion of DI water. Dilute to the final volume with DI water and mix thoroughly using a magnetic stirrer.
  3. Calculation of Buffer Ratio: Utilize the Henderson-Hasselbalch equation to determine the appropriate ratio of acid to conjugate base for achieving the desired pH:

pH = pKa + log ([Base] / [Acid])

where:

  • pH is the desired final pH
  • pKa is the acid dissociation constant of the weak acid
  • [Base] is the concentration of the conjugate base
  • [Acid] is the concentration of the weak acid

Resources providing pre-calculated ratios for various buffer systems at specific pH values are available online or in reference books.

  1. Buffer Preparation: Using pre-calculated ratios or the Henderson-Hasselbalch equation, determine the volume of each stock solution needed. Pipette the calculated volumes of the acid and base stock solutions into a clean volumetric flask. Add a small amount (around 60%) of DI water and mix thoroughly.
  2. pH Measurement and Adjustment: Measure the pH of the prepared solution using a calibrated pH meter. If the pH deviates from the desired value, carefully add small aliquots of the more concentrated acid or base solution (depending on whether the measured pH is higher or lower than desired) while continuously monitoring the pH with stirring.

6. Dilution and Storage: Once the desired pH is achieved, dilute the solution to the final volume with DI water and mix thoroughly. Store the prepared buffer solution in a clean, labeled bottle at the appropriate temperature (usually 4°C).

Safety Precautions:

  • Wear personal protective equipment (PPE) such as gloves, safety glasses, and lab coat while handling chemicals.
  • Handle concentrated acids and bases with caution.
  • Dispose of waste solutions according to recommended protocols.

Additional Notes:

  • This is a general guideline, and specific protocols may vary depending on the chosen buffer system and application.
  • For high-precision applications, consider using commercially prepared buffer solutions.
  • Buffer capacity refers to the ability of a buffer to resist changes in pH upon addition of small amounts of acid or base. You can adjust the total concentration of the buffer solution (acid + conjugate base) to achieve the desired buffer capacity.

By following these steps and considering the additional notes, you can effectively prepare buffer solutions for your scientific experiments.

Suggested Reading:


First Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise

F Y B Pharm Sem-IF Y B Pharm Sem-II
BP101T Human Anatomy and Physiology I TheoryBP201T Human Anatomy and Physiology II – Theory
BP102T Pharmaceutical Analysis I TheoryBP202T Pharmaceutical Organic Chemistry I Theory
BP103T Pharmaceutics I TheoryBP203T Biochemistry – Theory
BP104T Pharmaceutical Inorganic Chemistry TheoryBP204T Pathophysiology – Theory
BP105T Communication skills TheoryBP205T Computer Applications in Pharmacy Theory
BP106RBT Remedial BiologyBP206T Environmental sciences – Theory
BP106RMT Remedial Mathematics TheoryBP207P Human Anatomy and Physiology II Practical
BP107P Human Anatomy and Physiology PracticalBP208P Pharmaceutical Organic Chemistry I Practical
BP108P Pharmaceutical Analysis I PracticalBP209P Biochemistry Practical
BP109P Pharmaceutics I PracticalBP210P Computer Applications in Pharmacy Practical
BP110P Pharmaceutical Inorganic Chemistry Practical
BP111P Communication skills Practical
BP112RBP Remedial Biology Practical