How to Make 25 Percent Glucose Solution

December 20, 2025 •

3 min read

According to Perth Children's Hospital guidelines, a 25% glucose solution is created by mixing 25 grams of glucose powder with 100 milliliters of water. This concentrated solution requires precise measurement to ensure the desired concentration for its intended use.

Quick Summary

This guide provides instructions for preparing a 25% glucose solution using precise calculations and techniques for lab or general use. Proper weighing, dilution, and storage procedures are explained to ensure accuracy. It also covers important considerations and safety measures.

Key Points

Calculation: A 25% glucose solution requires 25 grams of glucose powder for every 100 milliliters of total solution volume.
Method Selection: The solution can be made from raw glucose powder or by diluting a more concentrated stock solution, such as a 1:1 dilution of 50% dextrose.
Equipment: A lab balance, volumetric flask, and appropriate water are essential for accurate preparation.
Safety: Always use appropriate Personal Protective Equipment (PPE) when handling chemicals.
Dilution Example: To create 50 mL of 25% glucose, combine 25 mL of 50% dextrose stock solution with 25 mL of water.
Storage: Store the solution in a sealed, clearly labeled container in a cool, dark place.

Understanding the Fundamentals of a 25% Glucose Solution

Before embarking on the preparation, it's essential to understand what a 25% glucose solution means. In chemistry, this percentage is typically interpreted as a weight-per-volume concentration (w/v), meaning 25 grams of glucose (the solute) are dissolved in a total volume of 100 milliliters (the solvent and solute combined). This concentrated form is often referred to as dextrose, a term used interchangeably with D-glucose in various contexts. The specific concentration is critical for various applications where precise measurement is necessary. The purity of the glucose powder and the nature of the water used are important for achieving the correct concentration and avoiding unwanted contaminants.

Preparing the Solution for Laboratory Use

For general lab purposes, preparing a 25% glucose solution requires precision. The basic formula involves weighing the correct amount of glucose and dissolving it in a smaller volume of distilled water before bringing the total volume up to the desired mark. A common method involves using a volumetric flask to ensure accuracy.

Here is a step-by-step guide for preparing 100 mL of a 25% glucose solution for laboratory experiments:

Gather Materials: You will need anhydrous glucose powder, distilled or deionized water, a laboratory balance, a beaker, a 100 mL volumetric flask, and a stir rod.
Calculate the Mass: As per the 25% w/v definition, you will need 25 grams of glucose for every 100 mL of solution.
Weigh Accurately: Using the laboratory balance, measure out exactly 25 grams of glucose powder. Ensure the balance is tared (zeroed) before adding the powder.
Initial Dissolving: Pour about 50-60 mL of distilled water into a beaker. Add the weighed glucose powder to the water and stir thoroughly until it is completely dissolved. Glucose is highly soluble.
Final Volume Adjustment: Carefully transfer the dissolved glucose solution into the 100 mL volumetric flask. Use a wash bottle with distilled water to rinse any remaining residue from the beaker and stir rod into the flask. Add more distilled water to the flask until the bottom of the meniscus is precisely at the 100 mL mark. It is crucial to add the final drops slowly to avoid overshooting the mark.
Label and Store: Affix a label detailing the solution's concentration (25% glucose), the date of preparation, and your initials. Store the solution in a sealed container in a cool, dark place.

Comparison of Preparation Methods


Feature	Direct Mass-to-Volume Method (from powder)	Dilution Method (from 50% stock)
Accuracy	High accuracy if using a precise volumetric flask.	Depends on the accuracy of the stock solution and pipetting.
Speed	Relatively fast if starting with powder.	Often faster for preparing smaller volumes.
Equipment	Requires an analytical balance, beaker, volumetric flask.	Requires a pipette and a volumetric flask.
Key Benefit	Allows for preparation from raw material, ensuring exact concentration from scratch.	Can be efficient when starting from a concentrated stock solution.
Application	Suitable for preparing a fresh batch or for labs without concentrated stock.	More efficient for preparing specific volumes by reducing preparation steps.

Preparing via Dilution from a 50% Dextrose Stock

In settings that stock higher concentrations, preparing a 25% solution can be done by simple dilution. A common method involves a 1:1 dilution of a 50% dextrose stock solution with water.

The Formula: The dilution formula C1V1 = C2V2 is used, where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume. For a 1:1 dilution, this is simplified.
Example: To create 50 mL of 25% glucose, you would take 25 mL of 50% dextrose solution and mix it with 25 mL of water.
Procedure: Using appropriate measuring tools, withdraw the required volume of 50% dextrose. Add this to an equal volume of water in a suitable container. Mix well.

Safety Precautions and Considerations

Proper technique and safety are crucial when preparing any chemical solution. Use Personal Protective Equipment (PPE) such as gloves and safety goggles. Ensure all equipment is clean and, if necessary, sterilized. Consult the product's Safety Data Sheet (SDS) for specific handling and disposal instructions, though glucose is generally not considered a hazardous substance.

Conclusion

Creating a 25% glucose solution is a straightforward process when the fundamental principles of concentration and measurement are followed. Whether starting with glucose powder or diluting a pre-existing stock solution, accuracy is key to ensuring the solution's effectiveness and reliability for various scientific applications. By adhering to proper laboratory procedures, individuals can confidently prepare this solution. For those needing guidance on specific laboratory techniques, resources like the Chemistry LibreTexts can be helpful.

Frequently Asked Questions

A 25% glucose solution, typically interpreted as weight-per-volume (w/v), means that 25 grams of glucose solute are present in every 100 milliliters of the final solution.

For practical and biochemical purposes, dextrose is identical to D-glucose. The terms are often used interchangeably, though dextrose specifically refers to the naturally occurring D-isomer of glucose.

To make a 25% solution from a 50% stock, you perform a 1:1 dilution. For example, combine 25 mL of 50% dextrose with 25 mL of water to get 50 mL of 25% dextrose.

For standard laboratory use, distilled or deionized water is sufficient.

Store the solution in a sealed, clearly labeled container in a cool, dark place.

25% glucose solutions are used in various laboratory experiments and preparations where a specific concentration is required.

Yes, wear gloves and eye protection. Consult the product's Safety Data Sheet (SDS) for any specific hazards or disposal requirements.

Use a laboratory-grade analytical balance for weighing the glucose powder. For the liquid volume, use a volumetric flask to ensure the final volume is precise, filling carefully to the calibration mark.