A burette is a precision laboratory instrument used to deliver controlled and accurately measured volumes of liquid, particularly during titration. It is widely used in chemistry, pharmaceutical, research, educational, and analytical laboratories.
Its graduated tube and controlled-flow stopcock allow liquid to be dispensed gradually, making it useful for determining the endpoint of chemical reactions.
What Is a Burette?
A burette is a graduated volumetric laboratory instrument designed to dispense a known volume of liquid with controlled flow. It is primarily used in titration, where one solution is gradually added to another until the desired chemical endpoint is reached.
A typical burette consists of:
- A long graduated glass tube
- A stopcock or control valve
- A burette tip
- Graduated volume markings
The existing LABIX guide describes the burette as measuring the liquid delivered rather than the liquid contained.
Burette Diagram and Parts
Understanding the burette diagram makes it easier to identify the different components and understand how the instrument operates.
1. Graduated Glass Tube
The long vertical tube contains the liquid being dispensed. Its graduation marks allow the user to determine the volume delivered during an experiment.
2. Stopcock
The stopcock is positioned near the bottom of the burette and controls the flow of liquid.
Common stopcock types include:
- Glass stopcock
- PTFE stopcock
A PTFE stopcock can be useful for applications involving chemicals where chemical resistance is important.
3. Burette Tip
The narrow tip at the bottom allows liquid to be delivered in a controlled stream or dropwise manner.
4. Graduation Scale
The graduated scale provides volume readings, generally in millilitres (mL), allowing the user to calculate the amount of solution delivered.
Burette Working Principle
The working principle of a burette is based on controlled delivery and volume measurement.
During a typical titration:
- The burette is cleaned and prepared.
- It is rinsed with the solution that will be used.
- The burette is filled with the solution.
- The initial volume reading is recorded.
- The stopcock is opened to deliver the solution gradually.
- The endpoint of the titration is identified.
- The final volume reading is recorded.
- The volume delivered is calculated using:
Volume delivered = Final reading − Initial reading
The current LABIX article uses this same basic calculation and describes controlled dropwise delivery as the operating principle.
Uses of a Burette
The main use of a burette is accurate liquid delivery during titration. It can be used in several types of analytical procedures.
Acid-Base Titration
Burettes are commonly used to determine the concentration of an acidic or basic solution through controlled addition of a standard solution.
Redox Titration
They can be used for oxidation-reduction titrations in analytical chemistry.
Complexometric Titration
Burettes are also used when determining concentrations of certain metal ions through complexometric titration.
Educational Laboratories
Burettes are widely used in school, college, and university chemistry laboratories for practical experiments involving titration and quantitative analysis.
Pharmaceutical and Research Laboratories
Burettes can support solution standardization, chemical analysis, quality-control procedures, and research applications.
The existing LABIX guide identifies titration, analytical chemistry, quality-control testing, chemical studies, pharmaceutical analysis, and research as key application areas.
Types of Burette
Different types of burettes are available depending on the required volume, dispensing method, and application.
1. Glass Burette
Glass burettes are commonly used in educational and general laboratory applications.
Features include:
- Graduated glass tube
- Controlled liquid delivery
- Suitable for titration
- Available with different stopcock arrangements
2. Digital Burette
A digital burette provides a digital volume display and controlled dispensing.
Common features include:
- Digital volume indication
- Controlled dispensing
- Reduced dependence on manual reading
- Suitability for applications requiring controlled liquid delivery
3. Automatic Burette
Automatic burettes are designed for controlled or automated dispensing and may be used in laboratories requiring more advanced liquid-handling capabilities.
4. Micro Burette
Micro burettes are designed for applications involving relatively small liquid volumes and can be useful in research and micro-scale analytical procedures.
Burette Stand
A burette stand supports the burette in a vertical position during titration.
Keeping the burette stable helps the user read the graduation scale consistently and operate the stopcock safely.
A typical setup may include:
- Base
- Supporting rod
- Burette clamp
Why Is a Burette Stand Important?
A properly positioned burette stand helps:
- Keep the burette vertical
- Reduce movement during titration
- Support consistent readings
- Improve laboratory safety
- Make stopcock operation easier
The current LABIX guide describes cast-iron, wooden, and adjustable metal stand arrangements.
How to Use a Burette
Correct preparation and operation are important for reliable titration results.
Step 1: Clean the Burette
Clean the burette appropriately and rinse it with distilled water.
Step 2: Rinse With the Working Solution
Rinse the burette with a small quantity of the solution that will be used for titration.
Step 3: Fill the Burette
Fill the burette with the required solution and ensure that the dispensing tip is properly filled.
Step 4: Remove Air Bubbles
Check the tip and remove any trapped air bubbles before taking the initial reading.
Step 5: Record the Initial Reading
Record the starting volume carefully.
Step 6: Perform the Titration
Open the stopcock gradually and control the liquid flow. Near the endpoint, slower dropwise addition may be required.
Step 7: Record the Final Reading
After reaching the endpoint, record the final burette reading.
Step 8: Calculate the Volume Delivered
Subtract the initial reading from the final reading.
Common Burette Reading Errors
Several factors can affect the accuracy of a burette reading.
Air Bubbles
Air trapped in the tip can affect the volume delivered.
Parallax Error
Reading the scale from an incorrect viewing angle can introduce measurement errors.
Incorrect Initial Reading
An incorrectly recorded starting value directly affects the calculated volume.
Excessively Fast Dispensing
Releasing solution too quickly can make endpoint detection more difficult during titration.
The existing LABIX guide specifically identifies air bubbles, parallax error, incorrect zero setting, and rapid liquid release as common mistakes.
Burette Price in India
The price of a burette varies according to its type, material, capacity, accuracy requirements, manufacturer, and features.
The current LABIX page gives the following approximate ranges:
| Burette Type | Approximate Price Range |
|---|---|
| Glass Burette | ₹400 – ₹1,500 |
| Digital Burette | ₹15,000 – ₹50,000 |
| Automatic Burette | ₹30,000 – ₹1,00,000 |
These figures are presented on the existing LABIX article as approximate ranges and may change depending on product specifications, brand, accuracy class, and market conditions.
Factors Affecting Burette Price
When comparing burette prices, consider:
- Material
- Capacity
- Accuracy class
- Calibration requirements
- Stopcock type
- Manual or digital operation
- Manufacturer
- Product certification
- Application requirements
A laboratory should select a burette based on the required specifications rather than price alone.
Burette Cleaning and Maintenance
Proper cleaning and handling help maintain the condition and performance of laboratory glassware.
Cleaning
After use:
- Rinse the burette appropriately.
- Remove chemical residues.
- Avoid leaving incompatible solutions inside the burette.
- Follow the manufacturer’s cleaning recommendations.
Storage
For safe storage:
- Handle glass burettes carefully.
- Protect them from physical impact.
- Keep them clean and free from chemical residue.
- Store them appropriately according to laboratory procedures.
The existing LABIX guide recommends rinsing with distilled water, avoiding detergent residue, and handling/storing the burette carefully.
Burette vs Pipette
Although both are volumetric laboratory instruments, their typical functions differ.
| Feature | Burette | Pipette |
|---|---|---|
| Primary purpose | Controlled dispensing | Transfer of measured volume |
| Common application | Titration | Sample/solution transfer |
| Liquid delivery | Controlled and variable | Usually a defined volume |
| Flow control | Stopcock | Depends on pipette type |
The appropriate instrument depends on the laboratory procedure and required measurement.
Advantages of Using a Burette
A burette is useful for laboratory applications requiring controlled liquid delivery because it provides:
- Graduated volume measurement
- Controlled dispensing
- Dropwise liquid delivery
- Suitability for titration
- Repeatable analytical procedures
- Compatibility with many chemistry laboratory applications
Applications of Burettes
Burettes are used in:
- Analytical chemistry
- Pharmaceutical laboratories
- Research laboratories
- Educational institutions
- Quality-control laboratories
- Chemical testing
- Standardization procedures
- Titration experiments
How to Choose a Burette
Before purchasing a burette, consider the following:
- Application – Determine whether it will be used for routine titration, research, or specialized analysis.
- Capacity – Select an appropriate volume range.
- Accuracy – Consider the required accuracy class and calibration requirements.
- Material – Choose suitable glass or other compatible materials.
- Stopcock – Consider glass or PTFE depending on chemical compatibility.
- Ease of Use – Digital or automatic options may be suitable for particular workflows.
- Calibration and Certification – Check documentation when traceable measurement is required.
- Manufacturer Support – Consider product availability, technical support, and replacement components.
Conclusion
A burette is an important laboratory instrument for controlled and measured liquid delivery, particularly in titration and analytical chemistry. Understanding its parts, diagram, working principle, types, uses, operating procedure, and maintenance can help students and laboratory professionals use it correctly.
The right burette should be selected according to the application, required capacity, accuracy, material compatibility, calibration requirements, and laboratory procedures.
For reliable results, always follow the manufacturer’s instructions and applicable laboratory standards when using and maintaining a burette.