Precision in volumetric transfer is a foundational requirement in most laboratory operations, particularly those involving solution preparation, calibration, and quantitative analysis. Among various liquid handling tools, the volumetric pipette remains one of the most trusted and accurate devices for single-volume measurements. This post outlines its functional uses, types, and structural variations, specifically referencing Class A and Class B pipettes, calibration specifications, and amber glass applications.
For laboratories handling scientific glassware, selecting the right pipette is not only about accuracy; it’s about traceability, compatibility with protocols, and reliability under repeated use.
Role of Volumetric Pipettes in Quantitative Analysis
Volumetric pipettes are calibrated to deliver a fixed and accurate volume of liquid at a defined temperature (usually 20 °C or 27 °C, depending on environmental norms). Unlike graduated pipettes, which can be used for variable volume transfer, volumetric pipettes are designed for single, accurate delivery, an essential requirement in titration, preparation of standard solutions, and analytical testing.
Typical use cases include;
- Pharmaceutical formulations: Standardisation of reference solutions
- Quality control labs: Routine quantitative assays
- Research facilities: Preparation of reagents for spectroscopy or enzyme assays
- Environmental testing labs: Trace sample dilution for GC or HPLC analysis
Where repeatability and compliance are non-negotiable, volumetric pipettes are often preferred over micropipettes, especially when working with aqueous samples or standard solvents.
Glass Type and Structure: Amber vs Clear
Volumetric pipettes are manufactured using borosilicate glass, offering high thermal resistance and chemical stability. For light-sensitive compounds, amber glass variants are used, not to be confused with amber coating, which may deteriorate over time and compromise sample protection.
| Glass Type | Use Case | Example Models |
| Clear Glass | General reagents, acids, buffers | 2040, 7100 |
| Amber Glass | Light-sensitive compounds (e.g. silver nitrate) | 7106 |
Note: Companies like Borosil Scientific manufacture volumetric pipettes using amber glass, not coating.
Comparison of Class A and Class B Volumetric Pipettes
The choice between Class A and Class B depends on the acceptable error margin and the regulatory requirements of the test method.
| Specification | Class A | Class B |
| Accuracy | High accuracy, tight tolerance | Standard tolerance |
| Certification | Individual Calibration Certificate | No individual certificate |
| Best Used In | Audit-ready labs, calibration work | Academic labs, routine procedures |
| Relevant Standards | ISO, ASTM | ASTM |
| Available Models | 2040, 7100, 7101, 7106 | 7102, 7103 |
Volumetric Pipette Portfolio: Models and Specifications
Many premium providers offer a wide range of volumetric pipettes manufactured to ISO and ASTM standards, suitable for various scientific workflows.
| Model No. | Accuracy Class | Standard | Colour | Certification | Remarks |
| 2040 | Class A | ISO | Clear | Individual Calibration Certificate | NABL Certified |
| 7100 | Class A | ISO | Clear | Individual Calibration Certificate | Ideal for pharmaceutical QC labs |
| 7101 | Class A | ASTM | Clear | Individual Calibration Certificate | Common in GLP-compliant environments |
| 7106 | Class A | ASTM | Amber | Individual Calibration Certificate | Light-sensitive solution preparation |
| 7102 | Class B | ASTM | Clear | Not individually certified | Good for routine tests |
| 7103 | Class B | ASTM | Clear | Not individually certified | Used in educational setups |
All models are designed to deliver a single marked volume and are calibrated to contain or deliver (TD) as per the designated standard.
Volume Range and Calibration Standards
Pipettes are available in a wide range of capacities to suit varied laboratory applications. Companies like Borosil Scientific offer volume capacities starting from 1 ml up to 100 ml. The choice of volume depends on the type of experiment and the sensitivity of the test to volume.
| Volume Range | Best For |
| 1- 5 ml | Titrations, enzyme assays, trace sample prep |
| 10- 25 ml | Standard solution preparation |
| 50- 100 ml | Buffer dilution, stock solution dispensing |
All Class A models from Borosil Scientific comply with calibration requirements traceable to national standards and include individual certificates per item. Calibration is typically carried out at 20 °C, following ISO 648 and ASTM E969, depending on the model.
Considerations in Analytical and HPLC Sample Preparation
In procedures involving HPLC vials or analytical vials, volumetric accuracy plays a significant role in sample integrity. Inconsistent sample concentration due to incorrect pipetting can affect baseline stability, peak area, and overall reproducibility.
For HPLC applications:
- Use Class A pipettes with traceable calibration
- Always rinse the pipette with the sample before use (pre-conditioning)
- Choose amber pipettes for light-sensitive mobile phases or analytes
- Match pipette size closely to the required volume; don’t use oversized pipettes for small transfers
Note on Certification: HPLC vials are ISO 15378 certified. No individual certificates are provided- only COA (Certificate of Analysis) is issued per lot.
Handling, Maintenance, and Best Practice Guidelines
Improper use or storage can degrade the accuracy of volumetric pipettes. For laboratory environments requiring reliable results (particularly in GMP/GLP-compliant workflows), the following precautions are essential:
- Rinse after each use: Especially when working with organic solvents or protein-based reagents.
- Avoid air bubbles: Ensure vertical alignment and slow delivery to prevent volume deviation.
- Inspect regularly: Look for chips, residue buildup, or illegible calibration marks.
- Storage: Store pipettes in an upright stand. Avoid horizontal placement or crowding.
Calibration should be verified annually or more frequently, depending on use frequency. Pipettes involved in regulatory documentation or trace testing should be subjected to routine verification using gravimetric or photometric methods.
Conclusion:
Selecting the correct volumetric pipette is a technical decision based on multiple factors, including accuracy class, volume capacity, certification needs, and chemical compatibility. Laboratories handling scientific glassware for high-precision analysis, reagent standardisation, or pharmaceutical formulation require equipment that aligns with standardised testing methods.
Class A pipettes such as 2040, 7100, and 7101 are suitable for laboratories where compliance and traceability are critical. Amber variants like 7106 provide added protection for photolabile samples. For academic or non-critical operations, Class B models like 7102 and 7103 offer cost-effective reliability.