Pipette (Glass Pipettes) - Principle, Types, Handling, and Uses

Pipette (Glass Pipettes) is a laboratory instrument made up of a narrow glass tube that is used to measure and transfer a specific volume of liquid from one container to another. It works by creating a suction or partial vacuum above the liquid (using pipette bulb or mouth suction) so the liquid is drawn inside the tube and then the vacuum is released to dispense it.

Glass pipettes are mostly made of borosilicate glass or soda-lime glass, hence they show good transparency, thermal stability and chemical resistance for acids, bases and organic solvents. In glass pipettes, capillary action also helps in drawing the liquid up the narrow tube because the glass surface attracts the liquid. These pipettes are reusable and can be sterilized (autoclave), and they are mainly of two types i.e volumetric pipette (fixed accurate volume) and graduated pipette (variable volume measuring).

Features of Pipettes (Glass Pipettes)

Material composition- Glass pipettes are made from borosilicate glass, soda-lime glass, aluminosilicate or quartz, depending on lab use.
Chemical inertness- They have very good chemical resistance. Strong acids, strong bases and organic solvents (hexane, acetone) can be handled, which may damage plastic pipettes.
Thermal stability and sterility- Glass gives high thermal stability. It can be sterilized in autoclave for aseptic work in microbiology and cell culture, and used again.

High precision and accuracy- Glass pipettes are accurate and used for precise measurement. They are classified as Class A (high precision) and Class B (general use). Since glass is rigid, it is less affected by heat of hand, so measurement stays more accurate.
Reusability and sustainability- Glass pipettes are durable and reusable. It reduces plastic waste and supports green chemistry type laboratory practice.
Structural design- It has a suction tube and a delivery tube, and sometimes a bulb is present between them. Under ASTM E969, minimum wall thickness is maintained for stability, and the delivery tip is tapered gradually (about 1.5 to 3 cm).

Capillary action- Glass surface (silicon dioxide) is polar and forms hydrogen bonds with liquids like water. In narrow-bore pipette, liquid can rise by capillary action even without external vacuum, like in blood sample pipettes.
Permanent markings- Capacity line and graduation markings are made permanent by etching, firing stain or enamel, so it remains readable for long time.
Transparency- Glass is transparent, so the meniscus can be seen clearly for correct reading.

Fragility- Glass pipettes break easily compared to plastic. It needs careful handling and proper PPE during use.

Principle of Pipette (Glass Pipettes)

Principle of Pipette (Glass Pipettes) is based on creating a pressure difference inside the glass tube. In the first, air inside the pipette is removed by using a rubber bulb or suction device and a partial vacuum is formed. When the pipette tip is kept inside the liquid and the suction is released, the outside atmospheric pressure forces the liquid to move upward into the low pressure space. The liquid rises up to a level where inside pressure and the hydrostatic pressure (weight of the liquid column) balances the atmospheric pressure.

It is also based on capillary action in the narrow bore of the glass pipette. Glass surface attracts polar liquids by adhesion, so liquid wets the wall and climbs along the inner side. Cohesion between the liquid molecules keeps the column continuous and pulls more liquid upward. Finally the rise stops when the weight of the liquid column counteracts the upward pull, and the liquid can be held and then dispensed in required volume.

Parts of Pipette (Glass Pipettes)

Suction tube. It is the upper narrow part of the pipette. Rubber bulb or suction pump is attached here to draw the liquid upward.
Bulb. It is the widened middle part seen in volumetric pipette. It holds the major volume of liquid. In graduated pipette, this bulb part is not present and the tube is straight.
Delivery tube. It is the lower narrow part below the bulb. It connects the bulb portion to the tip portion.

Delivery tip. It is the bottom end of the pipette. It is gradually tapered with a smooth opening (ground or fire polished) from where the liquid comes out.
Capacity line or graduation marks. It is a permanent marking on the glass. In volumetric pipette it is a single sharp line showing the fixed volume. In graduated pipette it is a series of markings showing different volumes to hold or deliver.
Color coding bands. These are one or more coloured rings near the top part. It is used to identify the nominal capacity quickly.

Identification markings. These are printed details on the glass. It shows manufacturer name, nominal capacity, calibration temperature (usually 20°C), accuracy class (Class A or B), and TD (to deliver) or TC (to contain) marking.

Types of Pipette (Glass Pipettes)

Volumetric (Transfer) pipette. It is a glass pipette designed to deliver a single fixed volume. It has a central bulb with narrow stem. It is calibrated for high accuracy in measurement.
Graduated (Measuring) pipette. It is a straight bore glass tube with graduation marks along the length. It is used to measure and transfer variable volumes.

Mohr pipette. It is a type of graduated pipette. The graduation marks end before the tip. The liquid present in the tip is not included in the measured volume.
Serological pipette. It is also a graduated pipette. The graduation marks extend up to the tip. Many are blow out type, so final drop is expelled to deliver full volume.
Pasteur pipette. It is a simple ungraduated glass pipette with narrow taper end. It is used with rubber bulb to transfer small quantity liquid drop by drop without exact measurement.

Ostwald-Folin pipette. It is a special volumetric pipette with bulb near the delivery tip. It is used for viscous fluids like blood and serum for accurate transfer.
Van Slyke pipette. It is a graduated pipette used in medical and volumetric analysis work.
Hagedorn pipette and Folin-Wu pipette. These are constricted glass pipettes used in clinical diagnosis. It is used in blood sugar estimation and for handling protein free filtrates.

Bacteriological pipette. It is used in bacteriological work. It may contain a fibre filter to prevent contamination by liquid vapor or fluid entry.
Winkler-Dennis gas combustion pipette. It is a special apparatus type pipette used for controlled reaction of liquids with mild electric current and oxygen supply.
Glass micropipette. It is very fine glass tubing prepared by pulling method. It is used in micromanipulator work like microinjection and patch clamp applications.

Operating Procedure of Pipette (Glass Pipettes)

Preparation and conditioning

Inspect the glass pipette for any crack or chip before using. The outside of the pipette should be dry. In this step, pipette is conditioned by taking small amount of the same solution inside and rotating it in horizontal position to rinse inner wall. The rinse liquid is discarded into waste beaker and this is repeated 2 to 3 times.

Filling the pipette

Squeeze the rubber bulb first to remove air and then it is fitted on the top of the pipette. The pipette tip is dipped into the sample liquid. Now bulb pressure is released slowly and liquid is drawn up slightly above the required calibration mark. Remove the bulb and close the top opening immediately with index finger. Wipe the outer surface of the tip with lint free tissue to remove extra droplets.

Adjusting the volume

Hold the pipette in vertical position and keep the calibration mark at eye level to avoid parallax error. Release the finger pressure slowly so the liquid drains down. The bottom of meniscus is adjusted exactly on the calibration line. Touch the pipette tip to the side wall of waste beaker to remove any hanging drop.

Dispensing the liquid

Bring the pipette to receiving flask. Keep the tip against inner wall with 10 to 45 degree angle. Remove the finger fully and allow the liquid to drain by gravity smoothly. After draining, touch the tip to the wall of receiving flask to transfer last hanging drop.

For TD volumetric pipette and Mohr pipette, the small liquid left in the tip is not blown out. Calibration already includes this hold back volume.

For blow out serological pipette (frosted ring mark at top), use rubber bulb and give a small puff of air to expel the final drop from the tip.

Applications of Pipette

It is used for general sample transfer and solution preparation. It is used to measure and transfer fixed or required volume of chemicals, buffers and reagents for preparing standard solutions.
It is used in titration and analytical chemistry. It is used to deliver accurate amount of titrant or reagents during quantitative analysis and colorimetric assays.
It is used in microbiology and cell culture work. It is used for inoculation of cultures, transferring cells, adding media and for preparing serial dilution to get required concentration.

It is used in molecular biology laboratories. It is used for handling small volumes of DNA, RNA and proteins during PCR set up, nucleic acid extraction, enzyme assay and blotting work.
It is used in clinical diagnostics and pathology. It is used to measure and prepare body fluids like blood, serum and urine for diagnostic assays, immunoassays and pathogen detection tests.
It is used in pharmaceutical quality control and drug discovery. It is used in testing drug formulation, different dose studies, impurity profiling and other QC analysis.

It is used in high throughput screening. It is used to load samples into microplates (96 well or 384 well) for ELISA, spectrophotometer reading and other analytical instruments.
It is used in environmental testing. It is used for measuring and transferring water or soil extract samples for testing pollutants and environmental chemicals.
It is used in food and beverage production. It is used for quality control, ingredient testing and for checking contaminants with accurate liquid measurement.

It is used for educational purpose. It is used in teaching laboratories for training students in liquid handling and volumetric measurement technique.

Advantages of Pipette (Glass Pipettes)

Exceptional chemical resistance. Glass pipette is chemically inert. It can be used for strong acids, bases and organic solvents (hexane, acetone) without getting damaged like plastic.
No chemical leaching. Glass does not leach plasticizers into the solution. It also does not absorb lipophilic compounds, so purity is maintained in trace analysis and sensitive measurements.

High thermal stability. Borosilicate glass pipettes have low thermal expansion. It can withstand sudden temperature change (thermal shock) better than many plastics.
Reusable and sterilizable. Glass pipettes can be sterilized repeatedly by autoclave or dry heat. It does not melt and it can be used again and again if handled properly.
Eco friendly. Since it is reusable, plastic waste from disposable tips is reduced. It supports green chemistry and lab sustainability.

High accuracy and rigidity. Glass volumetric pipettes give very accurate volume between 1 ml to 100 ml. Glass is rigid so it is less affected by hand heat expansion or contraction, the internal volume remains more precise.
Cost effective. For 1 ml to 100 ml range, it is cheaper than costly electronic liquid handling systems. It can be used for long time so overall cost becomes less.
Excellent transparency. Glass is very clear so meniscus can be seen properly. It helps in aligning the meniscus with calibration mark accurately.

Limitations of Pipette (Glass Pipettes)

Fragility and breakage. Glass pipette is very fragile. It can break or chip easily, so careful handling is needed and broken glass disposal is required with safety precautions.
User technique dependent. The accuracy depends a lot on the user skill. Error can come from wrong depth of tip inside liquid, not reading meniscus at eye level (parallax error) and not holding the pipette in vertical position.
Fixed volume problem. Volumetric glass pipette measures only one fixed volume. For different volumes, different pipettes are needed and switching is required.

Cleaning requirement. Glass pipette must be cleaned properly. Grease, protein layer or dried residue can affect wetting and meniscus shape, so volume delivery becomes inaccurate. Some narrow pipettes are very hard to clean and sometimes it is discarded after use.
Drainage and waiting time error. It works by gravity drainage and a thin film remains on inner wall. If waiting time is not followed, the liquid may not drain fully from wall and reading becomes wrong. If TD pipette is blown out by mistake, the delivered volume becomes more than calibrated.
Thermal stress vulnerability. Even though borosilicate glass is stable, uneven heating or sudden change can produce thermal stress and it may shatter. Volumetric glass pipettes also should not be dried at very high temperature and should not be heated directly on hot plate.

Aspiration safety hazard. If mouth pipetting is done, there is risk of ingesting toxic, corrosive or infectious sample. Mouth pipetting is not allowed, so rubber bulb or mechanical filler must be used.

References

Alconox, LLC. (2018, October 17). Cleaning pipettes in the laboratory. TechNotes.
Analytics-Shop. (n.d.). Pipettes – pipette types, materials and areas of application.

ASTM International. (2019, August). Standard specification for glass volumetric (transfer) pipets (ASTM E969-02). Scribd. (Uploaded by J. C. Ferrer Velandia).
Borosil Scientific. (n.d.). Top 10 pipette uses in labs | Accurate liquid handling.
Borosil Scientific. (n.d.). Understanding the role of pipettes in laboratory research and testing.

BRAND GMBH + CO KG. (n.d.). Volumetric measurement.
BRANDTECH Scientific. (2025, October 22). Class A vs. Class B volumetrics – When to spend vs. save.
btlsadmin. (2018, March 23). Air displacement pipettes and how they work. BT Labs.
Cangzhou Yongkang Medical Devices Co., Ltd. (n.d.). Do you use a pipette tip for a serial dilution?

ChemScience. (n.d.). Ultimate guide to pipettes: Everything you need to know.
COLA. (1997, July). LABFACTS 52: Pipettes and their calibration.
Comprehensive metrology and theoretical framework of glass pipettes: Principles, taxonomy, and analytical application. (n.d.).
Environmental Health & Safety. (n.d.). Alternatives to chromic/sulfuric acid for cleaning laboratory glassware.

Exeter Scientific Glass Co. (n.d.). Suggestions for cleaning glassware.
Fisher Scientific. (n.d.). Volumetric pipets.
Frontier, A. (2026). How to: Clean glassware. Department of Chemistry, University of Rochester.
Glassco Laboratory Equipments Pvt. Ltd. (2025, December 8). Handling lab glass.
Glassco Laboratory Equipments Pvt. Ltd. (2025, July 7). Types of pipettes.

Globe Scientific. (n.d.). Difference between ISO and ASTM standard glassware.
Globe Scientific. (n.d.). Understanding laboratory glassware classifications.
Gongdong Medical. (n.d.). What is the difference between a Mohr and serological pipette?
Gongdong Medical. (n.d.). What is the difference between serological and volumetric pipettes?

Horserada, C. J. (n.d.). Folin-Wu method for glucose analysis. Scribd.
Jain, P. (n.d.). Difference class A and class B glassware. Arihantlab.
Khan Academy. (n.d.). Capillary action and why we see a meniscus [Video]. YouTube.

Microlit. (n.d.). Insights archive.
Microlit. (n.d.). What is the Ostwald–Folin pipette?
Microlit USA. (n.d.). What is the use of glass pipettes in laboratory?
Midnapore City College. (n.d.). M.Sc. medical biochemistry lab manual.
NIST. (2014, June). The use of volumetric pipets with NIST handbook 133, checking the net contents of packaged goods.
Pailakian, A. (2026, February 21). Lab glassware cleaning and sterilization: A step-by-step guide. Lab Pro Inc.

Pardillo, M. (n.d.). Types and functions of laboratory pipettes. Scribd.
Pipette.com. (n.d.). Air-displacement / Forward mode.
Pobel. (2024, October 3). What are pipettes used for? The uses of laboratory pipettes.
Pobel. (2024, October 3). What types of laboratory pipettes are there?

Pobel. (n.d.). Volumetric pipettes, class A.
Proctor, J. (2023, March 8). A complete pipette guide. RS Discovery Hub.
Reagecon Diagnostics Ltd. (2003). Volumetric glassware: A Reagecon guide.
Robb, A. (n.d.). Capillary action experiment [Video]. Study.com.
Schurz, C. (n.d.). USP requirements for volumetric instruments. StedaLab / Brand GmbH + Co KG.
Sigma-Aldrich. (n.d.). Lab pipettes.
Simple Business Help LLC. (2021, March 16). Differences between volumetric pipettes and graduated pipettes: Pros, cons and limitations. Lab Pro Inc.

Simson Chemtech. (2025, August 2). Top 10 common uses of pipettes in scientific laboratories.
Techmaster Electronics. (2025, September 11). Pipette calibration standards: Are you up to date?
The Physics Classroom. (n.d.). Capillary action: Why liquids climb walls and rise in tubes.

Thermo Fisher Scientific. (n.d.). Air vs. positive displacement pipettes.
USA Lab. (2025, April 14). Difference class A and class B glassware.
USA Lab. (2025, April 14). Laboratory glassware and their uses.
Valencia College Science Resources. (n.d.). Chemistry lab technique 7: Using a graduated pipet.

Van, T. M. (n.d.). Sugar estimation by Hagedorn-Jensen method. Scribd.
Water Science School. (2018, June 5). Capillary action and water. U.S. Geological Survey.
Westlab. (2017, July 19). What is the difference between TD & TC pipettes?

Wickham, V. (2018, March 16). Laboratory glassware cleaning and storage. Nebraska Water Center.
Wikipedia contributors. (2025, April 27). Air displacement pipette. In Wikipedia, The Free Encyclopedia.
Wikipedia contributors. (2026, April 19). Capillary action. In Wikipedia, The Free Encyclopedia.

Wikipedia contributors. (2024, June 16). Graduated pipette. In Wikipedia, The Free Encyclopedia.
Wikipedia contributors. (2026, March 25). Pipette. In Wikipedia, The Free Encyclopedia.
Zimmerman, N. (n.d.). How to use a bulb pipette [Video]. YouTube.

Pipette (Glass Pipettes) – Principle, Types, Handling, and Uses