Volumetric Flask
What is a Volumetric Flask?
In 1892, Dewar invented the world's first volumetric flask, known as the "Dewar Flask." A volumetric flask is a laboratory glassware designed for precise liquid measurement. It features a flat bottom, a long narrow neck, and a single calibration line for accurate volume determination. These flasks are made of borosilicate glass or plastic to ensure durability. The volumetric flask, also known as measuring flask or graduated flask, is lightweight, compact, and chemical resistant.
What Are Volumetric Flasks Used For?
Volumetric flasks are used to prepare solutions with exact concentrations. Common applications include dilutions, standard solution preparation, and titration setups in chemical analysis, biology, and pharmaceutical research.
Classification of Volumetric Flasks:
- Class A: Designed for the highest accuracy with tighter tolerance limits. Each flask is individually calibrated and features a unique serial number for traceability. Clear glass variants have a blue print, while amber variants have white. These flasks are ideal for precision applications and come with calibration certifications.
- Class B: Used for general purposes with a lower level of accuracy. These flasks have white print and lack individual calibration. Commonly used in schools, they are suitable for less demanding tasks.
How to Calibrate a Volumetric Flask
To calibrate a volumetric flask:
- Weigh the empty, dry flask.
- Fill upto the calibration line with distilled water at a standard temperature (usually 20°C).
- Weigh the filled flask.
- Subtract the weight of the empty flask to determine the water's mass, then use the water’s density to confirm the volume.
Manufacturing Standards
Volumetric flasks are produced under three primary standards:
- ASTM (American Society for Testing and Materials)
- ISO (International Organization for Standardization)
- USP (United States Pharmacopeia)
Glassco, India's first glassware manufacturing plant, produces flasks adhering to all three standards under one roof.
How Accurate Is a Volumetric Flask?
Volumetric flasks are highly accurate, with tolerance levels as low as ±0.02 mL for smaller volumes (e.g., 10 mL) and ±0.30 mL for larger volumes (e.g., 1 L). This makes them ideal for precision work in quantitative analysis.
Types of Volumetric Flasks
Volumetric flasks are classified based on their certification and specific applications. The primary types meeting ASTM E228 standards include:
Individually Certified Flasks with a Glass Stopper
- Designed for high precision, these flasks are individually calibrated.
- They come with a glass stopper for secure sealing and prevent contamination.
Batch Certified Flasks with a Glass Stopper
- These flasks are batch-calibrated, offering consistent accuracy for routine tasks.
- The glass stopper ensures safe storage of solutions.
Batch Certified Flasks with a Snap Cap
- These flasks use a snap cap instead of a stopper, providing convenience for frequent use.
- Ideal for laboratories requiring less stringent accuracy.
Individually Certified Flasks with Amber-Colored Glass
- These flasks are specifically designed to protect light-sensitive solutions.
- Individually calibrated, they ensure precision while maintaining solution stability against light exposure.
These types cater to various precision requirements and laboratory applications, ranging from routine tasks to highly sensitive procedures.
How to Use a Volumetric Flask?
To use a volumetric flask:
- Add the solute or substance to the flask.
- Fill with solvent to just below the calibration line.
- Adjust the level precisely to the calibration mark by adding solvent dropwise.
- Mix thoroughly by inverting the flask several times to ensure uniform distribution.
Size of Volumetric Flasks
Sizes range from 2ml volumetric flask to 5000ml volumetric flask. Common sizes include 10 mL, 25 mL, 50 mL, 100 mL, 250 mL, 500 mL, 1 L, and 2 L. Each flask is designed to measure a precise volume with high accuracy, marked by a calibration line on the neck. Small flasks are ideal for preparing costly and precious drugs. In contrast, large flasks are used in pharmaceutical labs for production batches and specialized flasks are used in industrial analytical and food chemistry to combine multiple accurately measured volumes. Glassco manufactures all sizes, meeting diverse laboratory needs.
Why Are Volumetric Flasks More Accurate?
Volumetric flasks provide superior accuracy because they have a single, precisely etched calibration line, ensuring minimal volume error. Their narrow neck reduces measurement uncertainty by allowing finer adjustments to the liquid level.
What Is the Line on a Volumetric Flask Called?
The line on a volumetric flask is called the "calibration mark" or "graduation line." It indicates the exact volume the flask is designed to contain when filled to that level.
- Accurate
- Hollow Design
- Imprints in 3 different variants - Blue, White, and Amber
- Meniscus Mark
- Reliable
- Available in both Plastic and Glass
- Batch Certificate
- Individual Certificate
- Chemical Resistant
- Compact
- Durable
Cleaning: Before using a volumetric flask, rinse it with the solvent, which is used to prepare the solution. After the completion of the experiment, empty the flask, and wash it with warm soapy water. Scrub it with a brush if required. Then rinse it under tap water 3-4 times. Dry the flask with a clean cotton cloth.
Storage: A volumetric flask should be stored in a dry place in a box to prevent dirt. It is preferred to keep them in a cupboard. Also, the volumetric flasks should be stored with their stoppers so that they are not lost. It is preferred not to store solutions in a volumetric flask as it may corrode and affect the flask’s accuracy.
Life: A volumetric flask made up of Borosilicate Glass can be used for up to 10 long years of constant use. It should be adequately taken care of, keeping in mind its storage and cleanliness.
- Keep the lab/room temperature at 20º C or close to it because the volumetric flasks are calibrated for use at this temperature.
- Thoroughly clean the volumetric flask before and after using it.
- Before using a volumetric flask, scrutinize it by checking cracks or scratches on the glass.
Each volumetric flask has its unique Individual Calibration Certificate stating the standard ratio of volumes in the flask. The stack of measuring flasks is identified by their Batch Calibration Certificate, signifying that the lot has been duly checked and suitable for sale.
Apart from this, the volumetric flask has a Calibration Certificate from NABL (National Accreditation Board for Testing and Calibration Laboratories), which states the standard weights of the flask. The NABL logo contains a unique ULR (Unique Laboratory Report) number, which identifies the laboratory where the calibration process occurs.
- Glassco furnishes Class A volumetric flasks.
- The volumetric flask at Glassco comprises solid Borosilicate Glass 3.3, which is shock-free and chemical resistant.
- Glassco’ s volumetric flasks, when used with a flower power stopper, ensure no leakage.
- The flasks produced at Glassco come with an optional Bumper Guard to prevent breakage.
- The blue and amber color meniscus mark on Glassco’ s Flasks helps to read the solutions more clearly than the diamond cut meniscus.
- The prints on the glass pass acid boiling, scratch, and tape peel off tests.
- Glassco provides flasks with all kinds of mouth openings as per the customer requirement, which is customizable other than standards.
- The volumetric flasks at Glassco are of superfine Glass quality.
Glassco’ s Volumetric Flask is used for preparing high precision medicines which, at times, requires heating and shaking. DAN Logitech’s Incubator Shaker is the instrument best suited for Glassco’ s Volumetric Flask. It ensures a consistent and uniform mixing of liquids in flasks.
Glassco has introduced its QR Coded Volumetric Flask, which is very useful for the research and development department where calibration certificate is a winning thing. Glassco is the first laboratory equipment manufacturing company from India to pioneer the QR Coded Volumetric Flask worldwide.
The volumetric flask has a permanent QR Code which, when scanned, directs you to the web page of the product providing its certification along with the complete information about the flask. At the time of the audit, it often becomes difficult for a person to fetch each flask’s certificate. In that case, the QR Code on the volumetric flask makes it easy, simple, and handy to download the certificate and verify it. One can easily save and print the certificate.
The second version of the QR Coded Volumetric Flask was introduced by Glassco to make it LIMS compatible. Glassco has collaborated with the Caliber LIMS to make it more paperless laboratories using scannable glassware.
