A volumetric flask is the reference glassware for making standard solutions. Class A flasks carry tighter tolerance than Class B, but the number on the certificate is only useful if the flask is used and cleaned correctly.
Class A is the default for analytical standards, QC and methods that specify tight volumetric tolerance. Class B is acceptable for general preparation where its tolerance is fit for purpose. Do not assume that every printed flask is Class A — check the marking and the certificate.
| Nominal volume | Typical Class A tolerance | Common use |
|---|---|---|
| 5 mL | ±0.02 mL | Trace standards |
| 10 mL | ±0.02 mL | Small standards |
| 20 / 25 mL | ±0.03 mL | Method development |
| 50 mL | ±0.05 mL | General standards |
| 100 mL | ±0.10 mL | Routine QC |
| 250 mL | ±0.12 mL | Larger standards |
| 500 mL | ±0.20 mL | Bulk standards |
| 1000 mL | ±0.30 mL | Large-volume preparation |
Tolerance values vary by standard and manufacturer. Use the value on the flask certificate for method validation.
Amber flasks protect light-sensitive standards; clear flasks make the meniscus easier to see. Amber glass is not a substitute for a dark cabinet when the compound is highly photolabile.
Volumetric glassware is calibrated at a stated temperature, commonly 20 °C. If your laboratory is significantly warmer or colder, let the flask and solvent equilibrate before bringing to the mark. Do not calibrate by adding solvent to a hot flask.
Volumetric flasks are not storage bottles. Remove residues promptly, avoid abrasive brushes, and do not dry in an oven above the calibration temperature. Store stoppered and upright to protect the neck and mark.
We supply Class A volumetric flasks from 5 mL to 1000 mL, in clear and amber glass, with PP or glass stoppers. Tell us the volume, tolerance and whether a certificate is required.
Use Class A when the method requires tight volumetric tolerance or you are preparing analytical standards. Class B may be acceptable for general preparation.
Commonly 20 °C. Let the flask and solvent equilibrate before bringing to the mark, especially in a warm laboratory.
It is not recommended. Volumetric flasks are calibrated vessels; use a reagent bottle for storage.
Yes, amber Class A flasks are available in common sizes. Confirm the volume and stopper type.
Use a suitable laboratory detergent and a soft brush, rinse thoroughly, and avoid abrasive cleaning or high-temperature drying.
Tell us the sizes, quantities and sterility requirements. We reply within 2 hours on business days.
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