As a lab professional, you may have come across the acronyms ISO and ASTM when working with laboratory supplies such as glassware. However, you may not know precisely what these classifications mean and what the difference is between ISO and ASTM standards.

Here’s what you need to know about the difference between ISO and ASTM standards and why ASTM standards are preferable for laboratory applications.

What is an ISO Standard Classification?

The International Organization for Standardization (ISO) sets forth methods for the “testing, calibration and use of volumetric instruments made from glass” so that laboratory professionals can achieve a high level of accuracy while carrying out their processes. A standard piece of laboratory glassware that has been given an ISO certification has met these standard ISO requirements. ISO classifications tend to be more common in Europe and Asia.

What is an ASTM Standard Classification?

Similar to the ISO, the American Society for Testing and Materials (ASTM) also sets forth methods of testing and calibration of volumetric glassware so that laboratory professionals can be assured of a certain quality and tolerance range when using a product. ASTM standards are more common in the United States, and regulators such as the U.S. Food and Drug Administration (FDA) adhere to ASTM guidelines when it comes to activities within the pharmaceutical industry.

What is the Difference between ISO and ASTM Standard Glassware?

While ISO and ASTM standards both take into consideration similar qualities when calibrating glassware, they vary as to the global regions in which they are adopted. Additionally, ASTM classifications differentiate volumetric glassware performance even further, dividing products such as volumetric flasks, graduated cylinders, and beakers into two distinct categories: Class A and Class B.

Products that are given Class A status have met rigorous ASTM standards for a specific range of volumetric tolerance, and many include a certification that indicates their specific testing and alignment with these standards and a serial number for easier manufacturing traceability. Products that are given a Class B status have also met rigorous standardization requirements. However, their tolerance is double that of Class A glassware.

Because of the careful attention to precision and the guarantee of high accuracy inherent in ASTM standardization (particularly Class A), ASTM-certified glassware is generally regarded as preferable for laboratory applications. Compared to the ISO standards set forth for laboratory glassware, ASTM standards have a narrower range of tolerability and, therefore, the highest accuracy available in a laboratory setting.

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(This blog was originally posted by Globe Scientific)