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Laboratory Glassware - What Are TD (To Deliver) and TC (To Contain), and How Do They Differ?
Laboratory Glassware - What are TD (To Deliver) and TC (To Contain), and How Do They Differ?
At Globe Scientific, we’re committed to advancing scientific research by supporting laboratory professionals. Central to this mission is being clear and concise about our high-quality glassware offerings, as well as the definitions involved.
“To deliver” (TD) and “To contain” (TC) are descriptors that you may have come across in the lab. Here’s what you need to know about these monikers, and why they matter.
Defining Volumetric Container Roles
Have you ever gotten down to the very end of a toothpaste tube, squeezing and rolling the tail vigorously to extract the last bit? Even as you crank out the final smidge of paste, you know that the tube still contains more in the nozzle that you won’t be able to access. Imagine what would happen if you squeezed the entire tube of toothpaste into a cup and measured the resulting volume. The volume of toothpaste that filled the original tube would be greater than the volume of toothpaste that you were able to squirt into the cup.
This analogy describes the situation that TD and TC volumetric glassware labels address. Volumetric glassware that is meant to deliver a volume of substance (TD) will be calibrated to deliver a specific volume. However, it will hold more (i.e., the capacity of the entire toothpaste tube). In contrast, laboratory glassware meant to receive a substance (TC) will be calibrated to contain a specific volume. However, if it is poured out, it will deliver less. For example, a graduated cylinder that is meant to deliver 50ml will hold slightly more volume to account for what is left behind. A flask that is meant to contain 10ml will hold exactly that amount, but if you pour it into another receptacle, less than 10ml will be delivered.
The terms TD and TC are created to help account for the small amount of volume that always remains. This marginal difference can have huge implications when it comes to precise measurements, which is why there is specific glassware for each purpose.
The Bottom Line on TD and TC
Here’s the bottom line when ordering glassware:
- TD means “to deliver,” and traditionally includes glassware that is intended to be transitional, transporting a substance into a more definitive TC container. Items marked with a TD include graduated cylinders.
- TC means “to contain,” and traditionally includes containers that are meant for longer-term housing of a substance, such as volumetric flasks.
The TD-to-TC relationship is unilateral: TD goes into TC. Consider the lab processes and workflow when recommending or purchasing laboratory glassware.
Globe Glass™ Laboratory Glassware
Designed to meet the needs of the most demanding laboratory professionals, Globe GlassTM laboratory glassware sets the standard for performance and packaging in the glassware marketplace. Top quality borosilicate glass delivers outstanding strength, durability, and chemical resistance. Superior GlassGuardTM packaging has been engineered to ensure that Globe Glass products arrive at their destination intact and ready for use each and every time. Globe Glass beakers, Erlenmeyer flasks, volumetric flasks, graduated cylinders, and media bottles are offered in sizes most used in laboratories everywhere. Check out our laboratory glassware line, today!