Rice researchers find using certain stir bars can create laboratory errors
The stirrers that mix cream into your coffee probably don’t make much difference to the drink. But in a chemistry lab, it turns out using the wrong stirrer can skew the science.
Rice University scientists have determined that stir bars made of PTFE, more commonly known as Teflon, can introduce errors into a standard lab reaction used to manipulate the properties of carbon or boron-nitride nanotubes.
Stir bars are pellet-like rods of ferromagnetic metal covered in PTFE that sit in the bottom of a beaker and are turned by a rotating magnetic field. They allow a solution to be mixed in a closed flask without manual stirring.
The Rice lab of Angel Martí published a paper in the American Chemical Society journal ACS Omega outlining what happens when PTFE stir bars are used to functionalize nanotubes through Billups-Birch reduction, a long-used reaction developed in part by Rice Professor Emeritus of Chemistry Edward Billups that frees electrons to bind with other atoms.
Reduction is often used to make nanotubes more amenable to functionalization, the process of customizing them for applications by adding molecules like proteins. That can be as simple as dispersing nanotubes in a chemical bath laden with the molecules you want to add. Billups-Birch is one such method, a one-step process used to functionalize nanotubes with a variety of molecules, according to the researchers.
Rice University chemists discovered that stir bars covered in PTFE, also known as Teflon, react with chemicals in an unexpected way during the modification of nanotubes through Billups-Birch reduction. The bars that start out (and usually stay) white turn black in the solution and alter the results. Photo by Brandon Martin
When they used it to modify nanotubes of boron-nitride, the researchers were surprised to see their tubes turn gray, while …