A general question regarding contamination: Is it a routine to spray alcohol absolutely on every object that is inserted in the laminar flow cabinet. But how about the flasks that are transported to the microscope for checking stem cell detaching ? I did not see in any video on RU-vid such an operation of spraying the flask before reintroducing it in the laminar flow cabinet !
Hi, Thank you for your video, really helpful for me. Do we need to install the spacer again if we want to do wet loading? you removed the spacer for dry loading, but how about wet loading?
I'm research scientist working in discovery chemistry medicine and medicinal chemistry, I have good experience handling multiple different reactions...... I am looking for PHD is there any chance in your group to work with scholarship
When doing the TLC how do you know the one on the right is the product? The RF is almost the same for the one on the left, but because left is way more concentrated, it had caused streaking.
Thanks for the comments, Mairis! Well, for this particular reaction the RF is almost the same. We have characterized the spot (compound) thoroughly using NMR and Mass spectroscopy techniques.
Dilute your sample. Switch solvents. 1-Chlorobutane is a great alternative to hexane. Similar to 15-25% EtOAc:Hex, but it has a tendency to separate things EtOAc:Hex, will not. Also, it flips the spots, sometimes. This makes it easier, if one wants the now top spot, that was bottom in EtOAc:Hex. Just cause its a new spot, doesn't mean it is the desired product.
In this type of case another eluent system including a protic polar phase like 99:1 - 95:5 DCM/MeOH is useful to remove the streaking by favoring H-bonding of the starting material with the eluent. If you have two spots at the same height, you can also reveal with various stains. Some might be selective of your starting material and allow for proper monitoring. A good start for stains screening can be p-anisaldehyde, CAN, nihnydrin, I2 and KMnO4. If none of them are selective of your starting material, you can still do a MS without forgetting to record a spectra of the starting material as a reference. PS: TLC are better run with a co-spot. Thanks to Tretyakova lab for the content.
