This is an interesting question that does not have a straightforward answer. In fact, there are many materials that are potentially useful sorbents for dry loading crude mixtures. Some of the more popular are silica, diatomaceous earth (e.g. ISOLUTE® HM-N, Celite®), alumina, and Florisil®. The sorbent choice can influence your purification results because each of the available media have different chemistry and capacity. In most cases, sample/sorbent reactivity really is not a major concern, though it can occur. What is important is the sorbent’s capacity to adsorb/absorb all of your sample and the ratio of your crude sample to the amount of dry load sorbent.
Dry loading crude samples for flash purification typically works better than liquid loading, especially for challenging purifications. In this post, I discuss how the ratio of crude sample to dry load sorbent impacts purification performance.
When it comes time to purify your reaction mixture or natural product extract, you have a choice to make. Should you simply load your dissolved sample onto your flash column or take the extra step to adsorb your mix onto a sorbent and dry it before loading? The choice can have a major impact on your results.
In this post, I will share results of work I conducted in my lab, comparing liquid and dry loading a reaction mixture that containing eight major components.
UV detection and fractionation is ubiquitous in flash chromatography. It is the default methodology used to detect and collect eluting compounds. Today’s flash chromatography systems offer UV-triggered fractionation on one, two, or a range of wavelengths in order to either increase fractionation specificity, yield, or increase sensitivity. In this post, I will discuss the value of incorporating fractionation based on a wavelength range and two selectable individual wavelengths.
For many chemists, flash chromatography with UV-triggered fractionation is part of their everyday workflow. Prior to flash chromatography, the reaction mixtures are either analyzed by TLC, analyzed by LC-MS, or both to ensure the targeted product has been synthesized. But, what if the reaction created a lot of by-products? How do you find your product in a sea of impurities? In this post, I will discuss how using a flash purification system with an in-line mass detector will simplify flash purification and isolate the target molecule or molecules.
On December 6th, 2018, Bob Bickler, Senior Technical Specialist, recorded a webinar on How To Be Successful with Flash Chromatography. To learn more, read the description below as well as watch the recording!
Organic reactions are generally inefficient, which means that crude reaction mixtures require work-up and purification to remove by-products and unreacted starting materials and/or catalysts. The goal in pharmaceutical research is to isolate the target compound with required purity and yield to be able to progress to the next synthetic sequence or biological testing with confidence. But the process of purification is viewed by synthetic chemists as a ‘means-to-an-end’ and the more rapidly and reliably the purification step can be performed the better. Easy enough to state, but hard to achieve when you need to be certain of purity and yield in a single, rapid purification attempt. As we will see here, flash column chromatography can help you achieve this.
First, join me on a flashback to my past as a discovery chemist just fresh out of grad school and eager to make a difference in pharmaceutical research. I was advised by my boss to model my behavior after a colleague and labmate with a reputation of being highly productive and successful. I was also informed that ‘chemist productivity’ was measured by 1) the number of compounds (of sufficient quantity and quality) he/she registered in the company’s database and 2) meeting project milestones.