An interesting question, at least to me. Depending on the detector brand, some mass spectrometer manufacturers recommend acetonitrile while others recommend methanol. Is there a real difference between these solvents?
In this post I look at how acetonitrile and methanol compare when used with an APCI source.
Continue reading Does mass detection make-up solvent choice matter?
I am always grateful for the feedback I get from my blog readers. Today’s blog is in response for multiple requests for tips on purifying complex mixtures and suggestions for alternative sample loading techniques.
In this post, I will attempt to address both, to some degree anyway, with a single example using a scavenger resin.
Continue reading In-line scavenging simplifies flash column chromatography reaction mixture purification
For chemists preferring or needing to dry load their crude sample mixtures to get an acceptable flash purification result, using the right ratio of sample to sorbent can be quite important. Too much sample and solubility issues can ensue, too little sample and significant band broadening occurs, reducing the separation quality.
In this post, I propose an acceptable ratio range based on my own experimental data.
Continue reading What is the optimal sample to sorbent ratio for dry loading in flash column chromatography?
Over the past several years, automated flash chromatography has evolved to include in-line mass detection. Typically, these single-quadrupole mass detectors are outfitted with either an atmospheric pressure chemical ionization source (APCI) or an electrospray chemical ionization source (ESI). While this technical advance in flash chromatography has helped chemists detect and isolate pure compounds with a known molecular weight, verifying the identity of that compound can sometimes be a challenge as the detected mass may not match that which you expect due to fragmentation and/or adduct formation.
In this post I will offer some assistance in determining adducts and fragments.
Continue reading Using adducts and fragments to identify compounds in mass-directed flash chromatography
APCI (atmospheric pressure chemical ionization) and ESI (electrospray ionization) are the two most frequently utilized mass detection tools for automated flash chromatography. In a previous post, I discussed differences between the two detectors and the compound types best suited for each source.
Because these two sources ionize differently, there are cases when additives are needed in the make-up solvent and cases when they should not. In this post, I will show the impact that adding a buffer or acid has on APCI detection.
Continue reading What impact do buffers have on APCI mass detection?
With reversed-phase flash column chromatography becoming increasingly popular for routine purification, understanding how to make the cartridges last (since they cost more) is important to know.
In this post I will mention a few tips to prolong reversed-phase cartridge life.
Continue reading 5 Tips on extending reversed-phase flash chromatography cartridge life