Microscale Purification

µ-scale High-throughput experiments (HTE) can produce very small quantities of the material, in which case handling them in vials may not be practical. The basic Purification workflow and the steps, though, stay the same as regular purification done with HPLC.

Because it’s plate-based, there’s no way of weighing each individual fraction after drying it. So how do we quantify the pure compound? For that we can use Universal HPLC detectors. Such detectors produce the signal proportional to the concentration regardless of the actual compound. So the concentrations of different compounds can be compared.

One of such detectors is Charged Aerosol Detector (CAD). It’s possible to create calibration curves using standards which don’t necessarily resemble the compounds that we purify.

In practice though, even universal detectors have their limitations. E.g. it’s possible that low-mass compounds produce smaller signal than their high-mass counterparts. So this method isn’t necessarily as precise as weighing.