How to Find a Flash Column You Expected?
Flash Column
For organic synthesis and pharmaceutical chemistry, a large amount of compounds should be sifted in the early stage. Once the related active compounds are found, it is necessary to purify this high added value compound. Using Flash column to purify is a common method during this procedure.
There are various kinds of conventional Flash column packing materials of 4 g to 330 g, so how to choose the appropriate specification of the Flash column? This mainly depends on the injection volume.
Definition of Injection Volume
In the process of separation and purification, the injection volume is the critical parameter. The injection volume of sample in preparation and purification usually refers to the maximum amount of sample prepared in order to improve efficiency and reduce the cost of consumables under the condition of ensuring purity and yield.
In preparation and purification process, the injection volume can be divided into two categories: theoretical maximum injection volume and effective maximum injection volume.
The theoretical maximum injection volume refers to only consider the bearing capacity of the packing materials to samples but not the influence of any separation factors. For different kinds of packing materials, because of different matrices, bonding phase and separation principle, the separation ability of packing material per unit weight differs, such as the most common bare silica and C18 silica gel whose bonded phase is the silanol group and the C18. The theoretical maximum injection volume of bare silica gel is 1/10 of the amount of silica gel, and the theoretical maximum injection volume of silica gel packing material of C18 is 1/50 of the amount of packing material.
In the practical use, resolution and dissolving degree will influence our injection situation. Therefore, resolution refers to the effective maximum injection volume in the daily life.
Influence of resolution and dissolving degree to injection volume mainly decides the way of overloaded injection and necessity of overloaded injection.
First is resolution, if the resolution of objective compounds and impurities is high, injection volume can be increased. With the increasing injection volume, resolution decreases until it influences the requirements of recovery rate and purification. If the resolution is not expected, decrease the injection volume. Therefore,resolution decides whether overloaded injection method should be used.
After resolution is dissolving degree which decides the way of overloading injection. If samples have great dissolving degree, overloaded concentration is priority. Increase the sample concentration while the injection volume keeps the same, and sample peak turns symmetrical Gaussian shape to triangle shape. Peak broadening is small with great separation effect. If the dissolving degree of sample is poor, volume overloading can be selected. Increase the injection volume, the peak height will be stable and peak will be broadened. But risk exists when choosing volume overloading.
Fig 1 Different injection modes and peak shape
How to choose a Flash column according to the injection volume?
How to choose the injection volume according to the Flash column specification?
If you can not directly judge the injection volume or select the column specification, you can choose the Flash column specifications and sample injection volume listed in the instructions of the medium and low pressure Welch WelFlash column as a reference.
| Specification | 4g | 2g | 25g | 40g | 80g | 120g | 220g | 330g |
| Injection volume1(g) | 0.01-0.02 | 0.03-0.06 | 0.0M.1 | 0.1-0.2 | 0.2-0.4 | 0.3-0.6 | 0.5-1.0 | 0.75-1.5 |
| Injection volume2(g) | 0.02-0.08 | 0.06-0.24 | 0.1-0.4 | 0.2-0.8 | 0.4-1.6 | 0.6-2.4 | 1.0-4.0 | 1.5-6.0 |
| Injection volume3(g) | 0.08-0.4 | 0.24-1.2 | 0.4-2.0 | 0.8-4.0 | 1.6-8.0 | 2.4-12.0 | 4.0-22.0 | 6.0-33.0 |
| Column volume | 8mL | 24mL | 40mL | 80mL | 160mL | 240mL | 400mL | 600mL |
| Min. flow rate | 5mL/min | 8mL/min | 10mL/min | 20mL/min | 25mL/min | 35mL/min | 45mL/min | 50mL/min |
| Max.flow rate | l8mL/min | 20mL/min | 25mL/min | 40mL/min | 50mL/min | 80mL/min | 90mL/min | 100mL/min |
| Pressure | Max. Pressure: 200psi |
Injection volume 1: injection volume ΔCV=1
Injection volume2: injection volume ΔCV=2
Injection volume3: injection volume ΔCV=6
Fig 2 Recommended injection volume in WelFlash instructions
Welch R & D produces high performance packing materials, providing high quality HPLC columns and preparation columns, aiming to solve various separation and purification application problems for you. The company's WelFlash medium-low pressure prepared column provides many matrices, such as full porous spherical silica gel, amorphous silica gel, alumina, polystyrene-divinylbenzene (PSDVB) and other substrates, the bonded phase is bountiful. It adopts polypropylene cylinder which is durable for multiple use with standard Luer-Lock export and import, compatible with a variety of rapid preparative systems.
Spherical 20-40μm silica gel
| P/N | Specification |
| 00001-03011 | WelFlash® SiO2-l, 4g, 20 pcs/pk |
| 00001-03021 | WelFlash® SiO2-l, 12g, 18 pcs/pk |
| 00001-03031 | WelFlash® SiO2-l, 25g, 12 pcs/pk |
| 00001-03042 | WelFlash® SiO2-l, 40g, 10 pcs/pk |
| 00001-03053 | WelFlash® SiO2-l, 80g, 10 pcs/pk |
| 00001-03063 | WelFlash® SiO2-l, 120g, 10 pcs/pk |
| 00001-03075 | WelFlash® SiO2-l, 220g, 6 pcs/pk |
| 00001-03084 | WelFlash® SiO2-l, 330g, 4 pcs/pk |
Spherical 40-70μm silica gel
| P/N | Specification |
| 00001-04011 | WelFlash® SiO2-l, 4g, 20 pcs/pk |
| 00001-04021 | WelFlash® SiO2-l, 12g, 18 pcs/pk |
| 00001-04031 | WelFlash® SiO2-l, 25g, 12 pcs/pk |
| 00001-04042 | WelFlash® SiO2-l, 40g, 10 pcs/pk |
| 00001-04053 | WelFlash® SiO2-l, 80g, 10 pcs/pk |
| 00001-04063 | WelFlash® SiO2-l, 120g, 10 pcs/pk |
| 00001-04075 | WelFlash® SiO2-l, 220g, 6 pcs/pk |
| 00001-04084 | WelFlash® SiO2-l, 330g, 4 pcs/pk |
Spherical 20-40μm C18
| P/N | Specification |
| 00002-03011 | WelFlash® C18-1, 4g, 20 pcs/pk |
| 00002-03021 | WelFlash® Cl 8-1, 12g, 18 pcs/pk |
| 00002-03031 | WelFlash® Cl8-1, 25g, 12 pcs/pk |
| 00002-03042 | WelFlash® Cl8-1, 40g, 10 pcs/pk |
| 00002-03053 | WelFlash® Cl8-1, 80g, 10 pcs/pk |
| 00002-03063 | WelFlash® Cl 8-1, 120g, 10 pcs/pk |
| 00002-03075 | WelFlash® C18-1, 220g, 6 pcs/pk |
| 00002-03084 | WelFlash® C18-1, 330g, 4 pcs/pk |
Spherical 40-70μm C18
| P/N | Specification |
| 00002-04011 | WelFlash® C18-1, 4g, 20 pcs/pk |
| 00002-04021 | WelFlash® C18-1, 12g, 18 pcs/pk |
| 00002-04031 | WelFlash® C18-1, 25g, 12 pcs/pk |
| 00002-04042 | WelFlash® C18-1, 40g, 10 pcs/pk |
| 00002-04053 | WelFlash® C18-1, 80g, 10 pcs/pk |
| 00002-04063 | WelFlash® C18-1, 120g, 10 pcs/pk |
| 00002-04075 | WelFlash® C18-1, 220g, 6 pcs/pk |
| 00002-04084 | WelFlash® C18-1, 330g, 4 pcs/pk |
Spherical 20-40μm Phenyl
| P/N | Specification |
| 00003-03011 | WelFlash®Phenyl, 4g, 20 pcs/pk |
| 00003-03021 | WelFlash® Phenyl, 12g, 18 pcs/pk |
| 00003-03031 | WelFlash®Phenyl, 25g, 12 pcs/pk |
| 00003-03042 | WelFlash® Phenyl, 40g, 10 pcs/pk |
| 00003-03053 | WelFlash®Phenyl, 80g, 10 pcs/pk |
| 00003-03063 | WelFlash®Phenyl, 120g, 10 pcs/pk |
| 00003-03075 | WelFlash®Phenyl, 220g, 6 pcs/pk |
| 00003-03084 | WelFlash®Phenyl, 330g, 4 pcs/pk |
Spherical 20-40μm CN
| P/N | Specification |
| 00004-03011 | WelFlash® CN, 4g, 20 pcs/pk |
| 00004-03021 | WelFlash® CN, 12g, 18 pcs/pk |
| 00004-03031 | WelFlash® CN, 25g, 12 pcs/pk |
| 00004-03042 | WelFlash® CN, 40g, 10 pcs/pk |
| 00004-03053 | WelFlash® CN, 80g, 10 pcs/pk |
| 00004-03063 | WelFlash® CN, 120g, 10 pcs/pk |
| 00004-03075 | WelFlash® CN, 220g, 6 pcs/pk |
| 00004-03084 | WelFlash® CN, 330g, 4 pcs/pk |
Spherical 20-40μm NH2
| P/N | Specification |
| 00005-03011 | WelFlash® NH2, 4g, 20 pcs/pk |
| 00005-03021 | WelFlash® NH2, 12g, 18 pcs/pk |
| 00005-03031 | WelFlash® NH2, 25g, 12 pcs/pk |
| 00005-03042 | WelFlash® NH2, 40g, 10 pcs/pk |
| 00005-03053 | WelFlash® NH2, 80g, 10 pcs/pk |
| 00005-03063 | WelFlash® NH2, 120g, 10 pcs/pk |
| 00005-03075 | WelFlash® NH2, 220g, 6 pcs/pk |
| 00005-03084 | WelFlash® NH2, 330g, 4 pcs/pk |
Spherical 20-40μm SAX
| P/N | Specification |
| 00007-03011 | WelFlash® SAX, 4g, 20 pcs/pk |
| 00007-03021 | WelFlash® SAX, 12g, 18 pcs/pk |
| 00007-03031 | WelFlash® SAX, 25g, 12 pcs/pk |
| 00007-03042 | WelFlash® SAX, 40g, 10 pcs/pk |
| 00007-03053 | WelFlash® SAX, 80g, 10 pcs/pk |
| 00007-03063 | WelFlash® SAX, 120g, 10 pcs/pk |
| 00007-03075 | WelFlash® SAX, 220g, 6± pcs/pk |
| 00007-03084 | WelFlash® SAX, 330g, 4 pcs/pk |