Flash Column

For organic synthesis and pharmaceutical chemistry, a largr 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 mateials 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 injeciton 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 incresing injection volume, resolution decreases until it influences the requirements of recoverary rate and purificaiton. 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 concentraiton is priority. Increase the sample concentration while the injeciton 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 broaded. 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.

Injection volume1(g)0.01-0.020.03-0.060.0M.10.1-0.20.2-0.40.3-0.60.5-1.00.75-1.5
Injection volume2(g)0.02-0.080.06-0.240.1-0.40.2-0.80.4-1.60.6-2.41.0-4.01.5-6.0
Injection volume3(g)0.08-0.40.24-1.20.4-2.00.8-4.01.6-8.02.4-12.04.0-22.06.0-33.0
Column volume8mL24mL40mL80mL160mL240mL400mL600mL
Min. flow rate5mL/min8mL/min10mL/min20mL/min25mL/min35mL/min45mL/min50mL/min
Max.flow ratel8mL/min20mL/min25mL/min40mL/min50mL/min80mL/min90mL/min100mL/min
PressureMax. Pressure: 200psi
Note:injection volume:ACV=l/Rf1-1/Rf2; Matrix:silica gel 40-60μm
Injection volume 1: injection volume ACV=1
Injection volume2: injection volumeACV=2
Injection volume3: injection volumeACV=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
00001-03011WelFlash® SiO2-l, 4g, 20 pcs/pk
00001-03021WelFlash® SiO2-l, 12g, 18 pcs/pk
00001-03031WelFlash® SiO2-l, 25g, 12 pcs/pk
00001-03042WelFlash® SiO2-l, 40g, 10 pcs/pk
00001-03053WelFlash® SiO2-l, 80g, 10 pcs/pk
00001-03063WelFlash® SiO2-l, 120g, 10 pcs/pk
00001-03075WelFlash® SiO2-l, 220g, 6 pcs/pk
00001-03084WelFlash® SiO2-l, 330g, 4 pcs/pk

Spherical 40-70μm silica gel

00001-04011WelFlash® SiO2-l, 4g, 20 pcs/pk
00001-04021WelFlash® SiO2-l, 12g, 18 pcs/pk
00001-04031WelFlash® SiO2-l, 25g, 12 pcs/pk
00001-04042WelFlash® SiO2-l, 40g, 10 pcs/pk
00001-04053WelFlash® SiO2-l, 80g, 10 pcs/pk
00001-04063WelFlash® SiO2-l, 120g, 10 pcs/pk
00001-04075WelFlash® SiO2-l, 220g, 6 pcs/pk
00001-04084WelFlash® SiO2-l, 330g, 4 pcs/pk

Spherical 20-40μm C18

P/N Specification
00002-03011WelFlash® C18-1, 4g, 20 pcs/pk
00002-03021WelFlash® Cl 8-1, 12g, 18 pcs/pk
00002-03031WelFlash® Cl8-1, 25g, 12 pcs/pk
00002-03042WelFlash® Cl8-1, 40g, 10 pcs/pk
00002-03053WelFlash® Cl8-1, 80g, 10 pcs/pk
00002-03063WelFlash® Cl 8-1, 120g, 10 pcs/pk
00002-03075WelFlash® C18-1, 220g, 6 pcs/pk
00002-03084WelFlash® C18-1, 330g, 4 pcs/pk

Spherical 40-70μm C18

P/N  Specification
00002-04011WelFlash® C18-1, 4g, 20 pcs/pk
00002-04021WelFlash® C18-1, 12g, 18  pcs/pk
00002-04031WelFlash® C18-1, 25g, 12 pcs/pk
00002-04042WelFlash® C18-1, 40g, 10 pcs/pk
00002-04053WelFlash® C18-1, 80g, 10 pcs/pk
00002-04063WelFlash® C18-1, 120g, 10 pcs/pk
00002-04075WelFlash® C18-1, 220g, 6 pcs/pk
00002-04084WelFlash® C18-1, 330g, 4 pcs/pk

Spherical 20-40μm Phenyl

P/N Specification
00003-03011WelFlash®Phenyl, 4g, 20 pcs/pk
00003-03021WelFlash® Phenyl, 12g, 18 pcs/pk
00003-03031WelFlash®Phenyl, 25g, 12 pcs/pk
00003-03042WelFlash® Phenyl, 40g, 10 pcs/pk
00003-03053WelFlash®Phenyl, 80g, 10 pcs/pk
00003-03063WelFlash®Phenyl, 120g, 10 pcs/pk
00003-03075WelFlash®Phenyl, 220g, 6 pcs/pk
00003-03084WelFlash®Phenyl, 330g, 4 pcs/pk

Spherical 20-40μm CN

P/N  Specification
00004-03011WelFlash® CN, 4g, 20 pcs/pk
00004-03021WelFlash® CN, 12g, 18  pcs/pk
00004-03031WelFlash® CN, 25g, 12 pcs/pk
00004-03042WelFlash® CN, 40g, 10 pcs/pk
00004-03053WelFlash® CN, 80g, 10 pcs/pk
00004-03063WelFlash® CN, 120g, 10  pcs/pk
00004-03075WelFlash® CN, 220g, 6 pcs/pk
00004-03084WelFlash® CN, 330g, 4 pcs/pk

Spherical 20-40μm NH2

P/N Specification
00005-03011WelFlash® NH2, 4g, 20 pcs/pk
00005-03021WelFlash® NH2, 12g, 18 pcs/pk
00005-03031WelFlash® NH2, 25g, 12 pcs/pk
00005-03042WelFlash® NH2, 40g, 10 pcs/pk
00005-03053WelFlash® NH2, 80g, 10 pcs/pk
00005-03063WelFlash® NH2, 120g, 10  pcs/pk
00005-03075WelFlash® NH2, 220g, 6 pcs/pk
00005-03084WelFlash® NH2, 330g, 4 pcs/pk

Spherical 20-40μm SAX

00007-03011WelFlash® SAX, 4g, 20 pcs/pk
00007-03021WelFlash® SAX, 12g, 18 pcs/pk
00007-03031WelFlash® SAX, 25g, 12 pcs/pk
00007-03042WelFlash® SAX, 40g, 10 pcs/pk
00007-03053WelFlash® SAX, 80g, 10 pcs/pk
00007-03063WelFlash® SAX, 120g, 10 pcs/pk
00007-03075WelFlash® SAX, 220g, 6± pcs/pk
00007-03084WelFlash® SAX, 330g, 4 pcs/pk

If you have any problem or require further information, please contact info@welchmat.com.

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