Category Archives: Chromatography

Application of column chromatography in pharmacy

APPLICATION OF COLUMN CHROMATOGRAPHY IN PHARMACY

January 5, 2018


APPLICATION OF COLUMN CHROMATOGRAPHY IN PHARMACY

Analytical Separation and isolation of chemical compound from a mixture is called as Chromatography and purification of such compounds in larger quantities is achieved prominently using Column Chromatography. Column Chromatography is a separation Technique which is applied in various fields among which Pharmacy is the one, where preparation and dispensing of drugs is performed based on this technique, to ensure the effectiveness of the drug.In Column Chromatography, there are different types of columns such as Gravity Columns, Flash Columns, Low and Medium pressure Columns, Vacuum Columns and High-Pressure Columns. But the similar point in all these columns is that all require an Absorbent, which acts as a Stationary Phase through which sample containing different compounds flow down at differing rates. On the Other hand, the Adsorbent is applied to the Column in 2 ways namely-Slurry packing method and Dry packing Method. Slurry packing method is often used for macro scale separations and Dry packing method for microscale separations.

silica gel for column chromatography mesh size

Silica gel for Column Chromatography

Silica gel is often used for macro scale separations using Slurry pack method where the adsorbent is mixed with a small amount of Non-polar solvent until a consistent paste is formed and then poured in the column.  In dry pack method, a steady stream of the absorbent is poured through a funnel into the column by tapping the sides of the column so that packing remains even in the column. Silica gel for Column Chromatography is considered as the best absorbent in column packing for both dry pack and Slurry pack method, as it gets eventually distributed and forms a packed Stationary phase. The sample is then mixed with a polar solvent and added to the column where the component molecules which are to be separated are either adsorbed on the particle surface or adsorbed into the particle pores. Thus, the different components of a sample get split into separate bands in the column and get eluted at different rates.

Application of column chromatography in pharmacy

The elution is at different rates because of the particle size and pores of Silica gel absorbent which are available in different sizes called as Silica Gel mesh with small size and more pores which act as a Sieve. These Silica gel mesh sizes chromatography is typically used in Column as it retains the compounds for a longer time thereby enhancing the purification of the product. Silica gel for Column chromatography mesh size refers to the number of holes present in the mesh, per unit area of the absorbent to be used in the Column. Silica Gel 100, 200 mesh Merck are employed in Gravity Columns, whereas higher mesh Merck is used in Flash Columns.

Gravity Columns are mainly preferred in Gel Permeation Chromatography and are followed by Adsorption chromatography technique containing Silica gel 100-200 mesh adsorbent gives the higher efficiency of separations, improved reproducibility and require low solvent consumption. Whereas, Flash Columns containing Silica gel (250-400 mesh)  with small particle size, restricts the flow of solvent, therefore pressurized gas is applied to drive the solvent resulting in high resolution.The amount of Silica gel to be used for these Columns mainly depends on the amount of the sample. It means nearly 30 to 100 grams of Silica gel is required for easy separations but for difficult separations more than 30:1 ratio of silica gel is required. With the increase in the quantity of Silica gel, the time consumption for the separation also increases.

 Column chromatography applications

Purification of reaction mixture in chemical synthesis such as

  • Through Flash column chromatography using Silica gel 60(220-240 mesh), β-Ketoester and Desired alcohol were purified,
  • Purification of Polychlorinated biphenyls (PCB) from traces of sulphur using Silica gel 60(70-230 mesh) and Silver nitrate impregnated silica gel.
  • Silica gel (100-200 mesh) for Organ chlorine Pesticides, Phenols and Polynuclear aromatic compounds

Purification of biomolecules such as proteins for pharmaceutical research

  • Synthesis of Pramlintide which is an analogue of Amylin, a peptide hormone, for treating type 1 and type 2 Diabetics is also purified using Silica gel.
  • Purification of bioactive glycolipids, showing antiviral activity towards HSV-1(Herpes Virus)is also performed by Column chromatography using Silica gel as absorbent.
  • Purification of Nucleic acids in vivo and vitro cultures is also done using Silica gel as it absorbs the Nucleic acid.

Analysis of environmental samples

  • Purification of target chemical from co-extracted, non-chemical samples from the environment is done using Gas chromatography, in which the environmental samples are passed through an inert gas where the target chemical gets desorbed from aqueous phase to gas phase and gets separated from a stream of gas by absorption on the Silica gel mesh. On heating it the trapped chemical get released and can be analyzed
  • Extraction of pesticides from solid food samples of animal origin containing lipids, waxes and pigments as contaminants are performed using Silica gel adsorption chromatography in atmospheric condition.

 

RANGE OF SILICA GEL MESH FOR CHROMOTOGRAPHY

September 11, 2017


Discovery of Chromatography technique has made a revolution in the field of analytical laboratories for the separation of the chemicals after synthesis. Since the separation process for each compound is different based on their physical interactions with the solute and the absorbent, different methods were discovered for an efficient and reliable analysis. Since for any chromatographic technique, the absorbent remains the same i.e. Silica Gel adsorbent, because it is low acidic and available in definite particle size ranging from 60-800 mesh size. There are many Chromatography techniques theoretically, but only few can be operated practically in the laboratories. Among these techniques Column chromatographic techniques are mostly preferred as it is low in cost as well as requires minimum instrumentation. In turn based on the flow of the solvent down the column through the absorbent, Column chromatography is classified into Gravity Column Chromatography and Flash Chromatography. The flow of the solvent in the column is based on the definite pore size of the Silica Gel, which allows smaller molecules into its matrix and thereby excludes the larger molecules which flow down and get eluted faster.

 

Silica Gel Mesh for Chromatography

If the solvent flows down the column passing the Silica gel absorbent of definite particle size by gravity or fissure, it is referred to as Gravity Column Chromatography. But if the solvent flows down the column passing the Silica gel absorbent of definite particle size by positive air pressure, it is referred to as Flash Chromatography. Therefore the absorbent used in both these techniques is the same, the Silica Gel Mesh. There are many products of Silica Gel mesh available depending on the mesh size such as Silica Gel 60-120 mesh, Silica Gel 60-200 mesh, Silica Gel 70-230 mesh, Silica Gel 200-400 mesh and Silica Gel 400-800 mesh. Among this Silica Gel 70-230 mesh is used for Gravity Column Chromatography and Silica Gel 200-400 mesh is used in Flash Chromatography. These all are available in a thin white free flowing powder form with a density of 0.75 gm per ml. Best separation is achieved in Ordinary compounds by Silica Gel Absorbent. Apart from Gravity Column Chromatography and Flash Chromatography, there is another technique in Chromatography named as Reversed-phase Chromatography, which is employed for the solvent which is more polar than the Absorbent. Silica gel was the first polymer used formerly in Reversed-phase Chromatography for the purification of small organic molecules but later for the purification of synthesized Peptides. The separation is achieved by the partitioning mechanism between the Stationary phase and the mobile phase in Reversed-phase Chromatography, in which the stationary phase is Silica Gel.

 

Overall, in each and every Chromatographic techniques the main absorbent is the Silica gel and is considered as the best absorbent in the analytical field, as it is porous, insoluble and its hydrophobic interaction with the solvent makes the elution process progress at a faster rate as the polar components get eluted first. These Silica gels exist in different particle sizes, because of which they are used in many Column Chromatography Techniques and Sorbead being the best Silica gel 200-400 supplier and Silica gel 70-230 mesh supplier.

Use of Silica Gel in Flash Chromatography

Use of Silica Gel in Flash Chromatography

January 28, 2017


Flash Chromatography – An Introduction

Flash chromatography is also known as “medium pressure chromatography”. This form of chromatography works by air pressure driving the mixture, which is to be separated down the vertical glass column. This type of chromatography is ideal for separations that need to take place in a fast paced manner.

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thin layer chromatography

Silica Gel Desiccants in Thin Layer Chromatography

September 27, 2016


Understanding Thin layer Chromatography

Thin layer chromatography is a widely used form of chromatography. This type of chromatography mainly finds use in the separation process of non-volatile mixtures. Thin-layer chromatography consists of both a stationary phase as well as a mobile phase. The stationary phase is usually an adsorbent like Silica Gel, Aluminium Oxide or Cellulose. The thin-layer chromatography process works by the molecular adsorbent like Silica Gel absorbing the different components of the mixture, which has to be separated, at different levels. The adsorbents for thin-layer chromatography are always decided in such a manner that they will quicken as well as improve the separation as well as the subsequent purification process.

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