Monday, October 22, 2018

Principle of column chromatography

The column chromatography is a broadly used technique for the separation or purification of the sample components. Solute adsorption of solution through a stationary phase and separates the mixture into each analyte, it depends on the affinity between the mobile phase and the stationary phase. The molecules which are less affinity towards the stationary phase early separated and molecules have more affinity which separated later. The mobile phase and stationary phase are the two phases of column chromatography in which the mobile phase is liquid and solid stationary phase is used. The sample mixture travels through the stationary phase with the mobile phase and separates the sample based on the affinity of each component toward the silica. The wet and dry method used for the preparation of the column.
Dry method:
In the dry method, the column is filled with the dry silica, and the mobile phase passes through it till silica is properly wet and settled. In this method of column chromatography, the column should always wet with the solvent until the end of the work.
Wet method:
In the wet method slurry of silica and solvent is first made and then using a funnel is inserted on the column it also needs to settle and wet until the end.
In some applications, different types of column chromatography such as adsorption chromatography, ion-exchange chromatography, partition chromatography, and gel chromatography are used, and they operate under the same principle of column chromatography (adsorption).


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What is Column Chromatography
Pharmaceutical Applications of Column Chromatography
Factors Affecting Separation in Column Chromatography
Different types of Column Chromatography
Advantages and Disadvantages of Column Chromatography
Definition of Partition column chromatography
Basic Principle of Thin Layer Chromatography
What is the basic principle of HPTLC
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Saturday, October 20, 2018

Degradation Kinetics of Drugs in Pharmaceutical Substances

The pharmaceuticals degradation reactions occur in the chemical in nature and at limited rates. Temperature, Solvent, radiation energy, pH of the medium, the presence of a catalyst, and the concentration of reactants are the factors which are having an effect on these reactions. The sequence of reaction is the attribute in the way in which rate of reaction depends on reactant concentration. To make certainly enhanced stability prophecy, it is significant to recognize the limitations of experimental heat obtained by activation values are critical. To calculate the degradation rates at each pH value for dissimilar temperatures, the heat of activation should be obtained for all the bimolecular rate constants concerned in the rate pH profile.
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Pharmaceutical Impurities Arise During Storage

Many impurities may arise during shipment or shelf life of drug products. Therefore, to perform the stability studies are important to evaluate, predict, and make sure the product safety. Stability in sample package, stability in the marketing package, the stability of the formulation, and stability in delivery package, These are all considered for the stability of the drug product and it is significant to make sure that each has to know the significance of stability studies. The impurity related to the fall is to determine how many potential impurities are actually formed in the process of manufacturing and which is under the storage conditions. Throughout the development stage, this information can be utilized to process to modify in an attempt to reduce the impurities. Also, the stability characteristics information can be utilized for packaging, storage and environmental conditions of drug substance so that unacceptable degradation can be reduced or eliminated.

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Formulations Related Impurities in Pharmaceutical Substances

Several impurities in the drug product can be produced since the excipients utilize in a drug substance formulation. In addition, there are different conditions in the formulation process of passing through a drug substance, which can cause its degradation or other unwanted reactions. Due to hydrolysis or solvolysis, the suspensions and solutions are prone to degradation. 
The same reactions can also occur in the solid dosage form in case of capsules and tablets, as solvent or water is used in the process of granulation. The water utilized in the formulation can not only contribute to its impurities, although can also give an ideal condition for the metal catalyst and hydrolysis. Comparative reactions can be visualized in other solvents which can be used, if there is no caution, then oxidation is fairly possible for oxidizing materials. Similarly, light-sensitive material can maintain photochemical reactions. The mainly reactive impurities are small molecules. In addition to chemical stability, the drug products impurity can cause troubles of performance in the form of toxicity or dosage. It is regularly important to quantitatively determine the level of significant impurities from the drug products and to find the origin of those impurities in their source by using the analytical method.
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Synthetic Intermediates and By-Products Impurities in Pharmaceutical Substances

Pharmaceutical compounds Impurity can be produced from raw materials during the synthetic process, by-products, or intermediates. Purity requirements than a drug substance the raw materials are usually produced to lesser purity. So, it's simple to recognize why they can comprise many number components which in turn may affect the purity of the drug substance. Solvents utilize in synthesis are probable to contain many impurities which can increase significant amounts of trace levels, which can react with different chemicals utilize in synthesis, to increase further impurities.
The last intermediate in the synthesis of pharmaceutical is usually necessary to complete certainly predetermined specifications. Though, the additional requires standards of purity for drug substance is used very rarely in this phase, for analysis, this stage the method should be rigid and economically tighter.
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Residual Solvent Impurities in Pharmaceutical Substances

In the drug products normally water is present. As a result, the most volatile impurity, so far in drug products is water, and a lot of time it does not count as the impurity. It is common in the excipients and drug substances and is utilized in the preparation of dose form too. The content of moisture can be significant as packaged in the dosage form, like there is no equilibration with the environment, under this environment, the moisture brings into the system via excipients may be sufficient to for hydrolysis. In adding, Water from the atmosphere can influence drug products and can often be harmful to their dosage performance or chemical stability. The chemical stability issues linking with water are for the most part caused by hydrolysis, especially carboxylic acid derivatives and other sensitive functionalities. For several drugs, the level of moisture will determine whether a hydrate can generate. In several cases, the formation of the hydrate can cause a loss in crystalline, this, in turn, could get extra chemical instability of the drug.
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Stereochemistry Related Impurities in Pharmaceutical Substances

It is most important to see compounds related to stereochemistry, these compounds have the same chemical structure, but there is a different spatial orientation. These types of compounds can be considered as impurities in the active pharmaceutical ingredients. The chirality can be observed in a molecule containing one or more tetrahedral carbon by four dissimilar substances. Chiral molecules can also be due to many different reasons and should be the factor in any impurities evaluation. Chiral molecules are often called enantiomers. The enantiomers optical isomers with similar chemical structure, but are the dissimilar spatial arrangement.

It is important that they do not ignore them because a compound d-isomer may have dissimilar toxicological or pharmacological activity, so, the unwanted optical isomer is considered to be active pharmaceutical ingredients chiral impurity. Also, it is significant to consider that the number of chiral impurities increases with the rising number of asymmetric carbon atoms in the molecule.


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Residual Solvent Impurities in Pharmaceutical Substances
Synthetic Intermediates and By-Products Impurities in Pharmaceutical Substances
Formulations Related Impurities in Pharmaceutical Substances
Pharmaceutical Impurities Arise During Storage
Degradation Kinetics of Drugs in Pharmaceutical Substances
Definition of Impurity in Pharmaceuticals
Isolation and Characterization of Impurities in Pharmaceuticals
Sources of Impurities in Pharmaceuticals
Different Types of Impurities in Pharmaceutical Substances
Crystallization-Related Impurities in Pharmaceutical Substances
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Crystallization-Related Impurities in Pharmaceutical Substances

Polymorphism is used to indicate the crystal system where a substance can be present in the arrangements of the different crystal packing system, in which all have the similar elemental composition. Probably to contain crystal system, where the substance is present in various crystal packing systems and in which dissimilar elemental composition.
Generally, this goal is in Pharmaceutical manufacturing to manufacture the drug substance which is phase-pure and remains in that condition until the bulk material is stored. One more objective, the drug is to prepare the substance in such a way that it remains in the same phase-pure state throughout the drug product manufacture.
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Different Types of Impurities in Pharmaceutical Substances

A drug or excipients are the source of Impurities in Drug products and also from the packaging and process steps impurities are come. However, many impurities can be identified in any drug product sample; there are fewer impurities which have the effect on performance or stability in the dosage form, in common mainly harmful impurities are small molecules, especially in the solid dose where inadequate mobility prevents reactions of large molecules. 
For the majority of drugs, reactive species have water, metals, and peroxides; these are the impurities that effect on the dosage forms throughout physical changes and chemical reactions in the system. The drug substance purity depends on reducing the level of impurity, not just for release; it should be maintained lower levels throughout the shelf life of the drug substance.
Impurities can be classified into the following categories when the drug substance is chemically synthesized.

  • Organic impurities 
  • Inorganic impurities 
  • Residual solvents 
  • Foreign Substances and other Impurities
  • Toxic Impurities
  • Ordinary Impurities
Therefore, it is necessary to evaluate the impurities using different instruments and techniques, before allocating the purity value to the drug substance.
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Sources of Impurities in Pharmaceuticals

Impurities can arise from different sources, but synthesis is the clearest source of impurities. Where by-products and intermediates can be taken as an impurity in the active pharmaceutical ingredients or they can result in the source of other impurities, every impurity in the initial material is likely to be the active ingredient of interest. Impurities which are associated with solvents and excipients used throughout synthesis should also be considered. Impurities can be produced during various pharmaceutical product manufacturing phases. During different drug product formulation steps, Impurities can be produced. These impurities are likely to be there in the final drug product.
The impurities attributed inert ingredients or drug substance used in the formulation of the drug product, They can express to the drug product during packaging or the formulation process of the different impurities, which is found in the drug product and they are comparatively few who can influence the performance or stability of the dosage form. These impurities cannot affect the stability or performance of the dosage form, however, should be controlled to produce a secure drug product.

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Isolation and Characterization of Impurities in Pharmaceuticals

Impurities are generally considered to be less than active pharmaceutical ingredients, as they may not have the similar level of pharmacological activity as per the active pharmaceutical ingredients. But, it is not always necessary to be less than active pharmaceutical ingredients. From its use point of view, In the case of purity, the drug substance is compromised, even if there is the additional material with better pharmacological properties. We should evaluate the purity of unrelated material; therefore, some external material there in active pharmaceutical ingredients or drug substance should be considered an impurity, even if it is completely inert or has good pharmacological properties So that its material can be properly evaluated in the drug product. Managing the impurities of the lower level is very important as the drug is taken in huge amounts.
It is significant to separate and characterize degradation products and the number of impurities since it is not all the time possible to characterize unambiguously with generally used hyphenated methods, which is often the first line of defense. These methods use detectors such as the mass spectrometer, diode array UV detector, high-performance liquid chromatography, and capillary electrophoresis, etc. and many others are very useful and can reduce the time required to characterize impurities.
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Definition of Impurity in Pharmaceuticals

The definition for impurities is anything that is impure or makes anything also impure. Due to the apparent negativity associated with this word, there was no exact definition of impurity in the pharmaceutical. Impurities can simply define; an impurity is a material that is affecting the purity of drug product/materials, such as drug substance or drug product.
An impurity is usually considered as a drug substance or an active pharmaceutical ingredient excluding organic matter that is produced from the synthesis. Many times Inorganic contaminants are not adequately considered as impurity unless they are toxic.


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Friday, October 19, 2018

Factors Affecting Paper Chromatography

Paper chromatography is an economical but the potent analytical technique of separation of components of complex mixtures that involve very little amounts of material. In this technique involves applying a sample solution as a spot close to one corner of the filter paper and mobile phase runs throughout the paper and as per the affinity of analytes to the mobile phase samples can be separated.
Here are some factors that affect paper chromatography, let’s check it.
Quality of paper used: Some papers are better absorbed and retained than the others. Have to try with the different types and brands of paper. 
Length of the paper: Usually, separation will be better on long paper. 
Type of Solvent used: The solubility of each compound have different, so for different effects of separation try the different solvent. 
The thickness of the paper: Paper thickness is difficult to travel the spot upwards. 
The concentration of the sample or spot: the concentrated spot cannot separate properly and if the very diluted so It cannot be seen properly. 
Effect of Temperature: Temperature can affect the separation of analytes. 


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What is the principle of paper chromatography

The principle of paper chromatography involves "partition" in which compounds are distributed or partitioned between liquid phases.

The paper chromatography technique is parallel to the thin-layer chromatography. Paper chromatography has to be a very successful technique of separation, especially in the analysis of lipid samples and chemical compounds. In paper chromatography, a special type of chromatography paper or a piece of filter paper used as a stationary phase, which is made up with cellulose, sample mixture applied in this paper and paper edge is immersed in a solvent and by capillary action, solvents move up hence the separation of analytes happens.
The principle of paper chromatography involved is the partition in which the components are partitioned or distributed among the liquid phases. The two phases contain water in the pores of the paper and the other phase is a solvent system that travels through the paper. The molecules are separated into the mixture due to the differences in their respective affinity to water and mobile phase throughout the moving of the mobile phase. It also as adsorption chromatography among liquid and solid phases, in which the stationary phase is the solid surface and the mobile phase is the liquid. Although the most commonly used paper chromatography works on the principle of partition chromatography.
There are four different types of paper chromatography such as.
Ascending chromatography: in which the solvent flows by capillary action.
Descending chromatography: in which the mobile phase travels by gravitational force.
Ascending-descending chromatography: in which the solvent moves both upward and downward of the stationary phase,
Horizontal or circular chromatography: in which the sample is applied in the center of a round paper.
Two-dimensional chromatography: this applies to components that have the same Rf values.


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Tuesday, October 16, 2018

What are the advantages of TLC over HPLC chromatography

Thin-layer chromatography (TLC) is used for the separation and quantification of analytes in the form of a mixture of components in the mobile phase. Nowadays, the HPLC chromatography technique is broadly used for quantification and separation of the components. TLC as an important and broadly used separation technique as of its complementary features to the HPLC technique. Most TLC applications for the separation apply normal phase methods, while HPLC has reversed-phase methods dominated.
Compared to HPLC, some of the important features of TLC are mentioned here.
• Simple sample preparation
Sample preparation in TLC is simple as compared to HPLC chromatography. Because each sample is separated on a freshly prepared stationary phase TLC required minimum cleaning steps, not including cross-contaminated. Even, solid particles or firmly absorbed impurities in the sample are also not of much concern. This will be a disaster in HPLC separation, decay, leading to column buildup, and ultimately destroying the performance of the column.
• Separate a large number of components
It is perfect to separate the mixture with a large number of components, Apart from this; it is helpful to verify the purity of the components, although hyphenated HPLC can work as several separation techniques.
• The open set-up of the stationary phase and analysis of the whole sample
The mixture is applied in the stationary phase after development, and this is an open system for the separation to the detection of analytes as compare to TLC, HPLC column is a closed system in which a mixture of sample component is brought into the mobile phase and solutes are eluted and detects at different time intervals as per their polarity. There are times when TLC discloses new and unforeseen information regarding the analytes, while the information in HPLC has been lost by retention at the column, as there is early detection or elution of components and impurities, as well, TLC has less contamination with a stationary phase which is disposable, whereas the column is repeatedly used in HPLC.
• High sample throughput
TLC contains high sample throughput and less time consuming with low cost as well as independent applications and separation, along with many samples. HPLC does not compete with the TLC in the context of the many sample analyses in a given period of time. 
• General and specific detection methods
In TLC, Detection of analytes under the short and long-wave UV light even non-chromophores drug can be possible on a developed TLC plate, but traditional and regular HPLCs still use UV detectors; this detector cannot detect all the eluents from the column separation.
• Flexible and versatile dissolving mobile phase and solvent
The selection of the sample solvent is not equally important in TLC to compare to HPLC, as it is removed by evaporation before the development of the plate. In contrast, the selected dissolving solvent in HPLC should be compatible with the mobile phase and column. The same reason is relevant to the mobile phase of TLC, which is fully evaporated before the detection.


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Factors Affecting Separation in Column Chromatography

Column chromatography is most commonly used, basic and oldest mode of separation of solids and liquids in the form of a complex mixture and separates the compounds on the basis of their polarity. Separation in the column chromatography is significant for efficiency.

Here is mentioned the factors which are affecting the column efficiency.

The dimension of the column:

The ideal length: diameter ratio is 30: 1 or 20: 1, but to improve in efficiency 100: 1 can be additionally suitable.

The particle size of the adsorbent:

The activity of adsorbent reliable on the adsorbent surface area, to increase surface area, Particle size can be reduced and therefore the activity of the adsorbent is increased.

Nature of the solvent:

The solvent flow rate is having an effect of its viscosity. Therefore, the solution has less viscosity are enhanced efficient than a more viscous solvent.

The temperature of the column:

At high temperatures the elution speed of the solvent is increased, usually for all samples separated, at room temperature, if samples are difficult, then the higher temperature can be used.

Pressure:

High pressure on the column and low pressure under the column, it enhances the efficiency of separation.


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What is column chromatography?

Column chromatography is one of the most significant methods of separating, testing the purity of organic compounds, and purifying solids and liquids. It is often used on a small scale or large scale. This is the most significant technique in chemistry in terms of the identification and characterization of the complex mixture of the components. In column chromatography, Adsorbent is a stationary phase, which is either silica gel or alumina and fills in the glass column. Adsorbent, which is used as a stationary phase in column chromatography, is polar, for the separation, an eluent is used, Eluent is a solvent or a mobile phase which is passed through the column. The separation of the sample depends on the polarity of the component since polar compounds do not travel rapidly through the column. This means that polar compounds adsorb more strongly to alumina or silica gel than less polar. The less polar spends more time in the solvent and therefore rinses through the column very fast.
Principle of column chromatography: The sample mixture is dissolved in the mobile phase and introduced over the column. The components are travel and separated according to the affinity towards the stationary phase.
Different types of column chromatography: Adsorption column chromatography, ion-exchange column chromatography, partition column chromatography, gel column chromatography are the types of column chromatography.
Applications of column chromatography: Isolation and purification of alkaloids, vitamins, glycosides, pharmaceuticals, hormones, and other active constituents. 

 
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Advantages and Disadvantages of Column Chromatography

Column chromatography is a general technique that is used to separate the compounds from the complex mixtures. It can use small or large-scale column chromatography to separate and purify the analytes. Column chromatography has two phases, a mobile phase (liquid) and a stationary phase (solid). The sample mixture of compounds travels with the mobile phase through the stationary phase and basis of different degrees of adhesion it separates.The column chromatography works on the principle of adsorption. There are four different column chromatography types for several applications and that work on different mechanisms.

Advantages of column chromatography:
  • Using column chromatography all kinds of complex mixtures can be separated.
  • Any amount of mixture can be separated by column chromatography.
  • A broad range of mobile phases.
  • Analytes can be separated and reused, in preparative type chromatography.
  • It can be possible to run automation.
  • This is a robust method.
Disadvantages of column chromatography:
  • It takes more time to separate the compounds.
  • Column chromatography has of low separation power relative to advanced separation techniques.
  • Higher quantities of solvents are essential, which is more expensive.
  • Automation makes more complex and costly.


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Definition of partition column chromatography

Column partition chromatography is not widely used technology like column chromatography, but all techniques and requirements are similar to column chromatography. This chromatography technique is parallel to the adsorption column chromatography, excluding that the stationary phase is liquid. The silica gel or cellulose is used as a solid support to grasp the stationary phase (liquid) like aqueous buffer solutions or water as on the surface like a thin film. In this type of chromatography mobile phase is parallel to the column chromatography; however, in this technique gradient elution is not used, since the equilibrium will be upset.
Column chromatography is used to isolate solids and liquids from the mixture of the sample solution. There are many applications of column chromatography, one of the major applications is to separate analytes into individual components. The adsorption is the basic principle of column chromatography in which the solutes are separated by using its polarity. Different types of column chromatography are used for separation such as partition chromatography, ion-exchange chromatography, gel chromatography, and adsorption chromatography. This classification of column chromatography based on the mechanism of separation.


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What is Column Chromatography
Pharmaceutical Applications of Column Chromatography
Factors Affecting Separation in Column Chromatography
Advantages and Disadvantages of Column Chromatography
Different types of Column Chromatography
Difference between gas chromatography and liquid chromatography
What are the Advantages of HPLC over GC
Advantages and disadvantages of paper chromatography
Advantages of TLC over Paper Chromatography
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