The aim which has been set for this literature is to research an analytical technique used for pharmaceutical analysis and write about the discoveries which were made. As pharmacy students it is vital that we are aware of the techniques used the quality control of pharmaceutical1products, as well understand the theory behind these operations and procedures. The focus of this study will be Mass Spectroscopy and understanding the intricate details involved in its operation. The main objective of this study will to highlight all the main topics pertaining to Mass spectroscopy.
In pharmaceutical analysis different methods are used1in determining various aspects about a sample which is being tested. Analytical procedures provide valuable information relating to the identity of a drug, the identity1of the impurities1in the drug, the1percentage purity of the drug1as well as other1factors which are relevant. There is a wide range of methods that are used for analysis such as different types of chromatography,1visible and1ultra violet sspectroscopy,1infrared spectrophotometry,1atomic spectrophotometry,1molecular1emission spectroscopy, nuclear1magnetic resonance spectroscopy,1mass spectrometry and a variety of other methods. The Mass1spectrometry techniques will be the prime focus of this study.
The quality control testing of drugs is of utmost importance and needs to be performed as accurately as possible. Medicines are marketed1as safe and1therapeutically active1formulations, so quality control instruments are part of the daily operation of pharmaceutical companies. This ensures that the drugs produced act1in the anticipated modus in1order for1patients to achieve their maximum therapeutic outcomes.
This is the primary procedure which is used to quantify the molecular mass of compounds. This method provides valuable information on the structure of a compound. Once a substances mass has been identified, the compound is then easily identifiable. In order to measure a substances weight it needs to be1converted to1a beam of1positively charged1ions in a1gas phase. The sample is1then bombarded with1high energy1electrons in1order to transform them1to positive1ions. The ions are1then divided using a1mass analyser on1the basis of1their charge to1mass ratio, by1making use of1either electric or1magnetic fields.
The mass spectrum can be explained as being a plot of the vast amount of ions which are produced as a result of electron bombardment to their mass to charge ratio. This ratio can be seen as being equivalent to mass due to most ions which are charged is singularly charged. A degree of efficiency of the ions which contain different masses and are separated by the mass spectrometer can be measured which is known as the resolution. Nowadays, there are both high and low resolution instrumentation which is commercially available. It can be seen that a low resolution instrument has the ability of only distinguishing a mass difference between ions of only 1 a.m.u (atomic mass unit). On the other hand, the great advantage of the high resolution instrument can differentiate ions which differ in masses as low as 0.0001 a.m.u (atomic mass units). Currently, we have four types of techniques known to us for usage. They are: chemical & electrospray ionization, electron ionization, fast atom bombardment as well as electron ionization mass spectrometry. In order to analyse the technique of mass spectrometry, it is important to conceptualise various isotopes relative abundance. This will have a major impact on the mass of the sample which is being analysed. It can be seen that isotopes will relay M+1 as well as M+2 peaks. The spectra which are depicted may show the occurrence of chlorine which will then indicate that the ratio of M+1 and M+2 is roughly 3:1.
If it seen that the ratio is 1:1, this will show the occurrence of Bromine. It is known that the most occurring elements to be found showing these peaks are Bromine and Chlorine. Fragmentation is also used. Fragmentation is when a high energy electron usually about 70eV provides sufficient energy to dislodge an electron for the test compound to cause ionisation but also to cause fragmentation by breaking the compound into fragments. When fragmenting a molecular ion, it produces a cation and a radical. Only the cation is detected by mass spectroscopy.
There are a number of applications for mass spectroscopy. It is a highly specific method to determine the identity, structure of drugs and raw materials. It is used to characterise impurities and to determine drugs and their metabolites in biological fluids and tissues, when coupled with gas chromatography or liquid chromatography. Chromatography is a separation technique. It involves a mobile and a stationary phase. It is based on the interaction of the drug with the two phases. The drug or sample being tested is dissolved in the mobile phase and is then forced through the immobile or stationary phase. There are many different types of chromatography for eg. Gas chromatography. After the separation in the mixture of a particular compound, mass spectroscopy is used to detect the separated compounds. The high resolving power of gas chromatography in conjunction with the high sensitivity of mass spectrometry, gives rise to a combination of analytical technique which produces valuable results.
During analysis of a sample the compound is introduced into the instrument source by heating it on a probe. This heating causes the compound to volatilize. When the compound is in the vapour phase the compound or now termed analyte is bombarded with high energy electrons which happen between the filament and the target. Rhenium or tungsten filaments supply the high energy electrons. The analyte is accelerated towards a positive target. Fragmentation occurs due to the fact that the electrons used are of much higher energy than the analytes bonds can handle. Two main types of systems called magnetic sector instruments and quadrupole instruments are used to separate ions on the basis of their charge to mass ratio.
Mass spectrometry is not used in the quality control of medicines as a norm but mainly it is used in conjunction with other methods in research and developments departments. The equipment needed for mass spectrometry is expensive and requires experienced technicians as well as routine services and maintenance programmes in order for the equipment to work efficiently. The services and maintenance of the equipment is also costly.
In mass spectroscopy, the mass and structure of the compound is determined to either identify the compound being analysed or to confirm its identity and purity by comparing the mass obtained to BP standards. To become an expert on drugs, studying the complexities of analytical techniques are important as it is a significant component of the pharmacist's professional field. The objective of this study was therefore achieved
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