Introduction
Chromatographic process is a separation technique which has to do with the mass transfer of test sample between a stationary and mobile phase. HPLC (High Performace Liqud Chromatography) is a vast system which involves the use of a mobile and stationary phase to separate materials. The stationary phase is usually a column packed with solids (usually silica gel) while the mobile phase is usually a solvent or a mixture of various solvents. The mobile phase usually, is the carrier of test sample which has to be completely soluble/dissolved in the mobile phase. This mixture is then made to flow through the chromatographic column (stationary phase) under high pressure where the mixture separates into its various components and subsequently …show more content…
The tablet was dissolved in 100ml of mobile phase (H2O: ACN, 90:10) using a 100ml volumetric flask. This mixture was placed on a sonicate bath for 15 minutes to allow for complete dissolution of the aspirin. Using a syringe driven filter device, the solution was filtered to get rid of the insoluble excipients like talc contained in the aspirin tablet. A pipette was used to transfer 0.2ml of the stock solution into six (6) different 10ml volumetric flasks. The volumetric flasks were labelled 1 to 6 accordingly.
Standard Aspirin preparation: 100mg of standard aspirin crystals was weighed carefully using a weighing balance. The aspirin crystals was transferred into a 100ml volumetric flask and dissolved in 100ml of mobile phase. The solution was mixed properly by agitation to ensure a complete dissolution. Using this solution, a spike was produced by standard addition of different volumes into each of the six (6) volumetric flasks containing 0.2ml each of the unknown sample. Five pipettes were set at different volumetric capacities of 0.2ml, 0.4ml, 0.6ml, 0.8ml and 1.0ml. No amount of spike solution was added to volumetric flask number 1, then 0.2ml, 0.4ml, 0.6ml, 0.8ml and 1.0ml were added to volumetric flasks labelled 2, 3, 4, 5 and 6 respectively. The resulting solutions were made up to 10ml each with mobile phase. Subsequently, 2ml of …show more content…
From fig 2.2, it can be seen that the linear residuals are relatively far from the base line which is an indication of non-proportionality in the system. The standard error of this process is 2342 and correlation coefficient R2 is 0.8651 which is an unacceptable correlation(Fogel et al. 1984). However, when the 4th and 5th points on the linear residuals are arbitrarily removed, standard error reduces to 1877 and a better value of R2=0.9027 is obtained. Also, a more realistic concentration of aspirin (291.16mg) was obtained with confidence level of ±1253mg.
In this experiment, some levels of procedural irregularity was recorded in area under peak for the six spiked solutions as seen in fig 2.0. According to Beer-lambert law, absorbance is directly proportional to concentration. Hence, area under peak is related to concentration of the solutions. From the graphical expression in fig 2.1, it can be deduced that there is no correlation between the signal strength (peak area) and volume of standard aspirin solution added. This irregularity was brought about by a consequential alteration of the concentration of final solution for HPLC analysis. This error occurred as a result of the use of the same syringe which was used to transfer all the different spiked solutions into the HPLC auto sampling vails prior
Chromatographic process is a separation technique which has to do with the mass transfer of test sample between a stationary and mobile phase. HPLC (High Performace Liqud Chromatography) is a vast system which involves the use of a mobile and stationary phase to separate materials. The stationary phase is usually a column packed with solids (usually silica gel) while the mobile phase is usually a solvent or a mixture of various solvents. The mobile phase usually, is the carrier of test sample which has to be completely soluble/dissolved in the mobile phase. This mixture is then made to flow through the chromatographic column (stationary phase) under high pressure where the mixture separates into its various components and subsequently …show more content…
The tablet was dissolved in 100ml of mobile phase (H2O: ACN, 90:10) using a 100ml volumetric flask. This mixture was placed on a sonicate bath for 15 minutes to allow for complete dissolution of the aspirin. Using a syringe driven filter device, the solution was filtered to get rid of the insoluble excipients like talc contained in the aspirin tablet. A pipette was used to transfer 0.2ml of the stock solution into six (6) different 10ml volumetric flasks. The volumetric flasks were labelled 1 to 6 accordingly.
Standard Aspirin preparation: 100mg of standard aspirin crystals was weighed carefully using a weighing balance. The aspirin crystals was transferred into a 100ml volumetric flask and dissolved in 100ml of mobile phase. The solution was mixed properly by agitation to ensure a complete dissolution. Using this solution, a spike was produced by standard addition of different volumes into each of the six (6) volumetric flasks containing 0.2ml each of the unknown sample. Five pipettes were set at different volumetric capacities of 0.2ml, 0.4ml, 0.6ml, 0.8ml and 1.0ml. No amount of spike solution was added to volumetric flask number 1, then 0.2ml, 0.4ml, 0.6ml, 0.8ml and 1.0ml were added to volumetric flasks labelled 2, 3, 4, 5 and 6 respectively. The resulting solutions were made up to 10ml each with mobile phase. Subsequently, 2ml of …show more content…
From fig 2.2, it can be seen that the linear residuals are relatively far from the base line which is an indication of non-proportionality in the system. The standard error of this process is 2342 and correlation coefficient R2 is 0.8651 which is an unacceptable correlation(Fogel et al. 1984). However, when the 4th and 5th points on the linear residuals are arbitrarily removed, standard error reduces to 1877 and a better value of R2=0.9027 is obtained. Also, a more realistic concentration of aspirin (291.16mg) was obtained with confidence level of ±1253mg.
In this experiment, some levels of procedural irregularity was recorded in area under peak for the six spiked solutions as seen in fig 2.0. According to Beer-lambert law, absorbance is directly proportional to concentration. Hence, area under peak is related to concentration of the solutions. From the graphical expression in fig 2.1, it can be deduced that there is no correlation between the signal strength (peak area) and volume of standard aspirin solution added. This irregularity was brought about by a consequential alteration of the concentration of final solution for HPLC analysis. This error occurred as a result of the use of the same syringe which was used to transfer all the different spiked solutions into the HPLC auto sampling vails prior