In most cases with GLC the area under the peak as a % of the total area for all peaks is interpreted as representing the % mass of the compound measured in the mixture. Explain why this is only an approximation.
I've tried to find the answer online but couldn't so can someone help me with this one.
Thank you!
The interpretation of the area under the peak in gas chromatography (GLC) as a percentage of the total area is commonly used as an approximation to estimate the percentage mass of the compound in the mixture. However, it is important to note that this interpretation is only an approximation due to several factors that can affect the accuracy of the results.
Firstly, the accuracy of this approximation depends on the assumption that the response factors for all compounds in the mixture are equal. The response factor represents how a compound responds to the detection method (e.g., how it interacts with the detector). If the response factors vary significantly among compounds, the estimated percentage masses based on peak areas will not accurately reflect the true composition of the mixture.
Secondly, the approximation assumes that the efficiency of the separation is equal for all compounds. In practice, the separation efficiency can vary due to differences in molecular size, volatility, and interactions with the stationary phase. If the separation is not ideal, the peaks may overlap or coelute, leading to inaccurate estimations of compound percentages.
Additionally, there can be variations in the column performance, detector response, and injection volume, which can all affect the accuracy of the estimated percentages.
To improve the accuracy of compound identification and quantification in GLC, additional calibration methods can be employed. This involves creating calibration curves using known standards with known concentrations of the compounds of interest. By comparing the peak areas of the unknown samples to the calibration curves, more accurate quantification can be achieved.
In conclusion, while the interpretation of the area under the peak as a percentage of the total area in GLC can provide a rough estimation of compound percentages, it is important to acknowledge its limitations as an approximation due to factors such as varying response factors, separation efficiency, and instrument variations. Employing additional calibration methods can enhance the accuracy of compound quantification in GLC.