Gas Chromatography Lab Report

Gas chromatography is a technique by which mixtures of volatile substances can be separated. Mass spectroscopy is a technique that analyses the mass of volatile molecules and their fragments. By using both techniques together, separated compounds are detected by their mass fragments. In this experiment, the CSUDH Chemistry Department Agilent 6890 N Gas Chromatograph, interfaced with an Agilent 5975B XL Mass Selective Detector was used. With this GC-MS machine, a mixture of compounds can be separated and detected by analyzing the mass spectrum data. This process is possible because several compounds have different chemical and physical properties; therefore, some compounds can linger in the column for different times. These properties include:

This experiment consists of two parts: calibration and assay. For the calibration working standards of methyl paraben were created from stock solutions. The calibration data is used to determine the concentration of analyte in the sample. Since this experiment is qualitative and quantitative analyses of methyl paraben, in the qualitative analysis methyl paraben and propyl paraben are identified from their molar masses using the mass spectrum. In the quantitative analysis of methyl paraben, both methyl and propyl paraben are identified by using the retention time from the chromatogram. There are two parts for the quantitative analysis. In the first part, propyl paraben is added to a sample of methyl paraben as the internal standard and the relative response factor is calculated from the peak areas and the concentration data. In the second part, serial dilutions from five standard solutions of methyl paraben are performed. The absorbance of each standard solution is measured and a absorbance vs. concentration graph is plotted. The linear equation of the graph is obtained to calculate the concentration of an unknown solution. Both parts of quantitative analysis are paired for the t-test