Gas Chromatography Lab

1038 Words 5 Pages
Introduction: The main purpose of this experiment was to take the Gas Chromatography/ Mass Spectrum part of the “Analysis of US bills for cocaine using gas chromatography / mass spectrometry” lab and improve upon the gas chromatographic results. This would be done by finding a way to separate the peaks of cocaine and doxepin. The lab done previously showed the use of two different methods to obtain samples of cocaine and doxepin for spiked dollar bills. The two extraction methods were liquid-liquid extraction and solid phase extraction. This lab had some difficulties due to the less than ideal separation the of cocaine and doxepin peaks on chromatograms. The proposed idea was to change the parameters used in the GC/MS instrument to possibly obtain better separation. The part of that lab that would be specifically focused in on is the solid phase extraction. This extraction involves an elution step involving methanol as the solvent. One of the proposed ways to improve the separation of the two chemicals was to increase the volume of methanol used to elute in this step1. …show more content…
Figure’s 3, 5, and 6 had injection temperatures set at 230, 210, and 250 °C respectively. The best retention time separation of the three was the sample with the injection temperature set at 250°C. This was then the injection temperature that would be used for the rest of the data collected. Figure’s 6, 7, 8, 9, and 10 address the optimal elution volume of methanol part of the experiment. Figure’s 6, 7, 8, 9, and 10 had elution volumes of 2 mL, 3 mL, 4 mL, 5 mL, and 6 mL respectively. The best retention time separation of the three was the sample with elution volume of 6 mL. Although it did have the most separation, figure 10 compared to figure 9 shows that an elution volume of 5 mL may have slightly better chromatograms. An elution volume of 5 mL was used for the final part of the experiment due to this

Related Documents