D-Limonene Gas Chromatography
D-limonene is a primary constituent in citrus oils that can be used as an insecticide, a fragrance, a solvent, or possibly a biofuel.1 It is a somewhat non-polar hydrocarbon that can be extracted from orange rinds using a relatively non-polar solvent such as liquid carbon dioxide (CO2) or ethyl acetate. 1
CO2 exists in a gas phase at room temperature and 1 atm, but can also be obtained in solid phase (dry ice) for a general laboratory setting. In order to obtain liquid phase CO2 at room temperature and 1 atm, CO2 has to be pressurized and heated past the triple point, shown in Figure 1. 1 At temperatures above -56.6°C and pressures above 5.1 atm, liquid CO2 can be formed condensed and be used to extract limonene.1 The high pressure could be achieved by increasing the moles of CO2 gas …show more content…
Gas chromatography (GC) is a type of chromatography that uses a carrier gas as the mobile phase and a column as the stationary phase. The sample is injected into the instrument and is heated until the sample, which includes both analyte and solvent, boils. The analyte must have a relatively low boiling point in order to be to be pushed through the column along with the carrier gas, helium.1 The column used in the experiment was a non-polar Agilent HP-5 column (specific phase found in Table 1).1 The separation of analytes is mainly attributed to two factors: the boiling points of the analytes and the polarity of the analytes. Analytes that are more non-polar are attracted to a non-polar column and elute slower than analytes that are more polar. Analytes with lower boiling points would boil first and elute before analytes with higher boiling points. The two factors affect retention time, which is used to determine the identity of eluted compounds. For the experiment, the internal standard anisole was eluted before limonene because it was more polar and had a lower boiling
CO2 exists in a gas phase at room temperature and 1 atm, but can also be obtained in solid phase (dry ice) for a general laboratory setting. In order to obtain liquid phase CO2 at room temperature and 1 atm, CO2 has to be pressurized and heated past the triple point, shown in Figure 1. 1 At temperatures above -56.6°C and pressures above 5.1 atm, liquid CO2 can be formed condensed and be used to extract limonene.1 The high pressure could be achieved by increasing the moles of CO2 gas …show more content…
Gas chromatography (GC) is a type of chromatography that uses a carrier gas as the mobile phase and a column as the stationary phase. The sample is injected into the instrument and is heated until the sample, which includes both analyte and solvent, boils. The analyte must have a relatively low boiling point in order to be to be pushed through the column along with the carrier gas, helium.1 The column used in the experiment was a non-polar Agilent HP-5 column (specific phase found in Table 1).1 The separation of analytes is mainly attributed to two factors: the boiling points of the analytes and the polarity of the analytes. Analytes that are more non-polar are attracted to a non-polar column and elute slower than analytes that are more polar. Analytes with lower boiling points would boil first and elute before analytes with higher boiling points. The two factors affect retention time, which is used to determine the identity of eluted compounds. For the experiment, the internal standard anisole was eluted before limonene because it was more polar and had a lower boiling