On top of that, the experiment is conducted to explore the gas chromatography, which is include the concepts of retention time and resolution using a mixture of methyl sters: methyl linolate, methyl laurate, methyl myristate, and methylpalmitate and methyl stearate. In this experiment, the isothermal and temperature programming are required In order to get an optimize parameter. The efficient separation of compounds In GC Is dependent on the compounds travelling through the column at different rates.
There are several factors at which a compound travels through a particular GC systems depends on that include column temperature, carrier gas flow rate, length of the column and volatility of a compound. In this context, the increase in column temperature will speeds up the elution time of a compound mixture. Moreover, as the carrier gas flow rate is Increase, the speeds at which all compounds move through the column will also Increase. All these factors are related to the optimization of the gas chromatography in order to have a good resolution.
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Gas chromatography (GC) is a widely used technique in which the mobile phase is a carrier gas, usually helium or nitrogen and the stationary phase is a microscopic layer of liquid or polymer on an inert solid support inside glass or metal tubing. In order for separation to occur, the stationary phase must have an affinity for the analytes In the sample mixture. The mobile phase Is Inert and does not Interact analytes through the length of the column.
Gas chromatography is in principle similar to column chromatography (as well as other forms of chromatography, such as HPLC, TLC), but has several notable differences. Firstly, the process of separating the compounds in a mixture is carried out between a liquid stationary phase and a gas mobile phase, whereas in column chromatography the stationary phase is a solid and the mobile phase is a liquid. (Hence the full name of the procedure is “Gas- liquid chromatography”, referring to the mobile and stationary phases, respectively.
Secondly, the column through which the gas phase passes is located in an oven “here the temperature of the gas can be controlled, whereas column chromatography (typically) has no such temperature control. Thirdly, the concentration of a compound in the gas phase is solely a function of the vapor pressure of the gas. In this experiment we are ask to analyse only 3 compound methyl laurate, methyl myristate, and methyl palmitate by Dr. Fauzi. INSTRUMENTATION Gas Chromatograph (Agilent Technologies 6890N) equipped with flame ionization detector (FID) and 30 m 250 m 0. 5 m HP5-MS capillary column. EXPERIMENTAL PROCEDURE Instrument set up Injection port split (40M) Injection port temperature 250 Oven temperature 210 Column flow rate 30 cm/s Detector temperature Preparation effect of carrier gas flow rate on isothermal GC separation of methyl ester 1) The 0. 4 pm standard solution mixture isothermally was injected at 210 at carrier gas flow rate of 30 cm/s. 2) The flow rate is increased to 50cm/s and 70cm/s. 3) Allow a few minutes for the system to equilibrate and the standard mixture is injected again.
Determine the optimum flowrate. Preparation effect of column temperature on the isothermal GC separation of methyl esters 1) 0. pm of standard mixture isothermally was injected at 170, 190 and 250 at the optimal carrier gas flow and analysis time was eluted. Preparation of separation of methyl esters using column temperature programming 1) The standard was injected at the optimal carrier gas flow rate using a linear temperature ramp was injected from 100 to 290 at 70cm/s.
Isothermal GC separation means that the column temperature used is constant along the separation which is 170, 190, and 210 respectively and we determined the effect of using a constant temperature to the separation. The result shows that the separation is better when using the column temperature of 210 with the flow rate of 70cm/s. This is because compared to other temperature and flow ate, the retention time of the standard to appear in the sample is better using this temperature. This indicates that the sample could separate well and then give the best separation, thus give higher efficiency.
The efficiency is described as the time taken for the peak to separate. This is probably due to the limitation of the standard Nhich means the standard has run out or finish. In any case, if the column is maintained at a low temperature for the duration of a sample run, it will results the first peaks to elute will likely be well-spaced, however the components which staying n the column longer will find themselves bound to the stationary phase for longer elution times. Using higher temperature, these components spend more time in the mobile phase, helping then to elute faster and minimizing the band-broadening.
Somehow, the faster peaks also elute faster however, pressing the peaks so close together which may cause them to not be resolved properly. The carrier gas linear delocity or flow rate is directly influences retention time and efficiency of the column n gas chromatography. In order to obtain the best analysis time and higher fficiency, the proper selection and setting of the carrier gas need to be chosen. It is because, if we wrongly set up the carrier gas flow rate, we could obtain a terrify result of separation.
The carrier gas linear velocity or flow rate is controlled by adjusting the carrier gas pressure at the front of the column which commonly called the head pressure. The pressure setting is dependent on the type of carrier gas, the column length and diameter, column temperature and desired linear velocity or flow rate. There a several precautions that needs to be taken in order to have a good analysis. In this experiment, the sample preparation is very crucial because we want to make sure that there is no water presence in the sample.