Gas chromatograph GC determination of industrial methanol purity, chemical raw material detection, specialized gas chromatograph

GC-9280Gas chromatograph isPureinstrumentA laboratory specific gas chromatograph developed through dedicated research and development, using7-inch color touch screen control, professional chromatograph UI operation interface design, intuitively reflects the internal temperature values of the injection port, column temperature box, detector, and the values of each detector, as well as the running time. It has a one click cooling function, simple and intuitive operation, and easy to use.

gas chromatographGC determination of industrial methanol purity

methanol Also known as Mu Chun (due to*Obtained from wood dry distillation. A colorless, flammable, and pungent liquid with a melting point of -97.56 ℃, boiling point of 64.7 ℃, relative density of 0.7913, soluble in water and most organic solvents. It is highly toxic and can damage the optic nerve. Improper consumption can cause blindness and even death. At present, in China's industry, methanol is prepared by pressurized heating of carbon monoxide and hydrogen in the presence of a catalyst: if the conditions are strictly controlled, the yield can reach 100% and the purity can reach 99%. Methane can also be mixed with oxygen (9:1, V/V) to produce methanol through a copper tube under heating and pressure conditions. Methanol has the general properties of aliphatic primary alcohols, and all three hydrogen atoms on carbon atoms with hydroxyl groups can be oxidized to gradually produce formaldehyde, formic acid, and ultimately carbon dioxide. Therefore, one important use of methanol is the synthesis of formaldehyde. Methanol can also be easily converted into important organic synthesis intermediates such as methyl carboxylate, chloromethane, and methylamine. Methanol is still an important organic solvent, extractant, and alcohol denaturing agent.

Experimental Section

1、 Reagents and materials

1.1 Methanol: analytical grade; 3.2 Carrier gas (supplementary gas): nitrogen, with a purity greater than 99.99%;

1.2Gas: Hydrogen, with a purity greater than 99.99%; 3.4 Auxiliary gas: Air, thoroughly dried and purified through silica gel and molecular sieve;

1.3Ethanol: analytical grade. 3.6 Fixed phase: GDX-103.

IIInstruments and equipment

2.1 Puregas chromatographThe temperature of the column box can be controlled within± 0.5 ℃, equipped with a thermal conductivity detector, the peak height generated by each component to be tested with a mass fraction not exceeding 0.01% should be greater than twice the noise.

2.2 Sample injector micro injector: 5 μ L;

2.3 Chromatographic Column: Stainless steel column, 3m × Φ 3mm

2.3.1 Packing method of chromatographic column and loading amount of stationary phase

Block the outlet end of the chromatographic column (the end connected to the detector) with a small amount of glass wool and metal mesh, then evacuate from the outlet end and gently tap to load the stationary phase. The amount of stationary phase loaded is1.8g/m。

2.3.2 Aging of chromatographic columns: Aging at 100 ℃ for at least 8 hours before use, and the flow rate of the carrier gas during aging should be the same as that during sample analysis.

2.4 Data Processingworkstation Chromatographic data processing can input the required peak shape parameter correction factor and time program, and can integrate and calculate correctly, meeting the requirements of 4.1.

IIISample sampling shall be conducted in accordance with the provisions of GB6680.

4Operation steps

4.1 Puregas chromatographAfter startup, make necessary adjustments to achieve the following typical analysis conditions:

Column temperature:75 ℃ or the appropriate chromatographic column temperature selected by the user.

Detector temperature:130 ℃ or a suitable detector temperature selected by the user.

Vaporization chamber temperature:130 ℃ or a suitable vaporization chamber temperature selected by the user.

Carrier gas: hydrogen, flow rate45mL/min or a suitable carrier gas flow rate can be selected by the user to achieve better separation efficiency. Injection volume: 2 μ L.

4.2 Sample determination: Use a microsyringe to aspirate 2 μ L of the sample, inject it twice continuously, record the peak area with a data processor, and calculate the content of each component.

4.3 The standard chromatogram is shown in the following figure.

4.4 The relative correction factor and relative retention time are shown in Table 1.

5calculate：Adopt peak area normalization method.

VIExpression of analysis results

For any sample, the analysis result should be expressed as the arithmetic mean of two repeated measurements, rounded to two decimal places.

7、 Repeatability

The same operator uses the same instrument to perform repeated measurements on the same sample under the same conditions using normal and correct operating methods. The difference between the two measurement results shall not exceed0.02%.

8、 Measurement results and discussion

This standard specifies the method for determining the purity of industrial methanol. This standard is applicable to the determination of purity of industrial methanol.

Update time: September 4, 2020 16:48:45