The gas chromatograph should pay attention to the following factors in use:
(1) Environmental conditions The gas chromatograph does not have strict requirements on the ambient temperature. Generally, it can be operated normally at room temperature of 5 ～ 35 ℃. However, the general requirement for the ambient humidity is 20% to 85%. In highly humid areas, when using the hydrogen flame ionization detector of some models, the humidity of the amplifier will cause the amplifier insulated gas chromatograph to pay attention to the following factors in use:
(1) Environmental conditions The gas chromatograph does not have strict requirements on the ambient temperature. Generally, it can be operated normally at room temperature of 5 ～ 35 ℃. However, the general requirement for the ambient humidity is 20% to 85%. In highly humid areas, when using the hydrogen flame ionization detector of some models, the insulation performance of the amplifier will be reduced due to high humidity. If you operate on a high sensitivity block, the response value will decrease. Analysts should take necessary measures if they encounter the above phenomena while using the instrument.
(2) The purity of the gas source used in the gas purity gas chromatograph must be above 99.99%. At present, many operators have not paid enough attention to the problem of different detectors requiring different gas source purity. In use, the detector may have high detection limits and unstable baseline due to insufficient gas source purity. For example, when hydrogen with a purity of 98% is used as the gas source of the hydrogen flame ionization detector, when it is used on the 104MΩ sensitivity block of the detector, the baseline may be seriously unstable due to insufficient hydrogen purity (containing flammable gases such as methane). , As if there are peaks that never end. If the purity of the carrier gas is not high and the trace oxygen is contained, it will affect the life of the capillary column.
(3) Selection of air flow ratio For the lower hydrogen flame ionization detector, N2-H2-Air flame is required, and it should be an oxygen-enriched flame after ignition, that is, the air should be excessive to ensure that the hydrogen is completely burned, the best ratio of the three gases N2: H2 = 1: (0.85 ～ 1), Air: H2 = (6 ～ 8): 1 or greater air volume. Under this condition, the detector has high sensitivity, good stability and reliable quantitative correction factors.
The performance is degraded. If you operate on the high sensitivity gear, the response value will decrease. Analysts should take necessary measures if they encounter the above phenomena while using the instrument.
(2) The purity of the gas source used in the gas purity gas chromatograph must be above 99.99%. At present, many operators have not paid enough attention to the problem of different detectors requiring different gas source purity. In use, the detector may have high detection limits and unstable baseline due to insufficient gas source purity. For example, when hydrogen with a purity of 98% is used as the gas source of the hydrogen flame ionization detector, when it is used on the 104MΩ sensitivity block of the detector, the baseline may be seriously unstable due to insufficient hydrogen purity (containing flammable gases such as methane). , As if there are peaks that never end. If the purity of the carrier gas is not high and the trace oxygen is contained, it will affect the life of the capillary column.
(3) Selection of air flow ratio For the lower hydrogen flame ionization detector, N2-H2-Air flame is required, and it should be an oxygen-enriched flame after ignition, that is, the air should be excessive to ensure that the hydrogen is completely burned, the best ratio of the three gases N2: H2 = 1: (0.85 ～ 1), Air: H2 = (6 ～ 8): 1 or greater air volume. Under this condition, the detector has high sensitivity, good stability and reliable quantitative correction factors.
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