Gas chromatograph

The measurement is related to the sample and the column, right? It has nothing to do with the model of the chromatograph, right?

Basic Knowledge of Gas Chromatography I. A Brief Introduction to Gas Chromatography Gas chromatography is a significant scientific and technological achievement that emerged in the 1950s. It is a new separation and analysis technique that is widely used in industry, agriculture, national defense, construction, and scientific research. Gas chromatography can be divided into gas-solid chromatography and gas-liquid chromatography. In gas-solid chromatography, the term “gas” refers to the mobile phase being a gas, while the term “solid” refers to the solid material of the stationary phase. Such as activated carbon, silica gel, etc. In gas-liquid chromatography, the “gas” refers to the mobile phase being a gas, while the “liquid” refers to the stationary phase being a liquid. For example, by coating diatomaceous earth, an inert material, with squalane, it is possible to separate and determine trace impurities such as methane, acetylene, propylene, propane, etc. in pure ethylene. 　　II. Characteristics of gas chromatography Gas chromatography is a type of chromatography that uses gas as the mobile phase. Due to the fast transfer rate of the sample in the gas phase, the sample components can reach equilibrium between the mobile phase and the stationary phase instantaneously. In addition, there are many substances that can be used as the stationary phase, so gas chromatography is a separation and analysis method with fast analysis speed and high separation efficiency. In recent years, the use of highly sensitive and selective detectors has endowed it with advantages such as high analytical sensitivity and a wide range of applications. 　　III. Applications of Gas Chromatography In the petrochemical industry, gas chromatography can be used to analyze most raw materials and products ； It can be used in the power sector to detect latent faults in transformers ； It can be used to monitor the quality of urban air and water in environmental protection efforts ； It can be used in agriculture to monitor residual pesticides in crops ； In the commercial sector, it can be used to examine and assess the quality of food ； It can be used in medicine to study human metabolism and physiological functions ； It is used clinically to distinguish between drug poisoning and different types of diseases ； In cosmic vessels, it can be used to automatically monitor the gases inside the ship’s sealed compartments, among other things. 　　Gas Chromatography Knowledge 　　1 Gas Chromatography 　　Gas chromatography is a type of column chromatography that uses gas as the mobile phase. Depending on the state of the stationary phase used, it can be divided into gas-solid chromatography (GSC) and gas-liquid chromatography (GLC). 　　2 Principles of Gas Chromatography The mobile phase in gas chromatography is an inert gas; in gas-solid chromatography, an adsorbent with a large surface area and certain activity is used as the stationary phase. When a multi-component mixed sample enters the chromatography column, due to the different adsorption forces of the adsorbent on each component, after a certain period of time, the migration speeds of these components within the column also differ. Components with weak adsorption forces are easily desorbed and leave the chromatography column to enter the detector first, while components with the strongest adsorption forces are the least likely to be desorbed, and therefore leave the chromatography column last. In this way, the various components are separated from one another in the chromatography column, and enter the detector in sequence to be detected and recorded. 　　3 Gas Chromatography Process The carrier gas flows out of a high-pressure cylinder; after its pressure is reduced to the desired level using a pressure regulator, it passes through a purification and drying tube to be cleaned. Following this, it goes through a pressure stabilizer and a rotameter, and then flows at a constant pressure and speed into the vaporization chamber where it mixes with the vaporized sample. The resulting sample gas is then sent to the chromatography column for separation. The separated components flow into the detector one after another with the carrier gas, and then the carrier gas is vented. The detector converts changes in the concentration or mass of a substance into a specific electrical signal; after amplification, this signal is recorded on a recorder, resulting in the chromatography elution curve. 　　Qualitative analysis can be performed based on the retention time of each peak obtained from the chromatography elution curve, while quantitative analysis can be carried out using the area or height of the peaks. 　　4 Gas Chromatograph It consists of the following five systems: gas path system, injection system, separation system, temperature control system, and detection and recording system. 　　Whether the components can be separated depends on the chromatography column ； Whether the separated components can be identified depends on the detector; therefore, the separation system and the detection system are the core of the instrument. 　　5 Gas Chromatograph There are many types of detectors available, among which the commonly used ones include: Hydrogen Flame Ionization Detector (FID), Thermal Conductivity Detector (TCD), Nitrogen Phosphorus Detector (NPD), Flame Photometric Detector (FPD), Electron Capture Detector (ECD), and others