What are the main evaluation indicators of gas chromatography

The main evaluation indexes of gas chromatography are as follows:

1. The sensitivity of the detector directly affects the accuracy of the detection data;

2. The complexity of the operation, the simpler the operation, the better, the high, the more configurable and adjustable, the better;

3. Workstations, some workstations are complex to operate, and the generated atlas is not compatible with Word;

4. Gas system, the influence of the gas system is relatively large, and the more stable the gas control, the better;

5. Brand, big brand, it is good to buy accessories when it is broken in the future.

Sensitivity, limit of detection.

Stability.

In gas chromatography, the parameters used for qualitative use are:Retention time

Gas chromatography.

The original question is as follows: In gas chromatography, the parameter used for qualitative is ().

a. Retention time.

b. Allocation ratio with deficit.

c. Half-peak width.

d. Empty excavation of the peak surface.

Answer: A Extension: Meaning: Gas chromatography uses gas as a moving phase chromatography. Depending on the stationary phase used, it can be divided into two categories: the stationary phase is solid, which is called gas-solid chromatography; If the stationary phase is liquid, it is called gas-liquid chromatography.

Basic classification: internal standard method, absolute standard curve method, peak area percentage method.

Scope of application: application in health testing, application in medical testing, and application in pharmaceutical analysis.

In gas chromatography, the parameter that can be used for quantification is peak area.

The peak area ratio refers to the total area above the background line in the chromatogram, indicating the amount of analyte, the larger the area, the higher the content. The internal standard method is an indirect or relative method of calibration. When analyzing the content of a component in a sample, an internal standard is added to calibrate and eliminate the effects of fluctuations in operating conditions on the analytical results to improve the accuracy of the analytical results.

Internal standard method is an important technique in gas chromatography quantitative analysis. When using the internal standard method, a ridge quantitative reference material is added to the sample, which can be separated by chromatography and is not interfered by other component peaks in the sample, as long as the peak area and relative response value of the internal standard and the component to be measured are measured, the percentage content of the component to be measured in the sample can be obtained.

The selection of internal standards is a very important task when using internal standard method. Ideally, the internal standard should be a known compound that can be purified so that it can be added to the sample in an accurate and known amount, and it should have substantially the same or as much as possible consistent physicochemical properties, chromatographic behavior, and response characteristics with the sample components being analyzed, preferably a homolog of the substance being analyzed.

Of course, in chromatographic analysis, the internal standard must be sufficiently separated from the components in the sample. It should be pointed out that in a few cases, the analyst may be more concerned about the rate of the compound obtained in a complex process, and in this case, he can use a compound that is easily completely selected in this process as an internal standard to determine the percentage of the compound of interest.

External standard method

External standard method A quantitative method in chromatography that does not add a reference material to the sample being tested, but is determined separately under the same chromatographic conditions as the sample being tested.

The content of the measured component is obtained by comparing the obtained chromatographic peak area with the chromatographic peak area of the measured component. The external standard and the measured component are the same substance, but it is required to have a certain purity, and the concentration of the external standard should be close to the concentration of the analyte during analysis, so as to facilitate the accuracy of quantitative analysis.

Hello, dear, according to the questions you provide, here for you to find the following: gas chromatography is a method for analyzing the separation and quantification of substances, with the following characteristics:1

Separability: Gas chromatography separates different kinds of substances through the interaction between gas phase molecules. 2.

Sensitivity: Gas chromatography can detect and separate very small molecules and compounds, and is commonly used to detect and separate organic compounds, microorganisms, nano-dissecting materials, etc. 3.

High resolution: GC can achieve high-resolution chain separations by selecting the appropriate GC column and injection system. 4.

Quantitative accuracy: Gas chromatography can provide high-precision quantitative results, and is often used to determine the number, molecular weight, concentration, etc. of molecules. 5.

High efficiency: Gas chromatography can complete the analysis in a short time and is often used for on-site testing, semi-quantitative analysis, etc. Gas chromatography quantification methods typically include:

1.Inlet gas chromatography: This method involves feeding a sample into a gas chromatograph and separating it using the interaction between gas phase molecules.

2.Inlet GC-MS: This method combines inlet gas chromatography and mass spectrometry to detect and separate two different types of molecules simultaneously.

3.Gas chromatography-infrared spectroscopy: This method combines gas chromatography and infrared spectroscopy to separate and detect different molecules.

These three methods can be combined to achieve more complex quantitative methods.

A measure of column selectivity is resolution.

The main function of the column is to separate the analytes in human samples, common types: analytical, preparative, **range:

There may be differences between different types and manufacturers. The chromatographic column is composed of column tubes, pressure caps, ferrules, frits, connectors, screws, etc., which are used in conjunction with analytical equipment to separate the analytes in the test samples.

Instrument use: Used in conjunction with analytical equipment to separate analytes in a sample. How it works:

Column chromatography, also known as chromatography, is a partitioning method with partition equilibrium as the mechanism. The chromatographic system consists of two phases, one stationary and one mobile.

When the two phases move relative to each other, the difference in the distribution equilibrium properties of the components contained in the mixture is repeatedly used to achieve the purpose of separating each other. The chromatogram where the stationary phase is more polar than the mobile phase is normal-phase chromatography, and the opposite is reversed-phase chromatography. According to the principle of sock-like socks, the mixture is released from the column after the physitic destruction of the solubility in the stationary phase, which has a long retention time and is difficult to be eluted.

The :* of devices is different, and there may be differences between different types and manufacturers of devices, which are subject to the actual situation. Who is it used for:

Columns are used by professionals who have specialized knowledge and skills to separate analytes from their samples. Applicable age: There is no special age limit.

How to use:

The choice of column will affect the quality of the separation, and different brands and different series of the same brand have different functions, and some can tolerate low pH values. There are those that are resistant to high temperatures, and those that are suitable for alkaline samples.

Methodological evaluation indexes of chromatographic quantitative analysis:

1. The sensitivity of the detector directly affects the accuracy of the detection data;

2. The complexity of the operation, the simpler the operation, the better it is to use the buried stove, and the higher the one, the more configurable and adjustable the better;

3. Workstations, some workstations are complex to operate, and the generated atlas is not compatible with Word;

4. Gas system, the influence of the gas system is relatively large, and the more stable the gas control, the better;

5. The brand, the brand is big, and the liquid is good to buy accessories when it is broken in the future.

Extended Information: Definition of Gas Chromatography:

Gas chromatography is a chromatographic technique used in organic chemistry to separate and analyze compounds that are prone to volatilization without decomposition. Typical uses of gas chromatography include testing the purity of a particular compound and separating the components in a mixture (as well as determining the relative levels of each component), and in some cases, it may also be helpful in the characterization of compounds. In miniature chemistry experiments, gas chromatography can be used to prepare a pure product from a mixture.

Gas chromatography (GC) is a type of chromatography. There are two phases in chromatography, one is the mobile phase and the other is the stationary phase. If a liquid is used as the mobile phase, it is called liquid chromatography, and if a gas is used as the mobile phase, it is called gas chromatography.

Gas chromatography can be divided into two types due to the different phases used in the stationary shed, which is called gas-solid chromatography with solid adsorbents as the stationary phase, and gas-liquid chromatography with the monomer coated with the stationary liquid as the stationary phase.

According to the principle of chromatographic separation, gas chromatography can also be divided into adsorption chromatography and partition chromatography, in gas-solid chromatography, the stationary phase is the adsorbent, the gas-solid chromatography belongs to adsorption chromatography, and the gas-liquid chromatography belongs to the distribution chromatography.

I don't believe it, I can't log out and send it.

Chromatographic Condition Optimization Principle: Obtain the resolution that meets the analytical requirements in the shortest possible timeThe specific condition optimization principle is:

1. Optimization of sample processing methods.

Second, the correct configuration of the instrument is optimized.

1. Selection of chromatographic column.

2. Selection of detector.

3. Optimization principle of operating condition setting.

1. The optimization of injection volume includes according to the sample concentration, column capacity, detector sensitivity 2, injection port temperature optimization according to the boiling point of the sample and the use temperature of the column 3, the column temperature according to the complexity of the sample and the vaporization temperature, the initial temperature is the boiling point of the lightest component, the final temperature is the boiling point of the most recombinant component, and the heating rate depends on the complexity of the sample.

4. The principle of temperature setting of the detector is to ensure that the components will not condense, and at the same time meet the sensitivity requirements of the detector.

5. The principle of carrier gas velocity setting is easy, it can be set by 10% of the best high, and then adjusted according to the degree of separation.

Weather chromatography detection conditions are recommended.

Chromatographic conditions: second-order heating, initial temperature 60, initial time 1 minute, termination temperature 125, termination time 6 minutes, heating rate 15Column equilibration time 1 min, injector 110, detector 260, second-order rate 20, stop temperature 230, stop time 2, volume 7, hydrogen, pre-column pressure, sweep 7, tail blow 5, carrier gas, air 8, injection volume μl.

Why can't I send my answer for two days, and it says it's being submitted???

The parameter used to evaluate the symmetry of the chromatographic peaks is: tailing factor

The tailing factor is a parameter that evaluates the peak shape by calculating the ratio of peak width at 5% peak height to the distance from the peak peak to the leading edge, in order to ensure the chromatographic separation effect and measurement accuracy, and is often expressed by t. t (tailing factor) = tailing factor (t) - t, which is used to measure the symmetry of chromatographic peaks.

It is also known as a symmetryfactor or asymmetryfactor. The Chinese Pharmacopoeia Liquid Wheel stipulates that t should be. t is the forward extension peak, and t is the trailing peak.

Asymmetry (assymmetry) = the peak width at 10% of the peak height, and D1 is the distance from the peak peak to the peak front.

Obviously, as and t cannot be directly equated, and most chromatography theory books use data measured at 10% of peak height (some use 5%, but rarely) to calculate asymmetry according to the above formula; The tailing factor is measured at 5% of the peak height and is calculated according to the formula above. In the Chinese Pharmacopoeia and the United States Pharmacopoeia, this method is required for the measurement and calculation of asymmetry of chromatographic peaks.

The qualitative basis is: the reference material is used for comparative qualitative purposes. (Each species has a definite retention value under certain chromatographic systems and operating conditions, and it is possible to identify what each chromatographic peak represents) by comparing the retention values of the sample components with the known components).

It can also be characterized by relative retention values, chemical reaction conditions, and two spectra.

Quantitation is based on the fact that peak area or peak height is proportional to the content of the component under certain experimental conditions, so peak area or peak height can be used for quantification. Its quantitative methods include normalization method, internal standard method and external standard method.

Gas chromatography is a chromatic separation analysis method that uses gas as a mobile phase. The vaporized specimen is brought into the column by a carrier gas (mobile phase), and the stationary phase in the column has different molecular forces with each component in the sample, and each component flows out of the column at a different time, and the components are separated from each other.