Content1. What is post column derivatization system?
1.1 Working principle of post column derivatization system
1.2 Feature of post column derivatization system
1.3 Application of post column derivatization system2 Pre column and post column derivatization
2.1 Pre-column derivatization
2.2 Post-column derivatization3 How to buy post column derivatization system?
What is post column derivatization system?
are experimental methods that use derivatization reactions to react the analytes with the corresponding reagents to change their physical or chemical properties so that they can be detected. For example, the chromophores or fluorescent groups are bonded to the sample to multipole amplification, making the detection more sensitive. Post-column derivatization system
sets new standards for post-column derivatization system performance, price and form. The unique reactor design has resulted in a new generation of post-column derivatization systems
with high performance and low price.Post-column derivatization systems
are used to increase the detection sensitivity or improve the analytical method for samples such as amino acids, proteins, and sugars. With this method, column separates are mixed with derivatization reagents prior to entering the detector, improving detection sensitivity or using the properties of the new material produced after derivatization to select a more selective detector. Post-column reaction systems can be used to derivatize or perform other reactions for fluorescent, electrochemical, refractive and UV/Visible detectors.Post-column derivatization
also uses photochemical derivatization and electrochemical derivatization. Photochemical derivatization is a method that uses light with certain properties to irradiate a target to cause a chemical change or alter its chemical properties. Electrochemical derivatization is a method in which a specific voltage is applied to a target in some way to cause it to be oxidized to a substance with strong fluorescence.
Working principle of post column derivatization system
The post-column derivatization
principle of the post-column derivatization system
refers to the process of injecting a multi-component mixed sample into a chromatographic column, separating it under selected chromatographic conditions, and when each component exits the column, it reacts with the derivatization reagent successively under certain reaction conditions, and the resulting derivatization products are then sequentially detected by the detector.
The post-column derivatization system
is used for the online photo derivatization of aflatoxin by liquid-phase fluorescence detection, which can effectively enhance the fluorescence intensity of aflatoxin B1 and G1 without any chemical reagent, and the sensitivity of aflatoxin B1 and G1 can reach above 0.5 ppb. In addition, the method is also suitable for the online derivatization of barbiturates, amino acids, peptides, vitamins and sulfonamides.
The advantage of the post-column derivatization technique is that the derivatization reaction and reaction products do not have to be very complete and stable, but the following conditions need to be met.
a. Rapid and reproducible response.
b. No detection response of the reagent itself.
c. The volume of the reagent is small so that the dilution of the product and the dilution causes the peak spread to be as small as possible.
d. High precision of reactor temperature control.
e. High precision flow control of derivatization reagents.
Feature of post column derivatization system
A. Quick and easy setup
The post-column derivatization system can be installed by simply connecting an inlet from the column and an outlet to the detector.
B. Modular design
a. Single or double reaction cores are available.
b. Two-step reaction process with simultaneous heating reaction as well as ambient temperature reaction.
c. Option of 1, 2 or more derivatized pumps.
d. Reduced risk of joint and line connections to prevent leakage.
e. All connection fittings are located on the front panel for user convenience.
C. Panel display for easy setting
a. The front panel of the reactor shows the set and actual temperature of each reaction core.
b. The front panel of the derivative pump shows the flow rate, pressure and pressure limit of each reagent.
D. External control
a. Pump flow rate and reactor temperature can be controlled from the front panel or externally.
b. Modular reactor with only 2 connectors for reactor core replacement.
c. New design of the reactor core, which greatly reduces the diffusion of peaks.
d. Full PEEK flow path of the system.
a. Real-time online derivatization of aflatoxin B1 and G1 without the use of chemicals, avoiding the operator's exposure to toxic chemicals.
b. No corrosive acid flow through the capillary, increasing the life of the HPLC instrument.
c. No rinsing step and no additional maintenance requirements.
d. The results were superior to electrochemical methods, iodine/bromine derivatization.
Application of post column derivatization system
|Post column derivatization system
|General application||Analyze application
|Determination of glycerol phosphate by derivatization method||Determination of ammonia methyl ester pesticides and residues by derivatization method
|Determination of taurine in food||Determination of aflatoxin by iodinated derivatization method
|Determination of amino acids by derivatization method||Herbicide residue analysis
|Determination of amino acids by ninhydrin derivatization||Voglibose
Structure of post column derivatization system
Post-column derivatization system is a device that enables post-column derivatization. It is mostly used in liquid chromatography systems. Samples are mostly detected by fluorescence detectors and a small number of UV detectors. The samples detected are mainly toxins and pesticide residues, and the purpose is to improve the response of the detector to the target.
a. Post-column derivatizers are mainly composed of a derivatization pump and a derivatization cell. Some post-column derivatizers are equipped with column temperature chamber and degasser.
b. Derivative pumps are medium to high-pressure microflow pumps or analytical pumps. Derivative pumps do not require high-pressure resistance, and a pressure limit of up to 5MPa is sufficient. The flow rate is generally at 0.5 ml/min. The flow rate repeatability requirement is high and cannot exceed 0.5%.
c. The derivatization cell consists of a derivatization tube and a temperature control system. The temperature of the derivatization cell is generally above room temperature-130℃, and some can reach 180℃. The volume of the derivatization cell is generally 0.1ml-3.0ml.
d. Derivative tubes are generally made of FEP tubes with a 0.25 mm inner diameter.
Pre column and post column derivatization
The most important purpose of derivatization is to improve the detectability of the target. For GC, most of them are to enhance the volatility or improve the polarity of the target; for HPLC, most of them are to improve the detector response to the target.
Derivatization can be divided into pre-column derivatization and post-column derivatization.
Pre-column derivatization reacts the analyte with the derivatizer before passing through the analytical column to achieve separation of the reaction products on the analytical column. The actual separation is the derivative product, and the detection is also the derivative product.
Post-column derivatization is a method in which the isolate is reacted with a derivatizer in a derivatization cell after separation is achieved in the analytical column. What is separated in the column is the target and the derivatization product is detected at the detector.
The applicable compounds for derivatization are biological acids/bases, amines, antibiotics (polyether antibiotics are mostly seen) and amino acids. The derivatizer must be in excess and stable. If the reaction is incomplete without excess, leading to inadequate detection and poor reproducibility due to instability. Derivatives, derivatives and derivative by-products are at least well separated. The derivatization reaction needs to be fast and complete. If the reaction is slow, pre-column derivatization can continue, but post-column will lead to failure. Because the flow rate is fixed and the length of the derivatization cell line is a certain length, the time left for derivatization is a certain amount of time. The pre-column derivatization can be done outside the system after the derivatization is completed, but it also affects the efficiency.
Pre-column derivatization is the chemical reaction of the sample with certain chemical reagents prior to chromatographic separation to prepare the target compounds in the sample into appropriate derivatives, which are then separated and detected by chromatography.
a. Compared to post-column derivatization, the reaction conditions can be freely selected.
b. There is no limitation of reaction kinetics.
c. The derivative by-products can be pretreated.
d. Easily allows multi-step reactions to proceed.
e. There are more derivatives to choose from.
f. No complex instrumentation is required.
g. Little requirement for equipment, manual derivation can be operated.
h. Relatively broad requirements for derivation time
a. The derivatization by-products formed may cause greater difficulties for chromatographic separation.
b. During the derivatization process, impurities are easily introduced or lead to loss of samples.
a. The formation of by-products is not important and the product does not need to be highly stable, only good reproducibility is required.
b. The analytes can be separated in their original form, and it is easy to choose existing analytical methods.
a. Requires additional equipment, which is more demanding on the instrument.
b. Reactor can cause peak broadening and reduce resolution.
c. Excess reagents can cause interference.
How to buy post column derivatization system?
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