The detectors used in a GPC system monitor the separation and respond to the components and/or fractions as they elute from the column.
PRINCIPLES OF GPC 359
Detectors must be sensitive and must have a wide linear range in order to respond to both trace amounts and large quantities of material, if necessary. They must be nondestructive to the eluting components if they are to be collected for further analysis. There are different types of detectors for GPC, the most common ones being the refractive index (RI) detector, the UV detector, viscometer detector, as well as light scattering and infrared detectors. Since all compounds refract light, the RI is known as a “universal” detector. It is the most widely used detector to monitor the MWD. The refractive index of polymers is constant above approximately 1000 Da. Therefore, the detector response is directly proportional to the concentration. In addition to the information about MW averages and distribution obtained with the RI detector, UV absorbance detectors may provide information about composition. UV detectors are used for polymers containing chromophore groups. Online light scattering detectors and viscometers provide information about the polymer structure. If a light scattering detector is used together with an RI, then it is not necessary the use of polymer standards to calibrate the equipment, since light scattering gives the absolute weightaverage MW (Mw). Light scattering detectors also measure the radius of gyration. Viscometer detectors also provide information about the intrinsic viscosity of the polymer and the level of branching (index of branching) of the polymeric chains. The more the number of detectors coupled to the GPC equipment, the more detailed is the structural and chemical information of apolymer that can be obtained.
ตรวจจับที่ใช้ในระบบ GPC แยกการตรวจสอบ และตอบสนองต่อส่วนประกอบและ/หรือเศษส่วนเป็นพวก elute จากคอลัมน์หลักการของ GPC 359Detectors must be sensitive and must have a wide linear range in order to respond to both trace amounts and large quantities of material, if necessary. They must be nondestructive to the eluting components if they are to be collected for further analysis. There are different types of detectors for GPC, the most common ones being the refractive index (RI) detector, the UV detector, viscometer detector, as well as light scattering and infrared detectors. Since all compounds refract light, the RI is known as a “universal” detector. It is the most widely used detector to monitor the MWD. The refractive index of polymers is constant above approximately 1000 Da. Therefore, the detector response is directly proportional to the concentration. In addition to the information about MW averages and distribution obtained with the RI detector, UV absorbance detectors may provide information about composition. UV detectors are used for polymers containing chromophore groups. Online light scattering detectors and viscometers provide information about the polymer structure. If a light scattering detector is used together with an RI, then it is not necessary the use of polymer standards to calibrate the equipment, since light scattering gives the absolute weightaverage MW (Mw). Light scattering detectors also measure the radius of gyration. Viscometer detectors also provide information about the intrinsic viscosity of the polymer and the level of branching (index of branching) of the polymeric chains. The more the number of detectors coupled to the GPC equipment, the more detailed is the structural and chemical information of apolymer that can be obtained.
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