Common Detectors for GPC/SEC Chromatography

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The Advantages of Combo Instruments

A concentration signal must be available to perform the required calculations when utilizing a viscometer within a GPC/SEC system. The challenge is that the DRI Detector, which is normally used for this task, must provide a concentration signal that corresponds to each point on the viscosity curve.

This can be achieved with two individual instruments, but the accuracy of the results will be restricted because of the volume difference of the detectors. Combo instruments integrate both detectors to overcome this challenge and provides a superior analysis of the sample being investigated.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

The AYE Combo

For the identification of the intrinsic viscosity in highly diluted samples, the AYE Combo Refractometer/Viscometer has set a new standard. The refractometer is an essential component of the viscometer, where both viscosity and concentration are calculated simultaneously on the same region of a sample.

A much more precise determination of molecular parameters is provided by the AYE Combo, which is especially suited for applications that center on the branching and structure of an investigated polymer.

Common Detectors for GPC/SEC Chromatography

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The Advantages of dn/dc Refractometers

The specific refractive index (dn/dc) is one of the parameters necessary for the quantification of absolute molecular weight in Static Light Scattering (SLS). The importance of this parameter becomes evident when looking at the construction of the Debye Constant utilized for calculations in which the dn/dc is a squared term.

A marginally small error in dn/dc will produce a two-fold error in molecular weight. It must be noted that the dn/dc value should be acquired at the same wavelength as the laser utilized for Light Scattering or an additional unknown error will be introduced.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

The AYE dn/dc Refractometer

It is simple to identify the specific refractive index (dn/dc) of any dissolved sample using the batch mode of the AYE dn/dc Refractometer with only a few syringes required.

Using the AYE dn/dc Refractometer to measure a series of concentrations in the investigated sample will yield reproducible and reliable results within minutes. A large quantity of wavelength selections are available to ideally match the laser employed in SLS, ensuring optimal results.

Common Detectors for GPC/SEC Chromatography

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The Advantages of a DRI

A Differential Refractive Index Detector (DRI) is the most widespread and flexible detector in GPC/SEC chromatography. It yields a wide linear range, high sensitivity, and can analyze almost any dissolved compound. It has been the preferred detector for several years for this reason.

It can be used as the only detector in a basic GPC/SEC system or can be the source of concentration information in a more advanced system with a MALS detector and/or a viscometer. The applications for this detector are endless, because of this the DRI is certainly the most practical detector for the majority of applications requiring polymer characterization.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Why Choose the AYE DRI?

GPC/SEC chromatography with a MALS detector is a highly effective system that can provide absolute values of the compound being investigated. It is essential to acquire concentration data in addition to the molar mass in order to perform this. In this example, a standard DRI will be unable to provide data obtained at the same wavelength as the laser employed in the MALS Detector.

A significant error will then be introduced for all calculations executed, which detracts from the accuracy of the obtained results. The AYE DRI functions at the same wavelength as the MALS detector, enhancing the reliability of results.

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The Advantages of UV Detectors

UV Detectors deliver unparalleled selectivity and sensitivity as detectors of concentration in GPC/SEC. The only restriction is that the solvent used must provide a window in the absorption range of UV light and the sample must include chromophoric groups.

When these requirements are met, a UV Detector is highly effective as a sole concentration detector in a GPC/SEC system or can be integrated with a DRI detector to determine the composition distribution of copolymers.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

The AYE UV Detector

The AYE Rapid Scanning UV integrates a vast linear range of more than four orders of magnitude, a high sensitivity, and flexibility to suit any application, with a solid physical base of wavelength precision and a clearly defined bandwidth.

It provides detection at two wavelengths with the option to expand this to four wavelengths, meaning it is ideally suited for applications requiring the characterization of complex copolymers.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

The Advantages of Viscometers

A viscometer enables a universal calibration to be used within a GPC/SEC chromatography system. The molecular weights determined through this technique are independent of the polymer standards employed to construct the calibration, which means they closely correspond to absolute values.

Additional molecular parameters can be determined using a viscometer, which reveals information about the physical composition of the polymer being analyzed. This even offers a method of determining branching parameters.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

Why Choose the AYE Ultrasensitive Viscometer?

The AYE Viscometer, along with all viscometers for GPC/SEC on the market currently, are based on the quantification of differential pressure throughout a capillary network.

TESTA has been able to significantly decrease the level of noise and enhance sensitivity by more than an order of magnitude in comparison to all other available viscometers.

This advancement means that usage can be allowed at significantly lower flow rates than what has been possible before. It is also possible to perform detection at lower concentrations and lower molecular weights. Semi-micro applications are easily achieved at present.

Common Detectors for GPC/SEC Chromatography

Image Credit: TESTA Analytical Solutions

This information has been sourced, reviewed and adapted from materials provided by TESTA Analytical Solutions.

For more information on this source, please visit TESTA Analytical Solutions.

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