SGIC 2D

Comprehensive Two-dimensional Liquid Chromatography at Elevated Temperature.
Two dimensional separation, for detailed study of chemical composition – molar mass bivariate distribution with the advantages of using IR detector for identification and quantification of copolymers.

SGIC 2D

SGIC 2D Overview


The Two-Dimensional Solvent Gradient Interaction Chromatography (SGIC 2D) instrument performs an analytical fractionation of the polymer according to chemical composition by selective adsorption/desorption on an HPLC column, followed by a second separation according to molar mass on a Gel Permeation Chromatography (GPC) / Size Exclusion Chromatography (SEC), being the only high-temperature SGIC system available in the market.

The instrument is fully automated and the whole process is controlled by the virtual instrumentation software. Once the vials with the dry polymer samples are placed in the autosampler’s external tray, the instrument takes care of the vial-filling with solvent, dissolution with gentle shaking, optional in-line filtration, and injection into the HPLC column. Then the solvent gradient program starts, and the resulting fractions are injected towards the GPC/SEC columns.

The detection is done by a standard infrared detector at the exit of the GPC/SEC columns, which provides a linear response and outstanding stability, overcoming this way the limitations in detection found in single dimension SGIC due to the varying mobile phase composition.

At the end of the analysis, the two-dimensional distribution interrelating molar mass and chemical composition are obtained. This combined information is often required for the comprehensive characterization of complex materials. The SGIC 2D is especially suitable for the analysis of samples of low crystallinity or complex polarity distribution when the classic cross-fractionation technique based on crystallization (TREF/GPC) does not provide the desired separation.

Polymer Char’s analytical SGIC 2D instrument is a practical alternative to preparative fractionation methods, which are sometimes tedious and time-consuming. The composition molar mass interdependence is now measured in hours instead of days, with limited solvent consumption and no manual intervention, in an intrinsically safe set-up.

The SGIC 2D can also be used as a regular High-temperature GPC/SEC equipment without the need to modify anything in the hardware or additional steps by the user. The smart design and powerful control software allow the instrument to run in either SGIC 2D mode or in a regular GPC mode.

SGIC is a technique developed and patented by The Dow Chemical Company and licensed to Polymer Char. 

SGIC 2D Features

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The Two-Dimensional Solvent Gradient Interaction Chromatograph (SGIC 2D) instrument performs an analytical fractionation of the polymer according to chemical composition by selective adsorption/desorption on an HPLC column, followed by a second separation according to molar mass on a GPC/SEC column. The two-dimensional distribution interrelating molar mass and chemical composition is obtained. This combined information is often required for comprehensive characterization of complex materials. The SGIC 2D is especially suitable for the analysis of samples of low crystallinity or complex polarity distribution

Fully-automation throughout the whole process, including vials filling with any of the available solvents. Therefore, there is no manual handling of solvents at any moment: once the vials containing the dry samples are placed on the autosampler room temperature tray, the instrument takes care of the rest of the steps involved, with no vial transfer. An in-line filter with backflush cleaning is incorporated, automating this step as well.

Dissolution time can be programmed individually for each vial, therefore, thermal degradation is minimized. Furthermore, a gentle shaking movement inside of the autosampler oven, helps in speeding up the dissolution process, without the shear stress due to magnetic stirring bars. In addition, oxygen can be removed from the vial by the automated nitrogen vials-purge system, in order to prevent oxidation of the dissolving polymer molecules.

Advantages of using an IR detector

Linear response to polymer concentration. No additional utilities required (gas supply or extraction of vapors). Identification of chemical structures and quantification of copolymers chemical composition.

This allows the optimization of sample separation and accommodation of columns of different sizes. First and second dimension flow rates, injection volumes, and 2D valve switching time, as well as gradient profile and system temperatures, can all be defined by the user and saved as a method file.

SGIC 2D is designed to have an easy access to each component and facilitate the maintenance tasks when needed.

Analysis of multiple samples

Automated analysis of a sequence of samples, with flexibility to use different methods for each one.

It is possible to use the instrument as a regular, high-temperature GPC/SEC as well through software control, without having to perform any modifications to the equipment.

SGIC 2D Detectors

The following are the detectors available for SGIC 2D:

IR4

IR4

The IR4 is the standard Detector integrated by default in all the Polymer Char analytical instruments. IR4 is a dual-wavelength infrared detector, which uses the principle of infrared absorption spectroscopy to measure the concentration and composition in polyolefins.

IR5

IR5

The IR5 is a high sensitivity infrared detector designed for measuring concentration and short-chain branching with superb stability. It incorporates interference filters at five different wavelengths and a thermoelectrically cooled MCT detector with high sensitivity (no liquid Nitrogen required).

IR6

IR6

The IR6 Detector is the latest IR Detector developed by Polymer Char, with the same performance and sensitivity than IR5 Detector and the additional capability of measuring carbonyls group in the band of 1740 cm-1. We recommend the IR6 Detectors for users willing to analyze polyolefin type EVA, EBA, and others with carbonyls group present in the IR band above.

SGIC 2D Software


The SGIC 2D Virtual Instrumentation Software controls the whole analytical process combining the first dimension SGIC analysis with continuous injection of fractions to the second dimension GPC analysis. The whole process is automated from the sample preparation to a final cleaning of lines and reconditioning of interaction chromatography columns. Therefore, there is no solvent handling by the operator and when an analysis is finished the instrument is ready to start a new run.

Analysis conditions are flexible so they can be specifically adapted to each sample requirements or columns specifications; software can manage all needed SGIC fractions and GPC analysis time. Additionally, parameters related to the analytical process such as solvent gradient time and composition, first and second dimension pumps flow rate, temperature and second dimension analysis time among others can be set from the software analysis conditions screen and saved as a method file.

Different method files can be selected for each vial in the analysis run queue and the start of the analysis can be as simple as putting the samples into the vials in the autosampler room temperature tray and pressing the Start button in the software. The results can be reviewed and processed when its analytical process is finished, even though the instrument is running other samples.

Molar mass (GPC column) and chemical composition (IR) calibration tools are integrated in the same software package, in order to obtain quantitative data.

The SGIC 2D Software includes a powerful calculations package, capable of obtaining directly the 3-dimensional graph to study the interdependence of the Molar Mass and the Chemical Composition Distribution of each sample. In addition to the 3D plot, the first dimension recovered interaction chromatography profile is obtained based on fractions peak areas. Chemical composition information as measured by the IR detector, as well as molar mass average are overlaid so the different peaks in the recovered chromatogram can be identified and the polymer features in microstructure characterized in detail.

The analyzed samples can be reviewed at any time thanks to the database installed in the software package and linked to the calculations screens. Raw and processed data can be exported to ASCII format.

One of the biggest and most powerful attributes of this software is that it allows the user to change the instrument from an SGIC 2D mode to a high-temperature GPC/SEC mode without having to make any alterations in the hardware. The user doesn’t need to perform any steps other than making the change through the software.

SGIC 2D FAQs


The Two-Dimensional Solvent Gradient Interaction Chromatograph (SGIC 2D) instrument performs a fractionation of the polymer according to composition by solvent gradient HPLC technique in adsorption mode followed by a second separation by Gel Permeation Chromatography (GPC/SEC) of the fractions eluted from the first dimension. It is especially suited for the separation of complex and heterogeneous materials with low or no crystallinity. It allows a detailed study of the microstructure of such materials by providing their chemical composition molar mass bivariate distribution. In addition to that, the build-in IR detector allows identification of the separated fractions and comonomer quantification in the case of copolymers.

No, SGIC 2D is an analytical scale instrument and does not provide physical fractions.

Different vials can be loaded into the instrument autosampler (up to 42) and they will be analyzed sequentially, using the same or different analytical methods. However most of the time the number of vails that can be run unattended is limited by the solvent reservoir capacity given the high flow rate typically applied in the second dimension. In practice 3 to 5 samples can be run under standard conditions in one day. The actual analysis time and solvents consumption are very dependent on analysis conditions.

The standard amount used in SGIC 2D analysis is around 30mg.

A pair of poor/good solvents are typically chosen to generate the first dimension mobile phase gradient (in general two solvents of different polarity or solubility power). Poor solvents used in polyolefin analysis are decane, 1-decanol, ethylene glycol monobutylether (EGMBE) among others, while 1,2,4-Trichlorobenzene (TCB) or ortho-dichlorobenzene (o-DCB) are commonly used as good solvents.
For the second dimension, GPC/SEC separation a good solvent compatible with IR detection must be used (TCB, oDCB,…).
Guidelines on solvent pairs for SGIC 2D can be found in literature and in the “SGIC 2D Documents” section.
Before using other solvents please consult with Polymer Char first.

No sample preparation is required by the user but weighing the dry samples and putting them inside of the vials in the autosampler tray. The rest of the steps are performed by the instrument automatically: filling, dissolution, vials filling, sample dissolution, injection, solvents gradient, as well as rinsing of the valves and lines. Therefore, when a run is finished, another can be started immediately.

No sample preparation is required by the user but weighing the dry samples and putting them inside of the vials in the autosampler tray. The rest of the steps are performed by the instrument automatically: filling, dissolution, vials filling, sample dissolution, injection, solvents gradient, as well as rinsing of the valves and lines. Therefore, when a run is finished, another can be started immediately.

Before starting a new analysis, the user has to refill the solvents bottles as required to ensure there is enough of each of them for the run, as well as empty the waste bottle so there is enough room to collect all waste generated. Polymer Char’s Solvents Handling Trolley (SHT) is recommended to facilitate those tasks.

SGIC 2D incorporates an infrared (IR) detector to collect concentration chromatogram after GPC separation from each fraction going out of the Interaction chromatography column.
The IR detector can be Polymer Char’s IR4/IR5/IR6 models, which simultaneously provide chemical composition information.
The use of the higher performance IR5/IR6 detectors is Polymer Char's recommendation for this instrument for accurate quantification of minute polymer fractions generated in this technique.

The SGIC 2D instrument incorporates an interaction chromatography (IC) column, which is typically located in the instrument top oven together with valves and other parts. The more delicate GPC column is located and isolated in the main oven, always kept at a constant high temperature for its optimum preservation.
Optionally the location of the columns can be exchanged in case of requiring temperature programming on the IC column. Temperature programming is only possible in the instrument main oven.

The user only needs to select the mode through the control software and the instrument will automatically switch between modes after receiving the order from the software. No modifications to the hardware are necessary for the equipment to change from one mode to the other.

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