GPC Guide
Preparation of Samples
  • For the standards: cut the strip into the vial with 2mL of solvent. Label these A and B respectively. The caps are to be put on with the shiny PTFE coated side down towards the solvent. They will take 20 minutes to dissolve
  • For the samples: dissolve about 5mg of polymer in 2mL of desired solvent, and leave for up to 20 minutes for it to fully dissolve. Filter the sample into a vial for the autosampler using the syringe filters around the GPC area. Fit the cap onto the vial with the PTFE (shiny) side facing down into the vial.
  • If you want to have a marker to show when the sample has all been processed toluene can be added which will show as a peak in the very low weight region. Toluene should be added so that it is 2micrograms per mL.
PL Instrument Control
  • ‘Autosampler’ gives a picture of the sample tray
  • ‘Injection valve’ manual sample introduction
  • ‘Pump’ has a minimum setting to stop air being blown through the columns, Flow rate is suggested at 1ml/min but for conservation of solvent a lower flow rate is suggested for standby
  • ‘Oven’ range between 0-50C
  • ‘Detectors’ these cover the refractive index. You can auto-zero the baseline here and perform purges recommended for when the baseline is unsteady. After the system has been on standby it is recommended to purge to remove old solvent from the detectors for a few minutes
  • ‘Monitor’ and ‘Settings’ Displays the system settings.
To enter a sample for analysis:
  • Double click the site the sample is situated in, or you can click the table with the reference to the site.
  • After a purge to remove old solvent and the set up of the workbook, as shown below in GPC Online, you click ‘sample injection’ and ‘go’.
GPC Online
This program is used to collect the sample data. First create a new workbook:
  • The template used is IC-THF.
  • Type a name, then click ‘ok’.
  • The conditions we use are all set in there and don’t need to be changed; they are simply for the records.
  • The data collection needs to be at 25 mins.
After checking all the parameters in the new workbook the instructions below can be followed:
  • Ready Datastream- Are the red and green lights on?
  • Method Browser- This is the method for collecting the data. Click ‘method’, ‘new method’ and name the method. The next thing is to check ‘do data processing’.
  • Runlist- click ‘runlist’ and ‘add sample’. Type in the sample name for eg. ‘calibration A’, the batch name is left blank and the date will be inserted in there when processing occurs.
  • The filename will be the batchname plus 001, 002….
  • The sample type should read ‘narrow standard’ for for the calibration samples and then ‘unknown’ for the polymer samples.
  • The method should be data collection for all samples.
  • Calibration version should read ‘create’ as this will be set each time you perform analysis. The symbols ‘kappa’ and ‘alpha’ are used for the Mark Kewing correction, but we don’t need to alter/use these.
  • From here you go back to PCLGPC50, select the sample positions and start collection.
GPC Offline

This software is used to analyse the data collected using GPC Online.

First open the workbook the new data was collected to. (filename.plw is a workbook, filename.cgrm is a chromatogram)

  • Analysis runlist- pick and drag the runlist across, or you can double click the runlist. Then ‘generate method’.
  • Method Browser- name the folder you want to put your analysis into and check the ‘data processing’ box.
  • Column Calibration- Narrow standard, polynomial fit, of order (1). Calibrant automation, manual processing, manual peak analysis.
  • Sample Analysis- Automation should be set to ‘manual processing’ and detect peaks should be ‘auto’. The method used is called height approximation which splits up the peak into little segments and works out the area of the peak using the average height and width of the peak. Then adds up all segments for that peak.
Calibration should be done at least once per workbook. Analysis will not be possible otherwise.
  • Click on 'Method', then 'New Method'. Name the calibration method avoiding / and spaces
  • Go to 'Run List' (Right Hand Panel)
  • Import the two calibration chromatograms onto the run list
  • Set them to 'Narrow Standard' and select 'Create New' under method.
  • Go to 'Analysis' (Right Hand Panel)
  • If the calibration chromatogram is not shown click on the blue arrow to go the chromatogram
  • Apply peak detection (icon = graph with magnifying glass)
  • Delete peaks that are not required for calibration (icon = graph with X)
  • Click on Mw tap (above chromatogram)
  • Enter MW data (as shown on the calibration pack)
  • Add to calibration (icon = green graph)
  • Repeat this for the second calibration standard
Note that the calibration is not efficient if only one standard is used.
To obtain your GPC trace from the raw data:
  • Ensure that the required chromatograms have been imported onto the run list
  • Set the samples as “Unknown”
  • Go to Analysis (Right Hand Side panel)
  • Click on the blue arrow to go to next chromatogram
  • Apply peak detection (icon = graph with magnifying glass)
  • Delete peaks that are not required for calibration (icon = graph with X)
  • Click on the calculate icon
  • The Mw summary tab gives a table with your data
  • Reviewer (Right Hand Side panel) allows multiple plots to be superimposed on one another and printed
  • Raw data can be exported as text (ASCII) for use with other graphing software
Transferring Sample Names

There is a link between Cirrus and the instrument control software that will allow you to only have to enter the names once. When you set up the autosampler and hit the ´start sample injection´ option, a message comes up asking if your Cirrus Workbook is set up and ready for collection. At this point, the PL-GPC 50 software saves a file called ´autosample.rptl´ in the Cirrus Workbooks folder on your system. If you then go into Cirrus and click on the ´Collection Runlist´ view, under the File menu there is an option to load a runlist. Click on this and then select the .rptl file in the Cirrus Workbooks folder and the information will be loaded into Cirrus.It is worth remembering however that the autosampler sequence is not saved after the run is complete. if you want to mimimise the amount of data that is entered and the amount of saving and loading of files required, you could just enter the sample information into Cirrus and leave the table empty in the PL-GPC 50 software