Some of you may be aware that the Zetasizer microV as well as the Zetasizer Nano ZSP can easily acquire molecular size data in flow. Here, ‘in flow’ means: continuously during a chromatography elution profile. So while in standard “batch” mode a cuvette is inserted and the software attempts to acquire the best achievable data by optimized settings. In automatic mode it optimizes settings behind the scenes, takes sub-runs, then averages those to achieve a final record. In flow mode on the other hand all emphasis is on speed of data acquisition, because an elution peak must not be lost, there is no time to dwell on acquiring the best data as the sample will have been gone otherwise.
Flow records in the Zetasizer software
When a Zetasizer is setup for flow data acquisition, just select the Flow Measurement type, determine the duration in volume [mL] or time [min], and the run duration [sec]. The run duration is the time over which the correlation function is accumulated. The flow rate in mL/min is found under the flow settings, along with the other typical data acquisition parameters (most can be left in automatic). Once setup, the system is ready to go, preferably after a sample injection is made into the 3rd party chromatography system.
After a run is finished, you may want to get access to the individual correlation functions with all their respective parameters. This is accomplished via a flow extraction macro to extract the desired relevant part of the flow record into a new file.
How to handle data extraction
If the flow macro was properly installed, just highlight the flow record, right-click – macros – chromatogram extractor set limits. A message box will ask for the desired target file name and the volume range to be exported into this file from start volume to end volume. The macro with the name Chromatogram Extractor-set limits will also include a new custom parameter that is the elution volume for each of the exported correlation functions.
How to install the flow macros
If the macros were not installed for some reason, you can download them in this paragraph. Right click on the links and save target as. The macros need to be saved with the file extension .zmac instead of txt. Once downloaded place the macro file into the folder C:\Program Files\Malvern Instruments\Zetasizer Software\Extras\Flow Mode\Macros or load the macro from within the Zetasizer software menu Tools – Options – Macros – Install new macros and navigate to the download folder.
- Chromatogram Extractor-set limits (right-click and Save taget as…)
- Chromatogram Extractor (right-click and Save taget as…)
Once installed the macros will then be available either by right-clicking on a flow record, or from the main Tools – Macros menu.
How to display a custom parameter
The macro places the elution volume into the Custom Parameter 1 field. In order to display this field in your workspace, edit your flow or size workspace (or even better yet, first export the flow space, import it again, but give it your own name, then edit this “own” workspace) by allowing size records and adding the custom parameter to the list.
It can be found under SOP Labels and the elution volume is the Custom Parameter 1. The displayed description can be changed by double-clicking on the field to change and to make it Elution volume [mL]. Please also see the FAQ Editing workspaces .
The simplest method to export a single distribution function is to display the distribution (for example the Intensity PSD) on the screen, then go to Edit – Copy Size Values , go to an open Excel spreadsheet and paste (Ctrl-V) the data into that file. This is available for many simple distributions [intensity, volume, number] and the raw correlation function. For other parammeters, create an export template, or utilize Excel export macros described in this zipfile Macros4export06Oct11 . Also see the FAQ Editing workspaces .
Macros in the above zip file collection include:
- Correlation data import, for the intensity auto correlation function
- Correlation Square Root ACF- Background, for the normalized field auto correlation function
- Export Intensities, for the Intensity weighted Particle Size Distribution
- Export Mobility distribution, for the distribution of electrophoretic mobility values
- Export Numbers, for the Number weighted Particle Size Distribution
- Export Volumes, for the volume weighted Particle Size Distribution
- Export Zeta Distribution, for the distribution of zeta potential values
- Export Zeta Phase Plot, for the raw phase plot from fast / slow field reversal
- Size Trend Data import, for the transfer of all highlighted size trend data
- Size Trend versus Temperature import, for the highlighted size values versus temperature
- Size Trend versus Time import, for the highlighted size data versus record creation time
Hope this helps you with extracting and transporting data from your Zetasizer into other applications.
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