Conventional calibration, universal calibration, and advanced or triple detection with light scattering can provide valuable but different characterization information for your samples. Find out more below!

Earlier this year we released the OMNISEC v11.20 software.  This latest iteration expands OMNISEC’s capabilities to include conventional and universal calibration analysis methods.  Since the data available from these methods based on calibration curves may seem similar to information from advanced detection (aka triple detection) analysis, the methods might seem the same…but they’re not! 

With different methods to choose from, it can be tough to know which one to use.  Fortunately, each method offers unique advantages depending on your situation.  The video and post below will provide information to help you decide when to use each analysis method. 

Advanced or Triple Detection (Light Scattering)

Advanced or Triple Detection should be your default analysis method.  You should use it whenever possible. It is the best way to get correct results for samples with unique or non-linear structures.  If you use a calibration curve method for these analyses the results can be dependent on how similar the structure of your standards is to the structure of your samples.  This leads to significant potential for error. In sum, Advanced or Triple Detection offers the most data with greater accuracy and less work than the alternatives!

Universal Calibration

Universal Calibration is often used in one of two situations:

  • Light scattering data is unavailable or unreliable
  • To upgrade from a single detector Conventional Calibration method

Light scattering data can be unreliable for a few reasons. The light scattering response could be weak due to the sample’s low molecular weight or its low dn/dc value.  Universal calibration can be used as an alternative as long as there is sufficient viscometer data.

Additionally, samples that fluoresce distort the light scattering response, typically in the positive direction.  If you’re working with a conjugated material and using light scattering to calculate molecular weight values that seem way too high, this could be the reason.  Universal Calibration serves as a nice alternative.

Depending on your sample, light scattering data can be unreliable. But if you have a viscometer, then Universal Calibration can still provide accurate molecular characterization data. Super cool!
Left: example of low light scattering response; Right: example of fluorescence producing high, off-scale light scattering response.

Conventional Calibration

While limited in its capabilities, Conventional Calibration can be a useful analysis method if you only have access to a single concentration detector.  It is also valuable if all you need are relative molecular weight values.  If you’re comparing samples of the same type, only interested in the samples’ distribution, have no need for structural information, or are looking for an economical method to analyze your samples, then Conventional Calibration can work for you.

Final thoughts

So, to recap: Advanced or Triple Detection with light scattering offers the most accurate results, and you should use it whenever possible!  Universal Calibration is a nice upgrade from Conventional Calibration and a convenient alternative when light scattering is unavailable.  And Conventional Calibration offers the least amount of data but is the most accessible analysis method and a great choice in the absence of light scattering and viscometer detectors.

If you have questions, please contact us or me individually at kyle.williams@malvernpanalytical.com. Let us help you make the best choice for you and your samples!

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