Wyatt Technology

WyattQELS DLS Module

WyattQELS

The WyattQELS module adds dynamic light scattering (DLS) capabilities to a DAWN, miniDAWN or μDAWN MALS detector.

DLS determines the sizes of macromolecules and nanoparticles as Rh, the hydrodynamic radius, calculated from the diffusion coefficient. 

The combination of DLS and MALS helps assess particle shape and conformation by comparing the hydrodynamic radius to either molecular weight or rms radius.

An alternative to the WyattQELS for online DLS operation is coupling a DynaPro NanoStar or Möbiuζ to a MALS instrument's optical system by means of the DLS Compatibility Kit fiber optic.

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  • MALS and more

    A WyattQELS module integrates directly into the MALS detector to measure Rh in the same flow cell and detection volume as MALS, enjoying the same laser and optical quality. Combining these two light scattering technologies in the same physical detection cell assures perfect coincidence between the two types of measurements, for accurate conformational analysis. Extend the capabilities of your MALS detector to address even more analytical challenges for macromolecules and nanoparticles.

    Benefits of WyattQELS

    Each WyattQELS contains a real time digital correlator to measure the autocorrelation function of the intensity signal from any one angle of the DAWN HELEOS II or from the 90° location of the miniDAWN TREOS. In a SEC-MALS measurement, ASTRA transforms the autocorrelation function at each elution time in order to provide Rh over an entire chromatographic peak. In a batch measurement, ASTRA or DYNAMICS can calculate an average Rh or even a size distribution covering 3 orders of magnitude.

    Unlike many other DLS instruments, the WyattQELS detector, when interfaced to the DAWN or miniDAWN, can measure DLS at selectable angles. Angle selectivity is helpful in optimizing analysis of different size ranges.

  • WyattQELS features include:

    • Multi-tau correlation design with a fixed range of channel from 100 nsec to ~1 hour (real-time).
    • No sample time optimization required!
    • A total of 512 channels with input data format of 5 bit for the first 16 channels; the sample time doubles every 8 channels and the data width is incremented 1 bit for every set of channels. No pre-scaling required.
  • Adding on-line DLS size measurements

    Incorporated into the DAWN, the WyattQELS can be installed at any of the 18 scattering angles supported by the read head, optimizing measurements of hydrodynamic radius and complete size distributions upon separation by SEC/GPC or Eclipse-based FFF.

    For on-line measurements, this feature adds enormous flexibility to the size range of molecules that may be studied. While MALS can readily measure molar masses down to a few hundred Da, it is limited to a lower size limit of about 10 nm; the WyattQELS extends the size range down to 1 nm, allowing aggregation phenomena and conformation to be studied with greater precision than ever before.

    The DAWN HELEOS II can be ordered with precise temperature control capabilities with its on-board Peltier heating/cooling accessory. This feature is particularly useful for QELS measurements, since studies can be performed to examine particle sizes as a function of temperature.

    Incorporated into the miniDAWN TREOS, the WyattQELS can only be installed at 90°. This is sufficient for most proteins and other macromolecules of moderate size, up to 40 nm in hydrodynamic radius (comparable to the limit on MALS measurements of rg).

  • Sometimes, off-line is the way to go

    The size range accessible to DLS increases greatly when flow is not present. Incorporated into the DAWN, the WyattQELS can be installed at any of the 18 scattering angles supported by the read head, in order to optimize batch measurements of mixed nanoparticle sizes.

    Among other applications, batch DLS is very useful in examining rates of aggregation or dissociation, when the time scales are on the order of a minute or longer (limited primarily by the time it takes to mix a sample and place it in the detector). It also excels at analyzing conformation as a function of temperature and solution properties.

    Batch measurements may be performed by injecting sample into the flow cell ("microbatch") or by replacing the flow cell with a scintillation vial. The number and range of useful angles varies with the sample cell geometry.

    DAWN or miniDAWN?

    The DAWN HELEOS II can be ordered with precise temperature control capabilities with its on-board Peltier heating/cooling accessory. This feature is particularly useful for QELS measurements, where studies may examine particle sizes as a function of temperature.

    Incorporated into the miniDAWN TREOS, the WyattQELS module can only be installed at 90°. This limits somewhat the ability to measure complex samples with both soluble and colloidal components.

    The WyattQELS may also be used in a DAWN or miniDAWN in batch mode with special 10 µL cuvettes. Even using such small volumes, simultaneous measurements of molar mass are always available.

  • Size Range (Radius)
       Flow Mode 1 – 300 nm with DAWN HELEOS II, 1 - 40 nm with miniDAWN TREOS (upper limit depends on flow rate and scattering) *
       Batch Mode 0.5 nm – 1 µm
    Fluidics
       Minimum Sample Volume (batch) 10 µL (microcuvette) to 200 µL (flow injection)
    Data Acquisition 0.1 – 3600 seconds
    Correlator Minimum Delay Time 100 nsec
    Hardware Interface 512 channel digital autocorrelator with multi-tau distribution
    Maximum Light Intensity 30,000,000 photons per second

    * The WyattQELS unit is installed internally in a DAWN or miniDAWN instrument.


    Facilities requirements may be found in Wyatt Instrument Facilities Specifications.
    Host PC requirements may be found in Computer Requirements.

    Specifications subject to change without notice.

   

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Wyatt Technology is the recognized leader in light scattering instrumentation and software for determining the absolute molar mass, size, charge and interactions of macromolecules and nanoparticles in solution.

Wyatt's line of multi-angle static light scattering products couple to size exclusion chromatography (SEC-MALS), field-flow fractionation (FFF-MALS), and stop-flow composition-gradient systems (CG-MALS). Our dynamic light scattering (DLS) products operate in traditional cuvette as well as on-line and automated, high-throughput modes. We also offer unique instruments for electrophoretic light scattering (MP-PALS), differential refractometry, and differential viscosity.



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