WyattQELS DLS Module

The WyattQELS module adds dynamic light scattering (DLS) capabilities to a DAWN®, miniDAWN® or microDAWN™ detector.

DLS determines the sizes of macromolecules and nanoparticles as R_h, 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.

In the DAWN (NEON), the optical fiber may be located in one of four angular positions, at 50.5°, 90°, 135° or 150°, in order to optimize batch measurements of mixed nanoparticle sizes. ASTRA software automatically detects the occupied position. In the DAWN HELEOS, the WyattQELS can be installed at any of the 18 scattering angles supported by the read head.

The miniDAWN provides a fiber mount at 135° scattering angle and the microDAWN fiber mount is at 130°.

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

Download our Application Note

If you are a current US or Canadian Wyatt Technology customer, you can purchase the WyattQELS online. Visit the Wyatt Technology Store today!

Product Description
Advanced Technology
On-Line
Batch Operation
Specifications

MALS and more

A WyattQELS module integrates directly into the MALS detector to measure R_h 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 or from the 90° location of the miniDAWN. In a SEC-MALS measurement, ASTRA transforms the autocorrelation function at each elution time in order to provide R_h over an entire chromatographic peak. In a batch measurement, ASTRA or DYNAMICS can calculate an average R_h 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 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, 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 r_g).
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 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 to 300 nm with DAWN, 1 to 40 nm with miniDAWN (upper limit depends on flow rate and scattering) *
Batch Mode	0.5 nm to 1 µm
Fluidics
Minimum Sample Volume (batch)	10 µL (microcuvette) to 200 µL (flow injection)
Data Acquisition	0.1 to 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.

Host PC requirements may be found in Computer Requirements.

Specifications subject to change without notice.

WyattQELS DLS Module

MALS and more

Benefits of WyattQELS

WyattQELS features include:

Adding on-line DLS size measurements

Sometimes, off-line is the way to go

DAWN or miniDAWN?