Wyatt Technology Corporation - WyattQELS™ On-Line Quasi Elastic Light Scattering from your HPLC

The WyattQELS (Quasi-Elastic-Light-Scattering) instrument contains a real time digital correlator. The correlator measures the autocorrelation function of the intensity signal from any one angle of the DAWN or miniDAWN. The correlator then calculates the hydrodynamic radius at each elution time in order to provide hydrodynamic radii over an entire chromatographic peak.

Unlike any other dynamic light scattering instruments, the WyattQELS detector comes with the ability to measure correlation as a function of angle. Particles larger than 150nm may scatter relatively little light at 90 degrees because of intra-particle interface or "Mie scattering".

This effect may cause significant distortion in computer particles size distribution for some kinds of polydisperse samples. Since the WyattQELS optical fiber can be moved easily to any one of the DAWN or miniDAWN's angles, the measurements can be optimized for the best results for particles that are very large. With other instruments, which only make measurements at 90 degrees, if large particles are present, the signals may be low or lost altogether. But with the WyattQELS you can always move the optical fiber to a lower or a higher angle.

WyattQELS Features include:

• Multiple Tau correlation design with a fixed range of channel from 480 nsec to ~1 hour (real-time).
• No sample time optimization required!
• A total of 264 channels with input data format of 5 bit for the first 16 channels, the the sample time doubles every 8 channels and the data width is incremented 1 bit for every set of channels. No pre-scaling required.