How can I validate the performances of DLS and ELS instruments?

Introduction

Periodic system validation, demonstrating that your instruments are measuring properly, increases confidence in measured results and is essential to any scientific endeavor. Particle standards are used to validate the suitability and optimum performance of particle size and concentration analysis with DynaPro^™ NanoStar^™ and Plate Reader instruments, as well as size and mobility/zeta potential determination with DynaPro^™ ZetaStar^™ or Mobius^™ ELS/DLS instruments. Wyatt offers certified particle standards for DLS and ELS measurements, consisting of suspensions of nanoparticles with specific sizes and concentrations, and particles with known electrophoretic mobility.

Figure 1. DynaProNanoStar II and Plate Reader, Mobius. Click to enlarge image.

Particle size and concentration standards

These standards contain highly uniform polystyrene latex particles that are available with radii of 50 nm and 150 nm, suspended in 10 mM phosphate buffer at pH 7.2. The concentrations, optimized for ease of dispersion and colloidal stability, are ~2×10¹⁰ particles/mL for 50 nm size standards and ~1×10⁸ particles/mL for 150 nm standards. They are packaged as aqueous suspension in 15 mL dropper-tipped bottles and are ready for use without further dilution. The packages are lot certified and compatible with all DynaPro NanoStar, DynaPro Plate Reader and Mobius products.

Figure 2. The size distribution of individual PSL size standards, indicating essentially monodisperse peaks with low polydispersity.

Mobility standard

The lot-certified electrophoretic mobility standard, for use with a Mobius, contains highly uniform polystyrene latex particles of 150 nm nominal radius that are suspended in 10 mM phosphate buffer at pH 7.2. The concentration is optimized at ~3×10⁹ particles/mL for colloidal stability and ease of dispersion. The mobility standard is packaged as aqueous suspension in 15 mL dropper-tipped bottles and ready for use without further dilution.

Figure 3. An example of certificate of analysis for mobility standards.

Purchasing standards and obtaining Certificates of Analysis

Wyatt’s certified size and mobility standards help ensure that your DLS and/or ELS instruments are performing to specification. They may be purchased on the Wyatt Technology Store:

Lot-certified, 50 nm radius nanoparticle size standards: https://store.wyatt.com/shop/nanostar/nanostar-1/50-nm-radius-batch-dls-size-standard-lot-certified/
Lot-certified, 150 nm radius nanoparticle size standards: https://store.wyatt.com/shop/nanostar/nanostar-1/150-nm-radius-batch-dls-size-standard-lot-certified/
Lot-certified electrophoretic mobility standards: https://store.wyatt.com/shop/mobius/mobius-mobility-standard-lot-certified/

Lot-certified standards for other Wyatt instruments, such as RI standards, 30 KDa and 200 KDa polystyrene, BSA ampoules and 40 KDa dextran, are available under the “Validation Standards” tab. All Certificates of Analysis are digitally available on the Wyatt web store under the “Certificates of Analysis” tab.

Figure 4. Validation standards available on the Wyatt Technology Store.

Figure 5. Certificates of analysis page for DLS size standards and electrophoretic mobility standards available on the Wyatt Technology Store.

Conclusion

Do you have a question? Contact our experts here in Customer Support. We’re happy to help! Call +1 (805) 681-9009 option 4 or email support@wyatt.com.