microViscoStar^™

   Online differential viscometer for UHPLC 

 

Highly Sensitive

A highly sensitive, on-line differential viscometer used with SEC-MALS-IV to determine the size and conformation of polymers, proteins and peptides separated by UHPLC.

---

Multiple Novel Technologies

The microViscoStar^™ incorporates multiple novel technologies to provide the highest sensitivity, stability and solvent compatibility of any available viscometer for UHPLC. Its ease-of-use and serviceability make it the perfect companion for Wyatt's microDAWN^™ light scattering and microOptilab^™ refractive index detectors for UHPLC.

---

APC and UHPLC Applications

View the webinar Development of a New Online Micro-Viscometer for APC and UHPLC Applications.

To learn about the technological breakthroughs implemented in the microViscoStar, download ViscoStar: Innovations in Online Viscometry for GPC.

 

 

Differential Viscosity
Sensitivity (minimum detectable sample)	5 ng of 100 kDa polystyrene in THF at 1 mL/min, under typical UHPLC-SEC conditions
Differential pressure noise	< 0.05 Pa
Differential pressure range	6.9 kPa, protected against overpressure
Dynamic range	135,000:1
Linearity	0.5% of full scale
Differential pressure drift	< 1.25 Pa/hr
Capillary bridge autobalance	Thermal, leak-free mechanism
Sample shear rate	15000 Hz with water at 1 mL/min
Fluidics
Max. flow rate	Aqueous: 1 mL/min; THF: 1 mL/min1
Delay volume options	5.4 mL
Max. permissible pressure inlet to outlet	3000 kPa (435 psi)
Wetted Materials	316 stainless steel, PTFE, zirconium silicate, Kalrez®, Inconel, 26-1 Stainless Steel, Nickel2
Temperature Control
Range	4 °C to 70 °C
Stability	<0.005°C
Ambient Range	0 ºC to 40 ºC, 20% to 70% RH
Electronics
Digital Output	20 bits @ 10 Hz
Auxiliary I/O
Inputs	Autoinject contact closure, Alarm In, Analog In: 2 differential inputs, 16 bits resolution, range -10 V to +10 V
Outputs	Autoinject Retransmit, Alarm Out, Recycle Out
On-board Computer
Communications	Ethernet
Front Panel Display	7" (178 mm), high-resolution, multi-touch display for viewing/setting signals, instrument settings and diagnostics.
Dimensions	60 cm (L) x 36 cm (W) x 17 cm (H)

¹ Addition of an inline UV detector may impose a lower maximum flow rate.

² Due to the location of the wetted materials on the microViscoStar detector, it is suspectable to corrosion when using buffers with high ionic strength. It is primarily recommended for use with organic solvents.

 

 

Another path to polymer and protein characterization: SEC-MALS-IV

When coupled with UHPLC size-exclusion chromatography and a compatible concentration detector such as the Optilab^™, 

the microViscoStar derives the intrinsic viscosity (IV) of polymers, rapidly and with minimal sample and solvent consumption. 

An inherently valuable physico-chemical property in itself, IV is best utilized together with molar mass information from a microDAWN multi-angle light scattering (SEC-MALS-IV)

to derive the hydrodynamic radius, conformation, and branching ratio of a macromolecule in solution.

Key benefits of the microViscoStar

• High sensitivity, equivalent to 5 ng of 100 kDa polystyrene in THF at 1.0 mL/min injected onto a standard GPC column

• High dynamic range of over 135,000:1. The full measurement range corresponds to over 13 mg/mL of 100 kDa polystyrene in THF

• Extended solvent compatibility with all-316 stainless steel transducers

• Temperature range from 4 °C to 70 °C for polymers or proteins that require a range of temperatures

• Minimal band broadening thanks to fast pressure transducers

• Pump pulse suppression to below 4 Pa (hardware alone) or 1 Pa (hardware + software) without loss of chromatographic resolution

• Automated capillary bridge tuning with no moving parts, to guarantee a perfectly balanced bridge, every run

• Enhanced thermal stability with drift of <1.25 Pa/hour

• Strongly fluorescent polymers

• Weakly-scattering polymer/solvent systems with very low dn/dc values

 

SEC-IV without MALS?

Yes, as much as we love MALS for optimal polymer analysis, it's true that there are occasions when it just won't fit the bill.

Universal calibration is a parallel technique to SEC-MALS for determining molecular weight, commonly used to characterize linear polymers. While universal calibration overcomes some of the problematic issues associated with column calibration by reference molecules, it does not account for non-ideal column behavior caused by chemical solute-column interactions or hyperbranching.

Universal calibration is particularly-well suited to replace MALS for:

The Mark-Houwink-Sakurada relationship makes use of empirical relationships between intrinsic viscosity and molar mass, specific to each polymer and solvent, to estimate molar mass from SEC-IV measurements. Of course, the best way to determine MHS coefficients is to measure them using SEC-MALS-IV and ASTRA!

Go to the Advanced Technology tab to learn more about the unique features of the microViscoStar.

 

 

Patented pulse compensation technology in the microViscoStar eliminates pump fluctuations. At the hardware level, the bridge is impedance-matched for dynamic balance, greatly reducing the effect of pump pulses. An additional layer of software filtering eliminates residual pump pulses.