The Viscosizer 200 is now here!

par Malvern Panalytical, Thursday, 1st August 2013

Yesterday we launched the Viscosizer 200, which is an innovation in automated viscosity measurement and molecular sizing using very small sample volumes. This new technology is driven by UV area imaging, and at its heart is a unique dual-pass capillary system, with two detection windows removing any injection time error. This instrument is ideally placed to serve those working within biopharmaceutical preformulation and formulation development, who need rapid viscosity information on a large number of low volume samples.

View the launch presentation of the Viscosizer 200:

Thanks for all those who attended our launch event, and we hope you enjoyed it. The application notes we discussed are all now available on the website and can be found by visiting the Viscosizer homepage:

http://www.malvern.com/viscosizer200

Your questions made for an interesting discussion afterwards. We are sorry that we didn’t manage to answer everyone’s questions at the end so we thought we would write them down and publish them in our blog for all to see. Have a look through them and if you have any more questions, please don’t hesitate to get in contact with us. We will be updating this Q&A as and when we receive new questions.

Question	Answer
I have protein and RNA in sample, not one protein only. Can it do (Viscosity and Rh)?	Yes, the Viscosizer 200 can certainly look at the total formulation viscosity and give a mass-weighted average size. The experiment could perhaps be altered to look at the RNA and protein separately in the same buffer to give some idea of the contribution each would make to the overall viscosity and average size, if this is what is required, but of course the combination of the two types of molecule could influence the overall parameters.
What is the concentration range of the instrument?	We have comprehensively tested the Viscosizer 200 on protein samples with concentrations ranging from 0.1 mg/mL to 300 mg/mL, and as a result, this is the range we have listed in the product’s specification. However, the instrument is more than capable of measuring well outside this range. We are continuing to test how far we can push the instrument and will report back on this.
I saw on the specification list that the range of viscosities measurable is 0.9 – 120 cP, but then you showed some data for a 230 cP measurement – which one of these is accurate?	From our internal testing, we have confidence in the range 0.9 – 120 cP, which is why it is listed in the product specification, but the instrument can be pushed harder and will analyse much higher viscosities if required. One consideration we make is the length of time it takes to perform a measurement is very important, as obviously the more viscous a sample is, the longer it takes to push through the microcapillary and make a measurement . Most samples can be analyzed in 15-20 minutes, but some really viscous samples may take a while longer.
Is there a temperature control in the system?	Yes, the system is temperature controlled in two areas – the oven, and the carousel. This temperature control will hold the system at ambient temperature throughout, ± 2°C. The system has been tested at ambient temperatures of 16°C to 30°C to cover the typical range of lab temperatures. Good temperature control is obviously very important for the measurements that the Viscosizer 200 makes.
Does the instrument need calibration? Does it need lot maintenance?	For size measurements, no user calibration is required, although the internal diameter of the capillary in use must be known. Viscosity measurements are made relative to a known reference sample. In terms of maintenance, it is good practice to rinse the capillaries with water at the end of every schedule of measurements in order that they are kept in good condition. We also recommend a yearly service for the instrument, and 6 monthly replacement of pressure seals.
Are there any applications notes?	Yes, there are currently two application notes, one to cover viscosity and another to cover sizing in the presence of large molecules, on the Malvern website, along with a product brochure. There is also a lot of information on the technology and how it works to be found in the same place. The best place to start looking is at malvern.com/viscosizer200
How much rinse solvent is needed? Are the vials before analysis heated or possible cooled?	How much rinse solvent is required really does depend on the type of sample which has previously been analysed. Obviously, very sticky or viscous samples will require a longer capillary rinse. Our general rule of thumb is that a standard rinse should use at least twice the capillary volume in water, and for a very sticky sample, up 10 – 15X capillary volume in water should be applied. The maximum volume of one of our larger vials, which would hold the rinse solution (water) is 4 mL, so this should give an indication of the absolute upper limit for rinsing. Vials can be heated and cooled in the autosampler, between 16°C and 30°C.
Is it possible to make sizing and viscosity measurements simultaneously?	No, this is not currently possible – each meaurement, whether it’s a sizing or a viscosity measurement needs to be performed on a separate injection of sample. It is obviously possibly to program measurements of both types into a run schedule, so one can be run in an automated fashion one after another.
Has Malvern introduced automated software for viscosity analysis? Early this year, we had it installed and it was a little tedious using the manual software	Yes, we now have fully automated Malvern software for both size and viscosity analyses. This software controls the entire process of the analysis, from introduction of samples, to scheduling a run and batch analysis, through to data analysis and report generation. The software will even define the length of the viscosity measurement, so that the correct volume of sample is analyzed, and no sample is wasted.
Is there a value obtained by the Viscotec similar to the %PD by DLS to indicate the presence of multiple species with <3X differences in size?	The Viscosizer 200 currently measures size of molecules/particles by giving a mass-weighted average result, so the result for a polydisperse system would be an average size. However, trends occurring in such a sample could be monitored by the instrument. UV selectivity could also be used to give a measurements of individual elements within a complex system.
What kind of software is used for evaluation?	A single and intuitive Malvern software application controls all sample introduction, methods, analysis and reporting.
What is the temperature range of the unit?	The system is temperature controlled in two areas – the oven, and the carousel. This temperature control will hold the system at ambient temperature throughout, ± 2C. The system has been tested at ambient temperatures of 16°C to 30°C to cover the typical range of lab temperatures. Good temperature control is obviously very important for the measurements that the Viscosizer 200 makes.
How does the instrument handle polydisperse systems?	The Viscosizer 200 currently measures size of molecules/particles by giving a mass-weighted average result, so the result for a polydisperse system would be an average size. However, trends occurring in such a sample could be monitored by the instrument. UV selectivity could also be used to give a measurements of individual elements within a complex system.
Congrats for the great presentation! Do you see any kind of application for cosmetics (emulsion) characterization?	Thank you very much! Yes, we can see a variety of applications in emulsion characterization. Potentially the Viscosizer 200 could be utilized to provide viscosity/shear thinning characteristics for cosmetics in a high throughput way. The shear rates achieved between 100-2000 S-1 are relevant for dispensing from bottle, initial spreading on skin etc.