Questions from our refractometer verification webinar

How to verify an inline process refractometer
Maria Nyman, Product engineer
Maria Nyman
Product Engineer
Life Science
Liquid Measurements

In December we held a brief webinar on how to perform a refractometer verification. We received questions we didn't have time to answer, so along with emailing our answers, we are sharing them in this blog. 

Question: What is the accuracy of refractive index measurements in the case of scattering medium?    

Maria Nyman: Liquid concentration measurement with an inline process refractometer measures selectively the liquid phase and dissolved solids. Sub-micrometer particles are also measured. However, the refractometer measurement and its accuracy are generally not impacted by the suspended particles in a scattering media, where the particles are typically well above a micrometer in diameter. However, the impact of scattering to accuracy is application specific. 

For more a detailed evaluation of your application, please contact us. For example, in a sugar crystallization application, where sugar crystals cause scattering and noise to the optical image, we have developed a specific algorithm that has excellent performance in the challenging application.

Question: Is the software available online?    

The verification itself is done by the refractometer system and depending on the refractometer model, the interface may be different. Every PR-43 series refractometer has a built-in web server with a homepage which allows you to configure, monitor, verify and diagnose the refractometer on a web browser.
Question: How long does it take to equilibrate the temperature of the refractometer?    

Maria Nyman: Reaching equilibrium depends on the verification location and the temperature differences. It is recommended to have the refractometer and verification liquids in the same room and thermal environment for about one day before performing verification procedure. The temperature of the refractometer can be monitored on the instrument interface, and it is recommended to wait until it is stabilized on a level that is between 20 °C and 30 °C.

Comment from attendee: Not a question but some feedback. It was a short webinar but very informative. I hope Vaisala continues offering these kinds of webinars in the future. Simple but effective. Thank you Vaisala!

Thank you to everyone who joined us!

You can view the recorded webinar here How to verify a Vaisala inline process refractometer

Blog: Perfecting solvent swap processes with refractive index trend data

Refractive index (RI) has proven to be a useful Process Analytical Technology (PAT) tool for the development, design, and continuous optimization of API manufacturing processes. Continuous, in-line measurement of RI provides data and process insight that aids in understanding and designing different manufacturing steps. The data allows for the creation of process profiles that can be used for detecting deviations and ensuring process equivalence. The Vaisala refractometer provides trend data with the high reliability and reproducibility required in pharma manufacturing. Refractive index measurements are not affected by the presence of gas bubbles, solid particles, or color of the liquid. These features of refractive index make it ideal for many applications in the API manufacturing process.  

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