PAT in the Chemical Industry: The Effectiveness of Analyzers

For those who have never worked in the pharmaceutical industry, the term PAT (process analytical technology) may be unfamiliar. It describes an effort between pharmaceutical manufacturers and the FDA, started some 20 years ago, to establish procedures so those companies could have greater flexibility when making changes to validated production processes. Rather than simply following a fixed recipe and testing at the end to make sure the product was on-spec, producers were able to use analyzer technologies at strategic points during the run to see if adjustments were necessary.

One of the arguments suggested by pharma producers in favor of PAT was essentially, “This is how conventional chemical companies do things. We could benefit from the same approach and avoid a lot of rejected batches.” The FDA agreed and it allowed major improvements to the industry. Now, those conventional chemical companies are seeing the value in new ways. How this is happening is the main subject of my article in the July/August issue of PI, Applying process analytical technologies in the chemical processing industry (

One of the main elements of PAT in the chemical industry is its use to monitor a process so it can be optimized while the process can still be adjusted, rather than sticking with fixed parameters throughout a long production run. Since there may not be a sensor to quantify a specific attribute of the process, such as verifying that a reaction is complete by monitoring the concentration of a product, common generic measurements must serve as indicators. These often include conductivity, pH, and dissolved oxygen.

To be on-spec, complex products will usually call for a variety of specific attributes, and quantifying these often requires the types of liquid analyzers just mentioned.

So, what are some of the products in the Rosemount catalog designed for these tasks?

  • The Rosemount 242 Flow-Through Toroidal Conductivity Sensor is a useful way to quantify the presence of conductive ions in a solution, which can be used to measure acidity or alkalinity. It also determines total dissolved solids.
  • The Rosemount RBI pH/ORP Sensor is a premium pH sensor for a wide variety of applications. For example, it is frequently used in oil refining to determine the presence of sulfides in feedstocks, or in chlor-alkali processes for pH control at critical steps.
  • The Rosemount 499ADO Dissolved Oxygen Sensor is often used to monitor aeration basins in wastewater treatment processes, but also in other areas, such as oxygen control in fermentation tanks for ethanol production.

But the sensors are only part of the picture. Plant personnel must understand what the numbers mean and make use of the data. The Rosemount 56 Dual Channel Transmitter allows users to access troubleshooting guidance or simple technical explanations with respect to any reading or alert with the push of a button. The transmitter also allows users to directly download measurement and other data so they can analyze it in their preferred tool.

Accurate and reliable liquid analysis measurements, following PAT concepts, are critical in a wide range of chemical processing facilities to protect capital assets, ensure product quality, increase process uptime, and reduce energy costs. These measurements are now more widely available in real-time due to advances in online analyzers, allowing chemical plants to close control loops quickly, instead of relying on outdated data from lab instruments.

For more information, please visit the Liquid Analysis pages at You can also connect and interact with other engineers in the Chemical Processing Groups at the Emerson Exchange 365 community.

Process Instrumentation Jul/Aug 2022, Applying Process Analytical Technologies in the Chemical Processing Industries, by Charu Pandey

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