Analyze this!

Measurement and control of physical properties such as level and flow are the heart of process control. But measurement and control of the molecular composition of a process stream are also of vital importance.

By Dan Hebert

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Glanbia had to overcome a general skepticism in the dairy industry that process analyzers could survive in an environment with high levels of fats and calcium, known to render ineffective even simpler devices such as flow meters.

Ryan concludes, “The food processing industry does not have the internal maintenance support structure of analyzer technicians more commonly available in heavier industries such as refineries and chemical plants. This was overcome because the analyzers operate without requiring regular and frequent internal maintenance support. We just have the analyzers serviced on a contract basis every six months by an outside supplier, and this is sufficient to yield an uptime of better than 99%.”

More Durable PH Sensors Save Millions


  pH Sensor

Rob Pastushak, senior technical/operational supervisor at Gilead Sciences’ Alberta, Canada, facility inspects a pH sensor.

Gilead Sciences is an international biopharmaceutical company headquartered in Foster City, Calif., that discovers, develops and commercializes innovative therapeutics. “The compounds we produce are used in various human applications from cancer treatments to anti-virals,” says Rob Pastushak, senior technical/operational supervisor at Gilead Sciences’ Alberta, Canada, facility.

To assure consistent product quality and maximize batch yields, the Alberta facility needed to improve pH measurement. “Our pH sensors could not hold up under the aggressive chemicals that we use such as hydrobromic acid. The organic solvent constituent caused the probe’s O-rings to degrade during the most critical point of the process. In many cases, three $600 probes would fail during just one batch,” says Pastushak.

Once the O-ring degraded, the pH probes no longer provided accurate readings, which presented another problem for Gilead. The process calls for two phases of crystallization, each of which requires pH measurement with tight tolerances. “Crystallization is critical, and pH is king. When the chemical composition of a drug falls outside of the correct pH range, quality and yield suffer because maximum crystallization fails to occur,” explains Pastushak.

Because of the unreliability of these devices, Gilead was forced to confirm pH measurements on a bench-top meter in the lab. “When you process 3,000 to 5,000 liters and add 5 to 10 kilos of caustic solution at a time, it might take 20 to 40 lab tests to ensure the pH is right,” continues Pastushak. “Going to the lab so often to confirm pH just killed production efficiency.”

To resolve the pH measurement issue, Pastushak researched several probes and decided to test a Foxboro 871PH sensor from the measurements and instruments division of Invensys Process Systems. “We found many vendors that offered quality sensors, but the Foxboro sensor’s polymer plastic construction was the only one that could stand up to all the reagents and solvents in our solutions. Foxboro also modified the sensors to include O-rings made out of Kalrez, a big factor in us choosing them over their competitors,” says Pastushak.

“We can now complete a pH adjustment in three hours rather than the 18 to 24 hours,” says Pastushak. “And we no longer have to take 40 samples to the lab to confirm accuracy—just one as a matter of quality-assurance protocol. Every time we grabbed a lab sample, we had to put the process on hold until we got the results back. This is significant when you consider not only the yield impact, but the cost of a process hour,” according to Pastushak. Reducing the number of confirmation measurements also improved personnel safety because technicians need to open the line to manually obtain samples.

Eliminating 40 grab samples allows Gilead to produce more batches in the same period of time. Online analysis has helped reduce manufacturing cycles by up to 20%. “Overall, yields have increased and cycle times have been shortened. When you add in the increase in quality, the improved pH readings by one sensor can be worth hundreds of thousands of dollars per year,” concludes Pastushak.

CLICK HERE to open an Excel Spreadsheet that illustrates the Glanbia Process Flow Representation.

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