IR for the Masses

Algorithms are making more applications, particularly in NIR, easier for non-spectroscopists to use; PerkinElmer’s Sharon Williams shares insights.

After returning from the Eastern Analytical Symposium (EAS), where PerkinElmer (PKI) introduced a number of new products, the company’s infrared (IR) business manager Sharon Williams discussed her views on IR and where it is going in pharmaceutical applications of process analytical technology (PAT), and talked about some of her company’s new technologies.

P.M.: What was the highlight of this year’s EAS?

S.W.: The key message I took from the Eastern Analytical Symposium is the fact that the drug industry’s adoption of PAT is starting to accelerate, particularly its demand for NIR and chemical imaging technologies. This adoption has been talked about for several years now, but we are finally starting to see it happen. NIR is becoming particularly important for raw materials testing, as the industry is learning that raw material quality problems all too often translate, down the line, into batch failures.

P.M.: What new technologies did PerkinElmer introduce at the Symposium?

S.W.: We introduced two new FT-IR and FT-NIR spectrometers, the Spectrum 100 and 100N, which include a number of features, including:
  • an improved Universal Attenuated Total Reflectance (UATR) accessory, designed to help simplify measurement of solid samples and to minimize variations in measurements, between different users and different samples;

  • a new fiber optic NIR probe with a user interface; and

  • enhanced versions of Spectrum and AssureID software packages.
P.M.: What’s significant about the new UATR accessory?

S.W.: UATR measures changes that occur in an internally reflected infrared beam when that beam comes into contact with a sample through an optically dense crystal. In older designs, the sample plate was clamped against the vertical face of the crystal. As a result, the beam couldn’t always sufficiently penetrate fine powder samples, resulting in weak spectra, particularly at short wavelengths.

Improved designs have placed the crystal parallel to the sample plate, so that there are between five and 10 reflections at each surface of the crystal. These newer models also used diamond as the crystal, minimizing maintenance requirements.

However, in the new Universal Attenuated Total Reflectance (UATR) accessory, PerkinElmer further improved the design of the moveable arm used to clamp the sample in place. It has been designed so that users feel a “click” when the plate is placed in the ideal location. It’s also designed so that it swings out of the way for cleaning and crystal maintenance.

In addition, the top plate is now kinetically mounted. This means that the sample will be centered in the exact same position every time you run a sample -- the kinetic mounts and the arm improvements are what generate the enhanced reproducibility.

P.M.: And what is so special about the NIR probe? Haven’t such things been around for years?

S.W.: What makes this probe particularly notable is the fact that it comes with its own user interface, incorporating a design intended to make it much easier to use on the manufacturing plant floor. Since the drug industry is becoming more interested in applying NIR to assure raw material quality, PKI felt that it was important to make the device easier to use. It’s designed to allow users to record measurements at considerable distances, up to 10 meters, from the instrument and PC interface, making it more practical to apply NIR on the plant floor.

In the past, operators had to take the measurement, then walk back to their PCs to record those measurements. Now, at his or her PC, a technician can press a “Go” Button that connects them directly to the instrument, allowing them to start or stop a scan without having to use the PC interface.

The user can then walk over to the batch testing area, where raw material batches have previously been set up for testing, simply take the probe, dip it into raw material — say, an incoming excipient, and learn immediately (via a “green” or “red” display) whether material has met for failed to meet specifications. Readings are automatically fed into the computer system.

P.M.: What have been the most significant recent breakthroughs in IR spectroscopy?

S.W.: Algorithms have advanced tremendously, minimizing variations in measurements and making the devices much easier to use. Twenty, even 10 years ago, the only way to compare actual vs. ideal spectra was to look at them. Today, IR instruments are sensitive enough so that results are reproducible and consistent, between instruments and technicians, at locations around the world.

At PerkinElmer, algorithms such as the Atmospheric Vapor Compensation (AVC) system have contributed to measurement consistency by removing the signal interferences caused by water and carbon dioxide.

In 1998, PKI launched an Absolute Virtual Instrument (AVI) algorithm to eliminate the traditional “master/slave” approach, in which instrument readings were based on readings from one “master” instrument using a standard spectrum. Because readings on the master instrument could, and often did, vary over time, and because calibrating the master device typically required a very skilled engineer, the approach led to less than optimal results.

With the AVI, each instrument becomes in effect a master instrument, but readings are compared with a synthetic reference spectrum calculated using high-resolution values for methane, supplied by branches of the U.S. military. Using this system, users compare all measurements against this “ideal” spectrum. This technology is particularly useful for global companies with numerous facilities in different countries, as it provides a universal standard.

P.M.: Are you working with any PAT modeling software suppliers on specific pharma PAT solutions?

S.W.: Not at this point, although we provide basic chemometric analysis capabilities with our instruments for lab applications, and users can export data from our instruments in Infometric’s (Woodinvale, Wash.) Pirouette file formats. But it’s an area that we will continue to devote more attention to.

P.M.: Have you expanded your pharmaceutical industry outreach and training efforts?

S.W.: We will introduce FT-IR and FT-NIR educational online seminars during the first half of 2006. Our major focus, though, will be on continuing to make our IR spectroscopy products inherently more robust and easier to use.

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