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Raman spectroscopy tackles pharmaceutical raw materials: cost-effective, quick and handheld Raman spectroscopy devices are quickly becoming the tools of the trade for the quality control of pharmaceutical raw materials.

In recent years, Raman spectroscopy has gained a reputation in market segments that require the rapid identification of unknown compounds, such as the testing of high-purity chemicals, verification of pharmaceutical ingredients and the characterization of polymer materials. The surge of interest in Raman comes from modern instrumentation being equipped with intelligent decision-making software and onboard spectral libraries, which makes it an ideal technique for molecular fingerprinting purposes. Unlike traditional molecular spectroscopic techniques, Raman equipment can be used in a production environment or for field applications because it produces sharp, distinct peaks and requires virtually no sample pre-treatment or direct contact with the sample. Additionally, it has the unique capability of being able to test a sample directly through a transparent packing material like glass or plastic, with no impact on the spectral information.

Today's Raman instrumentation is faster, more rugged and less expensive, and advances in component miniaturization have led to the design of high-performance, portable, handheld devices. These handheld devices are particularly well-suited for pharmaceutical applications such as the testing of raw materials, verification of final products and the identification of counterfeit drugs because of the technique's extremely high molecular selectivity.

Principles of Raman

Similar to infrared (IR) absorption techniques, Raman spectroscopy measures vibrational, rotational and other low frequency modes of a molecule. While IR spectroscopy is based on focusing a broad range of IR wavelengths of light on to the sample and measuring which ones are absorbed, a Raman spectrum is obtained by directing a single wavelength of light and collecting the resulting scattered light. The frequencies of the scattered light depend on the bond strength of the molecules, the mass of the bound atoms and other factors, such as intermolecular interactions. The pattern of vibrational and rotational frequencies from a molecule is highly characteristic of a given molecular species or the structural arrangement of those molecules. Figure 1 shows Raman spectra of five similar molecules (top to bottom)--acetone, ethanol, dimethyl sulf-oxide, ethyl acetate and toluene, which are clearly differentiable, even to the untrained eye.

Testing of pharmaceutical products

Traditionally, the quality control of incoming pharmaceutical raw materials has either involved removing a sample from each lot of material received and running a battery of laboratory tests or using portable infrared equipment to carry out the testing of selected batches of the chemical ingredients. In addition, verification of the final pharmaceutical product requires far more stringent methods, and as a result, has traditionally been done by highly skilled analytical chemists who have to carry out extraction procedures and analyze the compounds using complex and time-consuming techniques like wet chemistry, liquid chromatography or mass spectroscopy.

Even though this approach has yielded satisfactory results, it is extremely slow, has not proven to be cost-effective and has created huge sampling bottlenecks, especially as the FDA is encouraging all drug companies to test every container of raw material that comes into their manufacturing facility. For this reason, over the years, analytical instrumentation companies have been working with the pharmaceutical industry to develop innovative solutions to replace current testing procedures, with the goal of increasing testing, while reducing overall costs.

There is no question that the technology that is proving itself to be the best fit for this type of work is Raman spectroscopy, which has the ability to rapidly determine whether the contents of a container of raw material or final pharmaceutical product are authentic based on comparisons to built-in or user-generated spectral libraries. And with the recent development of small, handheld devices, the technique can be used in any location of the manufacturing plant to provide the operator with an immediate answer to verify a material's chemical identity.

The rapid growth of Raman instruments for this type of analysis has been accelerated by a number of technological advances that make the technique ideally suited for the characterization of pharmaceutical raw materials. These advances include: state-of-the-an manufacturing procedures; innovations in optical designs; compact and highly stable detectors; much smaller electronic components; development of touchscreens; advances in computing capabilities; and longer and better battery performance.

These developments have led to the commercialization of compact, handheld Raman spectrometers and integrated computing systems for material identification and verification within cGMP-compliant facilities. Typically weighing 2 to 3 pounds, they allow rapid development of standardized and validated methods for identification and quality control applications. Confirmation of an unknown compound can be achieved in as quickly as 20 seconds, making it a practical choice for pharmaceutical material identification and verification purposes.

A recent commercial example of one of these handheld Raman systems is B&W Tek's NanoRam, which uses a spectrum-stabilized 785 nm wavelength laser excitation source and a temperature-controlled CCD detector to provide a stable signal with low background noise. Coupling this proprietary thermoelectric cooling with patented laser stabilization technology and a high-speed microprocessor, it provides laboratory-grade performance in a convenient handheld package. It has the capability to generate a signal with extremely high signal-to-background noise, which is required for the successful testing and confirmation of different pharmaceutical materials and products. A Raman spectrum of acetaminophen (Tylenol) using the Nanoram is shown in Figure 2.

Raman technology for the quality control of incoming raw materials is becoming the analytical tool of choice for the pharmaceutical industry. The reason for its widespread acceptance is that when it is applied to the rapid identification of chemicals in the warehouse, it is proving far more cost-effective than traditional central laboratory-based approaches. As a result, many manufacturing companies are finding that payback of the initial capital cost of the equipment can be achieved within 6 to 12 months.

CONTACT

For more information, please visit B&W Tek at www.bwtek.com, or call 302-368-7824.

RELATED ARTICLE: AT A GLANCE

* Modern Raman instrumentation is faster and more rugged.

* Handheld Raman devices allow rapid development of methods for ID and QC.

* Raman spectroscopy has been the analytical tool of choice for the pharma industry.

* Raman is proving to be more cost-effective than central lab-based approaches.

by Katherine Bakeev and Robert Thomas, B&W Tek, Newark, Del.
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Title Annotation:Feature
Author:Bakeev, Katherine; Thomas, Robert
Publication:Laboratory Equipment
Date:Mar 1, 2013
Words:1004
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