Analyzing Highly Fluorescing Cellulose-Based Excipients and Other Complex Molecules with a Novel 1030 nm Handheld Raman Analyzer

Dec 01, 2013

Handheld Raman analyzers have found widespread use in the pharmaceutical industry for excipients and raw materials verification, and in first responder/security applications. Most portable Raman units utilize lasers operating at 785 nm because of the relatively good signal strength at this wavelength.

Figure 1, 2: Raman spectra for material MCC Generic (top) and Croscarmellose (bottom) comparing a 785 nm laser and a 1030 nm laser. The Raman peak structure in both compounds is only evident when utilizing the 1030 nm laser.
There are many compounds that fluorescence strongly at 785 nm, causing a featureless background spectrum that obscures the telltale Raman signature. Compounds include the micro-crystalline cellulose (MCC) compounds used as excipients, and nutrients like Folic acid (vitamin B9). For security applications, Semtex and TNT precursors are good examples.

Figure 3: Raman spectrum from a common plastic explosive Semtex. The characteristic Raman peak structure is only evident when using the 1030 nm laser compared to the 785 nm.
SciAps has introduced a handheld Raman analyzer utilizing a novel 1030 nm laser source – SWIR Raman. The 1030 nm laser yields reduced fluorescence compared to 785 nm lasers. The 1030 nm laser is compatible with a proprietary Type III-IV sensor that requires less cooling than analyzers using 1064 nm laser sources. There are no cooling fans required, and smaller batteries may be used. Therefore a 1030 nm system is very portable, and is sealed to IP67 standards, making it dunkable and washable for quarantine or hotzone use.

One Example: MCC Generic and Croscarmellose

MCC is a particularly good example. MCC can be modified to different degrees of crystalinity usually in the range of 40 to 60%. Raman spectra from MCC generic and Croscarmellose, using the 785 nm laser (Inspector 300) and the 1030 nm laser (Inspector 500) are shown in Figures 1 and 2. The Raman peaks of the MCC and Croscarmellose clearly stand out at 1030 nm but are lost in the featureless fluorescence background at 785 nm. A similar benefit is shown for plastic explosive Semtex. Semtex is a combination of PETN and cyclonite (cyclotrimethylenetrinitramine) that contains complex double bonded N, C, and O structures that produce fluorescence at 785 nm laser wavelengths. As shown in Figure 3 this material is easily identified with a 1030 nm laser source.

SciAps, Inc.
2 Constitution Way, Woburn, MA 01801
tel. (339) 927-9455