NIR imaging

NIR images are taken exclusively in reflection geometry. Therefore, the method is mainly surface-sensitive with a limited penetration depth. 

References [52-54] do not include any data directly comparing squaraine rotaxanes with common cyanine dyes such as Cy5 (GE Healthcare) and Alexa 647 (Life Technologies). Nevertheless, from the available data it can be concluded that squaraine rotaxanes are remarkably resistant to chemical and photochemical degradation, and likely to be very useful as a versatile fluorescent scaffold for constructing various types of highly stable, red and near infrared (NIR) imaging probes and labels. 

Evolution of NIR Imaging Instrumentation 8.3.1 Spatially resolved spectroscopy - mapping... 

FIGURE 5 Acquisition by LCTF NIR imaging system. (Adapted from N. Lewis, J. Schoppelrei, E. Lee, and L. Kidder, in Process Analytical Technology, Editor K. A. Bakeev Blackwell, London., 2005, pp. 187-225.)... 

FIGURE 10 Particle size computation with imaging techniques (a) powder NIR image (particles are in black) (b) statistics. 

Methodology Six samples were analyzed three passed the dissolution test (good samples) and three failed (bad samples). Several ingredients were used as references Avicel (cellulose), the API, magnesium stearate, and poloxamer. Dissolution was tested after NIR imaging measurement to obtain the wet chemical references. 

Method The sample contained starch, API, Avicel, crospovidone, and sodium lauryl sulfate. Sample and references were analyzed in triplicate by NIR imaging (Spectral Dimensions, 20 coadds, spectral range 1100-2450nm). Full image size was 320 x 256 pixels or 4.1 x 3.3 mm. The NIR images were interpreted, and sample raw materials mapped, using PLS classification with five loadings (based on the reference spectra for starch, API, Avicel, crospovidone, and sodium lauryl sulfate). 

Results and Discussion The PLS model identified all five chemical species. PLS multivariate analysis showed (Figure 18) that the core contained Avicel and API and that the periphery contained starch and crospovidone. The solution to the granulation issue was to add a premixing step to avoid agglomeration. NIR imaging proved useful for improving process understanding. 

FIGURE 20 Capsule control by NIR imaging (image size 33 mm x 41mm). Simulation of empty capsule in blister. 

NIR imaging was able to detect empty capsules and monitor fillings, including pellet appearance. 

For implementations that rely upon d.c. signal detection, such as the LCTF NIR imaging system, subtraction of the so-called dark response is critical. There are two components of this response, one that is wavelength independent, the detector response when no photons are impinging on the array, a characteristic of the... 

Taylor, S. K. and McClure, W. F. (1990) NIR imaging spectroscopy measuring the distribution of chemical components. In Near Infrared Spectroscopy (M. Iwamoto and S. Kawano, eds), Korin Publishing Co. Ltd., Japan, pp. 393 104. 

---