Spectroscopic Techniques Raman, Infrared, and Laser-Induced Breakdown Spectroscopy Identification of Particles in Raw Materials Kathryn Lee, Markus Lankers, and Oliver Valet Abstract Raw materials need to be of a certain quality with respect to physical and chemical composition. They also need to have no contaminants, including particles, because these could indicate raw material impurities or contaminate the product. Particle identification allows determination of process conditions that caused them and whether the quality of the final product is acceptable. Particles may appear to the eye to be very different things than they actually are. They may be coated with the raw material and may consist of several components; therefore, chemical and elemental analyses are required for accuracy in proper identification and definitive information about their source. Thus, microscope versions of Raman spectroscopy, laser-induced breakdown spectroscopy (LIBS), and infrared (IR) spectroscopy are excellent tools for identifying particles in materials. Those tools are fast and accurate, and can provide chemical and elemental composition as well as images that can aid identification. The micro-analysis capabilities allow for easy analysis of different portions of samples so that multiple components can be identified and sample preparation can be reduced or eliminated. The differ- ences in sensitivities of Raman and IR spectroscopies to different functional groups as well as the elemental analysis provided by LIBS and the image analysis provided by the microscopy makes these complementary techniques and provides the advantage of identifying various chemical components. Proper spectral searching techniques and interpretation of the results are important for interpretation and identification of trace contaminants. Keywords Raman, infrared, IR, laser-induced breakdown spectroscopy, LIBS, identification, particles, raw materials Date received: 8 June 2017; accepted: 19 October 2017 Introduction The main objective and significance of this study was to develop and implement methods to efficiently and correctly identify particles in raw materials so that the sources of particles could be determined. The control and elimination of particle sources are important to product quality. Visibly different particles in excipients are of great importance to the pharmaceutical industry. The concern over particle presence has escalated due to United States Food and Drug Administration (FDA) adverse findings for the insuf- ficiency of the investigation process of unusual, visible par- ticles. 1,2 Identification 3 allows evaluation of the severity of the contamination regarding the quality and safety of the product, and source determination and possible elimin- ation. There are often regulations regarding particles. There are equipment cleaning requirements for processing machinery, 4 injectable drugs must be visually inspected to be essentially particle free 5 , and containers must be visually examined for contamination. 6 Raw materials are to be sampled and tested for the absence of contamination to prevent adulteration of finished products. 7 When particles are seen in raw materials, it is important to know what they are and how they got there so that the quality of products will be acceptable. The identification of those particles needs to be fast and accurate. Knowing what the particles are will give important information about the quality of the material, and if they are indeed unwanted material, then finding the source quickly to pre- vent future particles is important. Historically, microscopy was used to identify particles by determining their micro rap.ID Inc., Monmouth Junction, NJ, USA Corresponding author: Kathryn Lee, Lab Head, rap.ID Inc, 11 Deer Park Drive, Suite 201, Monmouth Junction, NJ 08852, USA. Email: kathrynalee@hotmail.com Applied Spectroscopy 0(0) 1–11 ! The Author(s) 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0003702817742791 journals.sagepub.com/home/asp