Preprocessing Methods in NIR Spectroscopy

Preprocessing has long been a standard practice in NIR spectroscopy, likely because it was a key component to the earliest applications of NIR technology in the food and agricultural industry in the 1960s. As applied NIR technology and enabling technologies have matured over the past several decades, so have the scope and complexity of preprocessing options that are at the method developer’s disposal. Much like a customer shopping for a solution to a specific problem, this expansion is a double-edged sword for the NIR method developer: The presence of more options improves the chances of finding a more effective solution to one’s specific problem, but it also challenges the method developer to better understand and differentiate the attributes of these options. With the above in mind, the objective of this chapter is the following: to allow NIR method developers to better understand, and thus to better assess, the value of the ever-expanding repertoire of preprocessing solutions.