Boehringer Ingelheim: Implementation of Variable Pathlength Technology at Boehringer-Ingelheim Fremont

Absorption spectroscopy is used to quantify biomolecules using Beer’s Law: Absorbance (A) = Molar Absorptivity (ε) * Pathlength (L) * Concentration (c). A = ε L c

At high concentrations, samples must be diluted due to limitations of traditional spectroscopy instrumentation utilizing a fixed pathlength of 1 cm. A gravimetric correction is applied to ensure accuracy of dilution. The process of diluting, applying the gravimetric correction and washing the cuvette is time consuming and can take several hours in a controlled setting such as Quality Control (QC) or Manufacturing. The use of Variable Pathlength Extension eliminates the need to dilute samples by taking absorbance measurements at multiple pathlengths using a disposable optical fibrette and sample vessel. The software plots absorbance vs. pathlength. Using Linear regression, the software calculates a slope for the points and determines the concentration by rearranging Beer’s Law to: A/L = slope = ε c. Use of Variable Pathlength for concentration measurements results in time savings of greater than 80%.