E.L. Holthoff, M.E. Farrell, L.S. Marcus, P.M. Pellegrino
US Army Research Laboratory, United States
pp. 392 - 395
Keywords: inkjet printer, droplet calibration, droplet optimization, hazard detection
Hazard detection systems must be evaluated with appropriate test material concentrations under controlled conditions in order to accurately identify and quantify unknown residues commonly utilized in theater. The existing assortment of hazard reference sample preparation methods/techniques presents a range of variability and reproducibility concerns, making it increasingly difficult to accurately assess optically based detection technologies. To overcome these challenges, we are examining the optimization, characterization, and calibration of microdroplets from an inkjet printer that has a proven capability for the preparation of energetic reference materials. Research presented herein focuses on the development of a simplistic printer calibration technique and sample preparation protocol for explosive materials testing based on drop-on-demand technology. Droplet mass and reproducibility were measured using ultraviolet-visible (UV-Vis) absorption spectroscopy. The results presented here demonstrate the operational factors that influence droplet dispensing for specific materials (e.g., energetic and interferents). Understanding these parameters permits the determination of droplet and sample uniformity and reproducibility (typical R2 values of 0.991, relative standard deviation or RSD ≤ 5%), and thus the demonstrated maturation of a successful and robust methodology for energetic sample preparation.