Investigating a Drop-on-Demand Microdispenser for Standardized Sample Preparation

Report No. ARL-TR-5726
Authors: Ellen L. Holthoff, Mikella E. Hankus, Keeley Q. Tober, and Paul M. Pellegrino
Date/Pages: September 2011; 26 pages
Abstract: The existing collection of reference sample preparation methods presents a range of variability and reproducibility concerns, making it increasingly difficult to assess chemical detection technologies, especially in regard to techniques that are spatially dependent. To overcome these challenges, we are examining the optimization, characterization, and calibration of microdroplets from a drop-on-demand (DOD) microdispenser that is ideal for the preparation of energetic reference materials. Current research focuses on the development of a sample preparation protocol for explosive materials testing based on DOD technology. The results presented here demonstrate the operational factors that influence droplet dispensing of specific materials (e.g., energetic and interferent). Ultraviolet-visible (UV-Vis) absorption spectroscopy and Raman spectroscopy are used to investigate droplet and sample uniformity and reproducibility (typical calibration goodness of fit R2 values of 0.991, relative standard deviation or RSD ≤5%). DOD results are compared to samples prepared using a drop-and-dry method.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2011