Development of Workflows for Discrete Standard Deposition Using Echo Acoustic Liquid Handlers for qMSI

A thorough understanding of drug pharmacokinetics and target interaction within complex biological environments is critical for successful drug discovery. Quantitative matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI; qMSI) presents a promising avenue for such investigations. While initial qMSI calibration strategies, including tissue mimetics and manual standard applications, have shown limited success, this study introduces an improved protocol leveraging the precision of echo acoustic liquid handling for the accurate deposition of nanoliter drug volumes prior to MALDI-qMSI analysis. This protocol introduces code to facilitate discrete standard deposition of nanoliter compound volumes using ImageJ in tandem with Echo 650/655 acoustic liquid handlers. We further discuss sample preparation guidelines, and best practices for developing calibration curves for subsequent analyses using this approach.