The purpose of this study is to evaluate the applicability of electrospray laser desorption ionization (ELDI) mass spectrometry imaging (MSI) to interrogate tablet formulations for the spatial distributions of ingredients. ELDI combines laser
ablation via an ultraviolet laser with electrospray ionization to create spatially resolved molecular images. The general ablation setup and process of ELDI-MSI can be seen in Figure 1. Mass spectrometry imaging is a non-targeted technique
allowing the concurrent detection of different classes of small molecules from a solid sample surface. This is ideal for the analysis of pharmaceutical preparations. Five Marian undergraduate students are working on this project.
While we have previously shown that ELDI-MSI on pills is possible (Figure 2) we are currently working to expand the capabilities of the method to further explore agglomeration of the active ingredient, and the form by which the active ingredient
exists in the pill with high accuracy. Here at Marian, we are building our ELDI-MSI setup with a brand new Q-Spark 266 nm nanosecond high-power laser (RPMC Lasers) coupled with our Thermo Scientific LTQ XL linear ion trap mass spectrometer. This
is the same instrument used by many pharmaceutical companies for routine analysis. The ultimate goal of this project is to diagnose agglomeration of the active ingredient in tablets with MSI molecular images and determine the percentage of the
active ingredient existing in the crystalline versus amorphous forms. This project is funded by AbbVie Inc., North Chicago, IL. All samples are provided by AbbVie.
Figure 1. General setup of ELDI-MSI method. The pill sample is mounted on a glass slide which is rastered by a xyz micro-translational stage under a static laser beam.
Figure 2. ELDI-MSI of acetaminophen tablets. A) “Filler” compound at m/z 112.0844. A steady signal across the entire tablet surface was observed for these filler compounds. The MS-images in B, C, D, and E show the spatial
distributions of acetaminophen [M+H]+ at different crystallinity percentages, with the same normalized heat map intensity scale.
Contact Dr. Patrick McVey