MALDI-MSI: a fast and reliable method for direct melatonin quantification in biological fluids

Abstract

Background: This work reports, for the first time, a validated methodology for qualitative and quantitative melatonin analyses directly from a complex matrix, namely rat milk, using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), in a useful strategy for fast assessment of this molecular species. Methods: This novel approach uses the imaging feature of a MALDI instrument to create bidimensional images of a selected area. Results for sample concentration are expressed as a function of pixel-by-pixel intensity in grayscale, which are quantified according to pixel intensity through ImageJ open source software. For the extent of this work, two conditions were monitored: light-and dark-obtained milk.

Fast Quantification Without Conventional Chromatography, The Growing Power of Mass Spectrometry

“…The use of MALDI-MS as a quantitative tool is usually overlooked, especially for small molecules where the matrix interferes to a large extent in the analysis by forming intense cluster ions in the low m / z range (commonly termed “chemical noise”). However, MALDI-MS has significant advantages as it offers a simplified sample preparation, the formation of predominantly singly charged ions, substantial tolerance for additives and salts, and a much faster speed of analysis (i.e., higher throughput). − In fact, validated quantitative MALDI-MS methods for single analytes exist in the literature. − A targeted MALDI-time-of-flight (ToF) validated method was used to quantify a drug delivery agent within a cell culture . The method was robust, simple and fast and it was superior to the gold standard LC-MS/MS in terms of sensitivity, linear range, solvent consumption and speed of analysis .…”