Nova abordagem para a análise direta de matrizes em estado nativo por espectrometria de massas ambiente

Abstract

Chemical analyses using mass spectrometry have traditionally relied on sample preparation steps that consume time and resources. Extraction protocols, particularly for complex and diverse matrices, rarely recover all compounds of interest with equal efficiency. Direct Analysis in Real Time Mass Spectrometry (DART-MS) is an ambient ionization technique that has gained relevance across different fields of knowledge, but its potential for the direct analysis of raw samples (i.e., matrices in their native state, without extraction) remains limited by significant challenges, such as poor standardization and difficulties in sample handling/positioning, instrumental contamination, carryover, and thermal damage to the matrices. Thus, although DART-MS has gained considerable attention for its potential to enable analyses without sample preparation, most of its applications still involve extraction and processing protocols. The objective of this thesis was to develop a new analytical approach to overcome these challenges and, consequently, enable the direct analysis of raw matrices by DART-MS. The proposed strategy — named PERM (Permeably Enclosed Raw Matrices) — is based on confining the sample within a semipermeable enclosure coupled to a 3D-printed positioning device. The implementation of this new approach eliminated instrumental contamination, protected the samples from thermal damage, standardized the analytical process, and preserved the acquisition of informative chemical profiles without extraction, solubilization, or any other type of sample preparation. In addition, dedicated software was developed to address the specific demands that emerged from the newly introduced analytical system. The complete approach (concept, physical device, and software) was applied to and evaluated across a broad set of forensic, toxicological, and food-related matrices, with particular emphasis on its application to the chemical profiling of seized drugs, where it enabled the detection of high-value substances — e.g., synthetic-route markers, adulterants, and contaminants — that were not detected in the corresponding extracts analyzed by the extraction- based approach used by forensic authorities. A comprehensive methodological study demonstrated that simple parameters, such as temperature, analysis time, and positioning, can modulate the analytical response by orders of magnitude, enabling the selective enrichment of analytes without targeted extraction. Guidelines were proposed for establishing validation protocols for the direct analysis of raw matrices. Finally, the approach was further improved (PERM 2.0) to integrate automated sequential analyses in scanning mode (i.e., no longer in static mode), which increased sensitivity and markedly reduced the overall variability of the obtained signal. Altogether, PERM emerges as an innovative, low-cost approach that enables direct, rapid, and reliable qualitative analyses by DART-HRMS.