Porous framework materials as advanced adsorbents in needle trap devices (NTDs): A critical review

Sample preparation is a critical step in analytical chemistry, particularly for the accurate analysis of organic pollutants in complex matrices including biological and environmental samples. Recent advancements in microextraction techniques, such as needle-trap devices (NTDs), have shown promise in enhancing analyte extraction efficiency, selectivity, and stability. In the NTD technique, sampling is performed by extracting samples from the air, the headspace of solutions, and soil using an adsorbent contained inside the needle. The type of employed adsorbent is one of the most key factors influencing the selectivity and efficiency of NTDs. Recently, porous materials such as Metal-Organic Frameworks (MOFs) and Porous Organic Frameworks (POFs) have garnered significant attention for their potential to enhance NTD performance. This review provides a comprehensive and critical overview of the NTD technique, with a specific focus on the role of MOF- and POF-based adsorbents, including covalent organic frameworks (COFs) and porous aromatic frameworks (PAFs). The fundamental principles of NTD operation, along with the structural characteristics, extraction performance, and application scope of these porous adsorbents in different matrices, are systematically discussed. In addition, the current status of greenness assessment of NTD-based methodologies is reviewed, with emphasis on studies employing analytical green metrics such as AGREE and AGREEprep. The limitations of existing evaluations and the lack of comprehensive, standardized greenness assessments are highlighted. Finally, the key challenges, research gaps, and future perspectives for the development and application of MOF- and POF-based adsorbents in NTDs are outlined, providing guidance for advancing both analytical performance and sustainability in sample preparation.