Lack of selectivity in sample preparation ‒ An achilles heel of compound-specific isotope analysis for environmental micropollutants

The role of compound-specific isotope analysis (CSIA) in environmental research has been proven over the last few decades. Despite advances in analytical methods and instrumentation, applying CSIA to low-concentration environmental contaminants, especially at the field scale, remains limited. In this perspective paper, we argue that this limitation stems from underdeveloped sample preparation techniques, particularly the lack of required selectivity. Drawing from an extensive review of nearly 600 CSIA studies on contaminants, we (i) analyze methodologies' distribution and dedication to field studies, discussing their connection with the maturity of suitable sample preparation techniques. Additionally, we (ii) examine general trends in sorbent phase technologies, assessing their adequacy to meet CSIA's targeted nature and applicability to micropollutants. In advocating for a paradigm shift, we (iii) emphasize the need to adapt future CSIA development strategies in light of past and current innovations.