Carbon and hydrogen isotope analysis of triacetone triperoxide using solid-phase microextraction coupled to GC-IRMS

The source inference of triacetone triperoxide (TATP) is of great significance in the fight against crime. Isotope ratio mass spectrometry (IRMS) is a reliable method for accurately measuring the isotope ratio, and it has been successfully used to differentiate and trace various explosives, including TATP. However, the current studies are not suitable for analyzing trace amounts of TATP in complex matrices. The matrix at the explosion site is complex, with severe interference and low levels of explosive residues, which makes it difficult to extract the explosive residues. Therefore, an effective method for extracting and enriching TATP is necessary before conducting IRMS analysis. Solid-phase microextraction (SPME) is an efficient extraction technology that combines extraction, concentration and sample injection. In this study, SPME-gas chromatography-isotope ratio mass spectrometry (GC-IRMS) method based on isoreticular metal-organic framework-8 (IRMOF-8) coated fiber was established for the first time for the analysis of δ¹³C and δ²H signatures of TATP. The limits of detection of δ¹³C and δ²H signatures of TATP were 100 ng and 9 µg, respectively, with measurement errors of 0.36 ‰ and -3.75 ‰. The IRMOF-8-coated fiber exhibited better mechanical stability and a lower limit of detection compared to the commercial polydimethylsiloxane (PDMS) fiber. Using the established method, six TATP samples from different sources were distinguished accurately. The impact of matrix (soil and tap water) on δ¹³C and δ²H signatures of TATP was also investigated. The established method demonstrated high sensitivity and precision, making it suitable for in-situ extraction and source of trace explosive residues in explosion cases.