Comparison of Activation Techniques for the Identification of Nitazene Analogs Using the NIST/NIJ Data Interpretation...

Direct analysis in real time (DART) and electrospray ionization (ESI) are commonly used in forensic science and are combined with different activation techniques, which impact the degree and type of fragmentation. Therefore, this study compares collision-induced dissociation (CID), in-source CID (IS-CID), and all ions fragmentation (AIF) activation for nitazene analog identification using the NIST/NIJ Data Interpretation Tool (DIT).

DART and ESI were used to analyze 18 nitazene analogs on a quadrupole time-of-flight (Q-TOF) mass spectrometer. CID, IS-CID, and AIF were explored with DART, and CID was used for ESI analysis. All activation techniques included the use of low, medium, and high activation energies. The resulting data were compared with the NIST DART-MS Forensics Database using the NIST/NIJ DIT.

The CID spectra were generally less noisy and had fewer ions than the IS-CID or the AIF spectra. The IS-CID spectra generated higher mass-to-charge (m/z) product ions and had fewer characteristic product ions than either CID or AIF. The NIST/NIJ DIT correctly identified 14/18 nitazene analogs when using AIF compared with 13/18 correct identifications using both CID and IS-CID. The ESI-CID data produced 12/18 correctly identified samples.

All three activation techniques performed similarly, based on the NIST/NIJ DIT results. However, IS-CID produced significantly less fragmentation than CID or AIF, indicating that AIF is a suitable screening technique for this instrumental setup. The NIST/NIJ DIT can also be utilized for ESI-CID spectra, although slightly fewer nitazene analogs were correctly identified with ESI-CID than with DART-CID.