Hyperpolarisation of Mirfentanil by SABRE in the Presence of Heroin

Mirfentanil, a fentanyl derivative that is a μ‐opioid partial agonist, is hyperpolarised via Signal Amplification By Reversible Exchange (SABRE), a para‐hydrogen‐based technique. [Ir(IMes)(COD)Cl] (IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazole‐2‐ylidene, COD=cyclooctadiene) was employed as the polarisation transfer catalyst. Following polarisation transfer at 6.5 mT, the pyrazine‐protons were enhanced by 78‐fold (polarisation, P=0.04 %). The complex [Ir(IMes)(H)2(mirfentanil)2(MeOH)]+ is proposed to form based on the observation of two hydrides at δ −22.9 (trans to mirfentanil) and −24.7 (trans to methanol). In a mixture of mirfentanil and heroin, the former could be detected using SABRE at concentrations less than 1 % w/w. At the lowest concentration analyzed, the amount of mirfentanil present was 0.18 mg (812 μM) and produced a signal enhancement of −867‐fold (P=0.42 %). following polarisation transfer at 6.5 mT. Mirfentanil detection: Mirfentanil, a fentanyl derivative and μ‐opioid partial agonist, is hyperpolarised via the hyperpolarisation technique Signal Amplification By Reversible Exchange (SABRE). In a series of simulated samples consisting of mirfentanil and heroin, the amount of mirfentanil was varied from 0.63 % w/w–3.80 % w/w. Mirfentanil was readily detected in the 1H NMR spectrum (single transient) at all the concentrations studied when SABRE was employed.