Qualitative identification of fentanyl and other synthetic opioids using ambient ionization high resolution time-of-flight mass spectrometry
Moore, Amanda Marie
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The Centers for Disease Control and Prevention deemed the increase in overdose fatalities, due to the use of opioids, an “opioid epidemic” in the United States. Heroin, fentanyl, and other synthetic opioids are commonly abused and are contributing to the opioid epidemic. In 2016, the Drug Enforcement Administration temporarily placed three fentanyl analogs (beta-hydroxythiofentanyl, butyryl fentanyl, and furanyl fentanyl) under Schedule I due to their imminent threat to public health. These drugs elicit analgesic effects similar to heroin making them desirable drugs to abuse. Novel fentanyl analogs and designer opioids are expected to become more prominent in forensic casework in the near future as the opioid epidemic continues. These drugs can be seen in forensic seized drug and urine casework samples either alone or mixed with other drugs of abuse. It is therefore necessary to have an efficient methodology to identify these new compounds. Currently, gas chromatography-mass spectrometry (GC/MS) is used to identify drugs of abuse and is considered the “gold standard” in forensic casework. However, analysis times can often range from 15 to 60 minutes in length. Another drawback is the need for spectral library matching, which requires analytical reference materials for identification. Therefore, the identification of novel fentanyl analogs and designer drugs is limited until a reference material becomes available. In this study, direct sample analysis time-of-flight mass spectrometry (DSA-TOFMS) was evaluated to provide rapid identification of fentanyl and other synthetic opioids in seized drug and urine casework samples. DSA is a direct ambient ionization source, which requires no chromatography and minimal sample preparation. TOFMS is a high resolution mass spectrometer that uses collision-induced dissociation (CID) to produce precursor ion and characteristic fragmentation ions, which provide additional structural and molecular formula information, allowing for the identification of compounds without a reference material. The analytes explored in this study include: heroin, 6-monoacetylmorphine (6-MAM), morphine, fentanyl, norfentanyl, 4-anilino-N-phenethylpiperidine (4-ANPP), acetyl fentanyl, beta-hydroxythiofentanyl, butyryl fentanyl, furanyl fentanyl, valeryl fentanyl, AH-7921, U-47700, buprenorphine, norbuprenorphine, desomorphine, MT-45, W-15, and W-18. Direct sample analysis time-of flight mass spectrometry (DSA-TOFMS) is a novel instrumentation that could be utilized in the forensic sciences field to qualitatively identify illicit substances in casework samples. In this study, 19 compounds of interest containing heroin, fentanyl, fentanyl analogs, and other synthetic opioids were evaluated using DSA-TOFMS. DSA-TOFMS abbreviated the workload of the analysis and was utilized to provide precursor ion and characteristic fragmentation ions within an analysis time of 20 seconds. Certified reference standards were used to optimize instrumentation settings, to determine precursor ions and characteristic fragmentation ions, and to determine the limit of detection of the instrument. A carryover study determined there were no persisting ions present when entering the capillary inlet between runs. A repeatability study revealed the DSA-TOFMS repeated results within the acceptable criteria range of above 500 counts and within 10ppm error 93% (10ppm) and 83% (1ppm). Forensic seized drug casework samples were evaluated with DSA-TOFMS and qualitatively identified. Out of the 64 samples, 89% were qualitatively identified as heroin, 4% were qualitatively identified as fentanyl, 1% was qualitatively identified as heroin and fentanyl, 3% were qualitatively identified as acetyl fentanyl, and 3% were qualitatively identified as furanyl fentanyl. The casework samples containing furanyl fentanyl were considered “true unknown unknown samples,” as the Maine Health and Environmental Testing Laboratory gas chromatography-mass spectrometry library did not have a spectrum to use for the identification of these samples. Forensic urine casework samples were evaluated with DSA-TOFMS. Samples previously confirmed to contain compounds of interest were prepared using minimal sample preparation technique (filtered using 0.45 microns syringe filters and diluted (1:10) with LC/MS grade water). Analysis displayed the limitations of DSA-TOFMS as only twelve of the forty compounds of interest were present and only three of the twelve were within the acceptable criteria range. DSA-TOFMS is a fast and reliable technique with minimal sample preparation for forensic seized drug samples. However, the concentration in complex matrixes, such as urine and blood, were unable to be qualitatively identified using this sample preparation method by DSA-TOFMS.