Hitting the Jackpot – development of gas chromatography–mass spectrometry (GC–MS) and other rapid screening methods for the analysis of 18 fentanyl‐derived synthetic opioids

Functionalized Gold Nanoparticles and Halogen Bonding Interactions Involving Fentanyl and Fentanyl Derivatives

Fentanyl (FTN) and synthetic analogs of FTN continue to ravage populations across the globe, including in the United States where opioids are increasingly being used and abused and are causing a staggering and growing number of overdose deaths each year. This growing pandemic is worsened by the ease with which FTN can be derivatized into numerous derivatives. Understanding the chemical properties/behaviors of the FTN class of compounds is critical for developing effective chemical detection schemes using nanoparticles (NPs) to optimize important chemical interactions. Halogen bonding (XB) is an intermolecular interaction between a polarized halogen atom on a molecule and e--rich sites on another molecule, the latter of which is present at two or more sites on most fentanyl-type structures. Density functional theory (DFT) is used to identify these XB acceptor sites on different FTN derivatives. The high toxicity of these compounds necessitated a "fragmentation" strategy where smaller, non-toxic molecules resembling parts of the opioids acted as mimics of XB acceptor sites present on intact FTN and its derivatives. DFT of the fragments' interactions informed solution measurements of XB using 19F NMR titrations as well as electrochemical measurements of XB at self-assembled monolayer (SAM)-modified electrodes featuring XB donor ligands. Gold NPs, known as monolayer-protected clusters (MPCs), were also functionalized with strong XB donor ligands and assembled into films, and their interactions with FTN "fragments" were studied using voltammetry. Ultimately, spectroscopy and TEM analysis were combined to study whole-molecule FTN interactions with the functionalized MPCs in solution. The results suggested that the strongest XB interaction site on FTN, while common to most of the drug's derivatives, is not strong enough to induce NP-aggregation detection but may be better exploited in sensing schemes involving films.

Improved separation of fentanyl isomers using metal cation adducts and high-resolution ion mobility-mass spectrometry

Fentanyl is a potent synthetic opioid that has attracted significant attention due to its illegal production and distribution, resulting in misuse, overdose, and fatalities. Because numerous fentanyl analogs, including structural isomers, with different potency have been discovered in the field, there is a critical need to continue developing analytical methodologies capable of accurate identification in forensic and clinical laboratories. This study aimed to develop a rapid method for detecting and separating fentanyl isomers based on ion mobility-mass spectrometry (IM-MS), where IM separates gas-phase ions based on differences in their size, shape, and charge. Several strategies for improved differentiation were implemented, including using unconventional cation adducts (e.g., alkali and transition metals) and data post-processing by high-resolution demultiplexing. A collection of collision cross section (CCS) values for the various metal ion adducts was gathered, which can be used to improve confidence of identification in future samples. Notable examples, such as [M + Cu]+ and [M + Ag]+ adducts, contributed to significant improvement of resolution between isomers. Furthermore, the addition of high-resolution post-processing provided resolving power of >150, which constitutes a significant increase in comparison with the normal 50-60 obtained with low-resolution drift tube instruments. Collectively, these improved separation strategies allowed for confident detection and subsequent quantitative analysis. The optimized IM-MS method resulted in quantification of fentanyl in human urine with limits of detection and quantification of 13 pg/mL and 40 pg/mL, respectively.

Detection of contraband drugs in forensic-correctional mental health services using TeknoScan-a gas chromatography tool

Substance misuse is a major problem among individuals involved in forensic-correctional mental health services. Urine drug screening detects substance use and deters the entry of contraband into forensic-correctional units, albeit with limitations. For example, a point-of-care urine sample may not be possible and patients can alter or substitute samples to avoid detection, highlighting the role of ancillary tools to detect contraband substances. This study describes the pattern and types of substances detected from environmental samples using a gas chromatographic analyzer (TeknoScan TSI3000) in forensic-correctional populations to model the benefits of similar tools in similar settings. Samples collected over 18 months (January 2020 to June 2021) by trained staff members using the machine were reviewed. During this period, 217 environmental samples were recorded, and 66 (30%) samples were positive for contraband substances, including tetrahydrocannabinol (25%), methamphetamines (19%), and cocaine (16%). Other substances detected include methylene-dioxymethamphetamine, heroin, morphine, lysergic acid diethylamide, tramadol, and methyl-benzoate. Fewer positive samples were detected, especially during the time corresponding with the COVID-19 restriction on the forensic units. TeknoScan was beneficial as an ancillary tool to detect and deter contraband substances. It also provided evidence for risk management. Adequate training is needed for the successful implementation of the tool.

Rapid SERS assay for determination of the opioid fentanyl using silver-coated sharply branched gold nanostars

A high-throughput surface-enhanced Raman scattering (SERS)-sensing platform is presented for FNT detection in human urine without any sample preparation. The sensing platform is based on plasmonics-active silver-coated sharply branched gold nanostars (SGNS). The effect of silver thickness was investigated experimentally and theoretically, and the results indicated that SERS enhancement was maximum at an optimum silver thickness of 45 nm on the sharply spiked SGNS. The proposed high-throughput SERS platform exhibited ultrahigh sensitivity and excellent enhancement uniformity for a model analyte, i.e., crystal violet. Moreover, the SERS-sensing platform demonstrated good sensitivity of FNT spiked in human urine samples with two differential linear response ranges of 2 to 0.2 µg/mL and 0.1 µg/mL to 100 pg/mL, respectively,  with a detection limit as low as 10.02 pg/mL. The spiked human urine samples show satisfactory recovery values from 92.5 to 102% with relative standard deviations (RSD) of less than 10%. In summary, the high-throughput performance of the proposed microplate-based SERS platform demonstrated great potential for rapid low-cost SERS-based sensing applications.

Evaluation of portable gas chromatography-mass spectrometry (GC-MS) for the analysis of fentanyl, fentanyl analogs, and other synthetic opioids

Potent synthetic opioids including fentanyl and its analogs are frequently encountered in the field and require detection and identification by first responders to maintain the safety of drug abusers, first responders, health-care providers, and the public at large. Due to the low concentration at which these substances may be encountered and the complicating matrices within which they may be dispersed, the use of portable gas chromatography-mass spectrometry (GC-MS) for their identification in the field offers great potential value. This research established that portable GC-MS is a useful method for the detection and identification of a large number of synthetic opioids, especially fentanyl and its analogs. In this study, 250 synthetic opioids and related substances including 210 fentanyl analogs were analyzed using portable GC-MS. It was concluded that 225 of the 250 (90.0%) opioids analyzed were successfully detected onboard at the time of analysis and identified as either the substance (55.2%) or an analog (34.8%). These outcomes have equivalent benefit for the field analysis of illicit drugs due to both initiating the same subsequent actions by first responders.

Evaluation of fentanyl immunoassay test strips for rapid in-situ detection of fentanyl and fentanyl analogs in seized samples and alternative matrices

BACKGROUND

Ion mobility spectrometry is used for the rapid detection of drugs at points of security but are unable to differentiate some drugs leading to the instrument alarming for a drug not present in the sample. This can be particularly problematic for samples that alarm for fentanyl. In this study, fentanyl immunoassay strips were evaluated for use as a secondary test for fentanyl, including for the testing of alternative matrices, such as powders, e-liquids, and infused papers and textiles.

METHODS

The limit of detection of fentanyl immunoassay strips was examined along with their selectivity to 18 fentanyl analogsand 72 other drugs and cutting agents. The effectiveness of the test strips at the detection of fentanyl in the presence of other drugs was examined by testing a series of concentrations of fentanyl in solution in combination with other drugs. The testing of alternative matrices was explored with laboratory prepared samples through sampling with cotton buds and extraction in water.

RESULTS

The fentanyl immunoassay strips detected fentanyl at concentrations of 45 ng/mL and reacted with 16 of 18 tested fentanyl analogs with carfentanil and norfentanyl being the only analogs to not react. There was no reactivity with other drugs or cutting agents. The effectiveness of the fentanyl test strips was not reduced when fentanyl was mixed with other drugs. Fentanyl was successfully detected with high sensitivity in all alternative matrices.

CONCLUSION

The fentanyl immunoassay strips were found to be an effective secondary test for fentanyl and at least 16 fentanyl analogs in seized drug samples, including when mixed with other drugs. The effectiveness of the sampling methods for alternative matrices should be further evaluated using fentanyl and fentanyl analog casework samples. The use of this method by law enforcement and other agencies should be examined to assess its effectiveness and ease of use in operational settings.

Ultra-trace SERS detection of cocaine and heroin using bimetallic gold-silver nanostars (BGNS-Ag)

A rapid, in-field, and reliable method for the detection of illegal drugs of abuse in biological fluids without any sample pretreatment would potentially be helpful for law enforcement, drug control officials, and public healthcare. In this study, we presented a cost-effective and highly reproducible solution-based surface-enhanced Raman scattering (SERS) platform utilizing a portable Raman instrument for fast sensitive SERS detection of illegal drugs, such as cocaine, and heroin in human urine without any sample preprocessing. The SERS platform was constructed for the first time by combining the superior SERS enhancement properties of bimetallic silver-coated gold nanostars (BGNS-Ag) and the advantages of suitable alkaline metal salts such as NaI for SERS signal amplification. The effects of the silver thickness of BGNS-Ag and alkaline salts on the SERS performance were investigated in detail; we observed that the maximum SERS enhancement was obtained for BGNS-Ag with the maximum silver thickness (54 ± 5 nm) in presence of NaI salt. Our SERS platform shows ultra-high sensitivity of cocaine and heroin with a limit of detection (LOD) as low as 10 pg/mL for cocaine and 100 pg/mL for heroin, which was 100 times lower than that of the traditional silver nanoparticle-based illegal drug detection. As a demonstration, the platform was further applied to detect cocaine and heroin spiked in human urine without any sample preprocessing achieving a LOD of 100 pg/mL for cocaine and 1 ng/mL for heroin. Overall, our SERS detection platform shows potential for rapid, onsite, ultra-low-cost portable applications for trace detection of illegal drugs and biomarkers.

Molecular Insights and Clinical Outcomes of Drugs of Abuse Adulteration: New Trends and New Psychoactive Substances

Adulteration is a well-known practice of drug manufacturers at different stages of drug production. The intentional addition of active ingredients to adulterate the primary drug may enhance or mask pharmacological effects or may produce more potent drugs to increase the number of available doses and the dealer's profit. Adulterants found in different drugs change over time in response to different factors. A systematic literature search in PubMed and Scopus databases and official international organizations' websites according to PRISMA guidelines was performed. A total of 724 studies were initially screened, with 145 articles from PubMed and 462 from Scopus excluded according to the criteria described in the Method Section. The remaining 117 records were further assessed for eligibility to exclude articles without sufficient data. Finally, 79 studies were classified as "non-biological" (n = 35) or "biological" (n = 35 case reports; n = 9 case series) according to the samples investigated. Although the seized samples analyses revealed the presence of well-established adulterants such as levamisole for cocaine or paracetamol/acetaminophen for heroin, the reported data disclosed new adulteration practices, such as the use of NPS as cutting agents for classic drugs of abuse and other NPS. For example, heroin adulterated with synthetic cannabinoids or cocaine adulterated with fentanyl/fentalogues raised particular concern. Notably, adulterants play a role in some adverse effects commonly associated with the primary drug, such as levamisole-adulterated cocaine that may induce vasculitis via an autoimmune process. It is essential to constantly monitor adulterants due to their changing availability that may threaten drug consumers' health.

Augmentation of MS/MS Libraries with Spectral Interpolation for Improved Identification

Tandem mass spectrometry (MS/MS) is a primary tool for the identification of small molecules and metabolites where resultant spectra are most commonly identified by matching them with spectra in MS/MS reference libraries. The high degree of variability in MS/MS spectrum acquisition techniques and parameters creates a significant challenge for building standardized reference libraries. Here we present a method to improve the usefulness of existing MS/MS libraries by augmenting available experimental spectra data sets with statistically interpolated spectra at unreported collision energies. We find that highly accurate spectral approximations can be interpolated from as few as three experimental spectra and that the interpolated spectra will be consistent with true spectra gathered from the same instrument as the experimental spectra. Supplementing existing spectral databases with interpolated spectra yields consistent improvements to identification accuracy on a range of instruments and precursor types. Applying this method yields significant improvements (∼10% more spectra correctly identified) on large data sets (2000–10 000 spectra), indicating this is a quick yet adept tool for improving spectral matching in situations where available reference libraries are not yet sufficient. We also find improvements of matching spectra across instrument types (between an Agilent Q-TOF and an Orbitrap Elite), at high collision energies (50–90 eV), and with smaller data sets available through MassBank.

Fentanyl analog trends in Washington D.C. observed in needle-exchange syringes

Fentanyl has played a significant role in the opioid crisis, proving to be a persistent problem due to its analgesic effects and addictive nature. Consequently, fentanyl analogs have been identified as a rising threat in the illicit drug market, contributing to thousands of both fatal and nonfatal overdoses in the United States. A profile of the fentanyl and fentanyl analogs present in Washington D.C. was developed by analyzing syringe extracts obtained from needle-exchange programs in the city. Gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) acquisition provided a targeted analysis scheme to detect trace amounts of nine compounds: acetyl fentanyl, para-fluorofentanyl, fentanyl, methoxyacetyl fentanyl, meta-chlorofentanyl, carfentanil, valeryl fentanyl, beta-hydroxythiofentanyl, and furanyl fentanyl. In total, 332 syringe extracts were analyzed. The detected analytes and their percent prevalences were fentanyl (72.29 %), acetyl fentanyl (11.44 %), para-fluorofentanyl (6.63 %), and furanyl fentanyl (3.61 %). Tandem use was detected with combinations of fentanyl with acetyl fentanyl (12.08 %), fentanyl with para-fluorofentanyl (7.08 %), fentanyl with furanyl fentanyl (4.58 %), and fentanyl with acetyl fentanyl and para-fluorofentanyl (2.08 %). The identities of the analogs present, their relative potencies, and tandem use trends provides valuable information, especially for medical personnel who respond to opioid-related overdoses and deaths. Based on the fentanyl analog trends and tandem use of these compounds revealed in this study, it is recommended that Congress passes the permanent classification of fentanyl analogs as Schedule I drugs.

Gold-Trisoctahedra-Coated Capillary-Based SERS Platform for Microsampling and Sensitive Detection of Trace Fentanyl

A cost-effective and highly reproducible capillary-based surface-enhanced Raman scattering (SERS) platform for sensitive, portable detection and identification of fentanyl is presented. Through encapsulating gold trisoctahedra (Au TOH) in the capillary tube for the first time, the SERS platform was constructed by combining the superior SERS properties of Au TOH and the advantages of capillaries in SERS signal amplification, facile sample extraction, and portable trace analysis. The effects of the size and density of Au TOH on the SERS performance were investigated by experiments and simulations, which showed that the maximum SERS enhancement was obtained for Au TOH with the size of 75 nm when particle density reached 74.54 counts/μm². The proposed SERS platform possesses good reproducibility with a relative standard deviation (RSD) of less than 5%. As a demonstration, the platform was applied to detect fentanyl spiked in aqueous solution and serum samples with a limit of detection (LOD) as low as 1.86 and 40.63 ng/mL, respectively. We also validated the feasibility of the designed platform for accurate identification of trace fentanyl adulterated in heroin at mass concentration down to 0.1% (10 ng in 10 μg total). Overall, this work advances more explorations on capillary-based SERS platform to benefit portable trace analysis.

Determination of synthetic opioids in oral fluid samples using fabric phase sorptive extraction and gas chromatography-mass spectrometry

New psychoactive substances (NPS) continue to emerge in the drug market every year, becoming a global threat to public health and safety. These compounds are mostly synthetic cannabinoids and designer cathinones. However, synthetic opioids have appeared on the recreational drug markets in recent years, particularly fentanyl and its derivatives ("fentanyls"). Fentanyl and its analogs are related to harmful intoxications and an increase in opioid-related mortality in many countries, such as in the United States and Europe in the last years. Taking the drug related global crisis into consideration, this work developed and validated an effective and sensitive method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of 11 fentanyl analogs in oral fluid samples. The extraction was carried out using a sol-gel Carbowax 20 M sorbent immobilized on 100% cellulose fabric substrate and using ethyl acetate as the desorption solvent. The limits of detection (LODs) and quantification (LOQs) ranged from 1 to 15 ng mL^-1 and 5 to 50 ng mL^-1, respectively. Intra-day and inter-day precision were found within 8.2% and 8.6%, respectively, while accuracy ranged from -5.5 to 9.1%, in accordance with the established criteria. The absolute recovery values were in the range of 94.5%-109.1%. The validated method demonstrated its great potential to detect and quantify fentanyl analogs in possible forensic work and off-site analysis in road traffic cases.

Synthetic opioids: a review and clinical update

The term 'opioids' refers to both the natural compounds ('opiates') which are extracted from the opium poppy plant (Papaver somniferum) and their semi-synthetic and synthetic derivatives. They all possess relatively similar biochemical profiles and interact with the opioid receptors within the human body to produce a wide range of physiological effects. They have historically been used for medicinal purposes, their analgesic and sedative effects, and in the management of chronic and severe pain. They have also been used for non-medicinal and recreational purposes to produce feelings of relaxation, euphoria and well-being. Over the last decade, the emergence of an illegal market in new synthetic opioids has become a major global public health issue, associated with a substantial increase in unintentional overdoses and drug-related deaths. Synthetic opioids include fentanyl, its analogues and emerging non-fentanyl opioids. Their popularity relates to changes in criminal markets, pricing, potency, availability compared to classic opioids, ease of transport and use, rapid effect and lack of detection by conventional testing technologies. This article expands on our previous review on new psychoactive substances. We now provide a more in-depth review on synthetic opioids and explore the current challenges faced by people who use drugs, healthcare professionals, and global public health systems.

Development and evaluation of a synthetic opioid targeted gas chromatography mass spectrometry (GC-MS) method

As seized drug casework becomes increasingly complex due to the continued prevalence of emerging drugs, laboratories are often looking for new analytical approaches including developing methods for the analysis of specific compounds classes. Recent efforts have focused on the development of targeted gas chromatography mass spectrometry (GC-MS) confirmation methods to compliment the information-rich screening results produced by techniques like direct analysis in real time mass spectrometry (DART-MS). In this work, a method for the confirmation of synthetic opioids and related compounds was developed and evaluated. An 11-component test solution was used to develop a method that focused on minimizing overlapping retention time acceptance windows and understanding the influence of instrument parameters on reproducibility and sensitivity. Investigated settings included column type, flow rate, temperature program, inlet temperature, source temperature, and tune type. Using a DB-200 column, a 35-min temperature ramped method was created. It was evaluated against a suite of 222 synthetic opioids and related compounds, and successfully differentiated all but four compound pairs based on nonoverlapping retention time acceptance windows or objectively different mass spectra. Compared to a general confirmatory method used in casework, the targeted method was up to 25 times more sensitive and provided at least a two-fold increase in retention time differences. Analysis of extracts from actual case samples successfully demonstrated utility of the method and showed no instance of carryover, although the high polarity column required wider retention time windows than other columns.

Suspect Screening of Fentanyl Analogs Using Matrix-Assisted Ionization and a Miniature Mass Spectrometer with a Custom Expandable Mass Spectral Library

The reliable identification of fentanyl and its analogs is of great significance for public security. However, with the growing prevalence of fentanyl compounds, current analytical strategies cannot fully meet the need for fast and high-throughput detection. In this study, a simple, rapid, and on-site analytical protocol was developed based on a miniature mass spectrometer. A dramatically simplified workflow was implemented using matrix-assisted ionization, bypassing complex sample pretreatment and chromatographic separation. The tandem mass spectrometry (MS/MS) capability afforded by the miniature ion trap mass spectrometer facilitated the investigation of fragmentation patterns for 49 fentanyl analogs during collision-induced dissociation, revealing valuable information on marker fragment ions and characteristic neutral loss. Calculations on Laplacian bond order values further verified the mass spectrometric behavior. A computation-assisted expandable mass spectral library was constructed in-house for fentanyl compounds. Smart suspect screening was carried out based on the full-scan MS and MS/MS data. The present study demonstrates an appealing potential for forensic applications, enabling streamlined screening for the presence of illicit fentanyl compounds at the point of seizures of suspect samples.

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.