Addressing the challenges in forensic drug chemistry II

These times continue to be thought-provoking and exciting for stakeholders involved in all aspects of forensic drug chemistry. Challenges can be tremendous, for example, when having to face large numbers of sample turnover in a short amount of time or when having to deal with submissions that go beyond the identification of “typical” or well-established controlled substances. New drugs continuously appear on the market, and standard reference material may not always be immediately available. Exciting opportunities also arise from the plethora of activities and sample types one might receive for analysis or organic synthesis. The present collection of articles provides stimulating examples that involve various aspects of drug chemistry. The value and development of drug profiling programs over the years cannot be underestimated, and it is gratifying to see how the field has adapted to face the challenges as they have arisen throughout the years. Adapting existing methods of sample preparation and analysis—including the exploration of chemometrics and employment of stable ratio analysis—offer tremendous opportunities. On the other hand, the authors and topics featured in this collection of articles remind the reader of the complex interplay between products containing controlled substances, new psychoactive substances, dietary supplements, and/or falsified/counterfeit medicines. The presence of pharmaceuticals in products offered for open sale on the Internet and the challenges that might be encountered when working on the differentiation between isomers keep the forensic drug chemist vigilant and busy. This special issue can be considered a follow-up of one published in Volume 9, Issue 3, in March 2017,1 and it is hoped that the present collection of exciting articles will give readers across the disciplines valuable insights into the fascinating opportunities associated with drug-related work. Establishing a fully dedicated drug profiling program requires concerted efforts and significant investments in facilities and people. The chemical profiling of controlled substances has always been an important cornerstone of forensic work, and one emphasis has specifically been placed on the analysis of heroin, cocaine, and amphetamine-type substances. It is therefore appropriate to kick-start this special issue with a contribution by Michael Collins from the National Measurement Institute (NMI) in New South Wales (Australia) who provides a historical perspective on the principles, development, challenges and limitations of chemical profiling. It sets the stage for this important type of work and highlights how a close collaboration between forensic chemists and law enforcement investigators is needed to serve the various stakeholders involved in the overlapping areas of science, law, and public health.2 The benefits and challenges that can arise from a close collaboration between law enforcement agencies and forensic laboratories have been echoed by Meola and Esseiva who offer a Swiss perspective. There are opportunities to minimize potential loss of valuable intelligence, and further work currently underway will evaluate how illicit drug profiling results are used and how they might be used to increase value.3 According to the United Nations Office on Drugs and Crime, the methamphetamine market continuously increased globally in recent years, which is also reflected by increased purity and seizure numbers.4 In addition, the costs of dismantling and cleaning up synthetic drug production laboratories (not to mention the impact on the environment) are high.5 Toske and McKibben from the Special Testing and Research Laboratory of the US Drug Enforcement Administration (DEA) have contributed an illuminating two-decade review of the DEA's methamphetamine profiling program that was initiated in 1997. Since inception, the collected US data suggest that there was a gradual shift from using a pseudoephedrine or ephedrine precursor to a range of 1-phenylpropan-2-one (P2P)-based methods, which involved a number of different methods and pre-precursors. The presented work also illustrates the importance of preparedness and readiness when it comes to monitoring developing trends in illicit drug manufacturing.6 An Australian overview is presented by Helen Salouros from the Australian NMI in New South Wales that covers the period between 2011 and 2020. Similar to observations made in the United States, many changes in the chemical profile of methamphetamine have been observed, which also extended to exploring more analytical methodologies, such as stable isotope ratio analysis.7 One of several precursors to P2P is α-phenylacetoacetonitrile (APAAN, 3-oxo-2-phenylbutanenitrile), which can be subjected to hydrolysis under acidic conditions. For this reason, it serves as a pre-precursor (“designer” precursor) to (meth)amphetamine. Another P2P precursor is methyl α-phenylacetoacetate (MAPA) that has recently been added to Table 1 of the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, 1988.8 However, this means that novel and non-controlled alternatives are becoming of interest to drug manufacturers in an attempt to maintain access to the preparation of P2P. Three potential alternatives have been investigated by Tsujikawa et al who explored their conversion to P2P under acidic conditions. Ethyl 3-oxo-2-phenylbutyrate (EAPA), methyl 3-oxo-4-phenylbutyrate (MGPA), and ethyl 3-oxo-4-phenylbutyrate (EGPA) were converted to P2P though EAPA conversion was reported to be somewhat more sluggish. Under basic conditions, MGPA and EGPA were converted to P2P, and EAPA was mainly converted to phenylacetic acid. In addition, the authors observed GC-induced degradation of these pre-precursors.9 Typically, a key analytical method in drug profiling work involves the use of gas chromatography–mass spectrometry (GC-MS), and therefore, it can be considered a consistent part in the drug chemist's toolbox. As shown by Greif and colleagues, the use of liquid chromatography–high-resolution mass spectrometry (LC-HRMS) delivers important contributions to the field, which also means that approaches involving LC-MS are becoming increasingly accepted in the field. The authors investigated wastewater samples that originated from controlled amphetamine synthesis (Leuckart route). One of the advantages included the detection of nonvolatile and also thermolabile compounds in aqueous synthesis waste samples, and the authors also reported the tentative identification of seven potential synthesis markers.10 Another nontargeted LC-HRMS methodology was implemented by Carby-Robinson et al who developed a profiling model using cocaine samples. The authors selected 12 marker compounds and employed combinations of pretreatment and distance measures. This retrospective approach—when treated with chemometric tools—aided in the development of a comparative profiling model without prior knowledge of links between samples or prior knowledge of the target markers.11 One of the questions associated with clandestine drug production in houses relates to their fate and/or their degradation following their deposition on surfaces inside dwellings. Mayer et al presented a proof-of-concept study that investigated the interaction of methamphetamine with the common gaseous indoor oxidant nitrous acid and found that the detection of the suspected carcinogenic and mutagenic N-nitrosomethamphetamine could potentially present a risk to public health in properties contaminated with methamphetamine.12 A retrospective study involving the analysis of methamphetamine profiles obtained from the Australian Federal Police was carried out by Popovic and colleagues who explored the feasibility of using drug profiles for the understanding of drug markets at a strategic and operational level. Relational, temporal, spatial, and quantitative analyses were applied to specimen linkages. Intelligence produced at various levels could also allow for relevant law enforcement agencies to take necessary measures in disrupting markets.13 Analysis of drugs by stable isotope ratio mass spectrometry (IRMS) has become increasingly frequent. As shown by Lansdown and colleagues, the combination of IRMS and organic impurity profiling allowed for the correct assignment of methamphetamine samples synthesized from different pre-precursors and reductive amination.14 In another contribution from the DEA's Special Testing and Research Laboratory, Thompson and coworkers performed IRMS analyses on preparative HPLC collected morphine from opium and on heroin samples after hydrolysis to morphine, which allowed the investigators to corroborate regional differences for deacetylated heroin's carbon and nitrogen data with the data of morphine samples isolated from authentic opium collected from those growing regions.15 In the world of doping control analysis, the misuse of testosterone and boldenone preparations and how they can be differentiated from steroids produced in vivo is of significant concern to scientists working in the field of sports drug testing. Piper and Thevis analyzed seized samples of testosterone and boldenone products using carbon isotope ratios (CIR). The authors suggested that pharmaceutical preparations usually show more depleted 13C values compared with endogenous steroids though some exceptions were also identified.16 Jones et al from the DEA's Special Testing and Research Laboratory provided a valuable contribution that details advances in their cocaine signature program in relation to alkaloid and isotope profiles. Stable isotope ratio analyses of cocaine extracted from plant material collected in Peru are presented to assist in future geo-sourcing activities.17 The analysis of seized material for the presence of controlled substances is one of the bread and butter activities in a forensic laboratory. Submissions of falsified and counterfeit medicines can be part of that job. Blakey et al report the results from the analysis of 46 tablets from 20 seizures passed on as various benzodiazepine-containing specimen. Their survey included the assessment of dosage levels of four benzodiazepines across five different types of tablets and involved the detections of other non-declared benzodiazepines including those considered new psychoactive substances or “designer” benzodiazepines.18 Although these results were reported from Queensland (Australia), the work on the analysis of seized benzodiazepine tablets presented by Downey et al from Ireland also gives fascinating insights into the types of tablets that might be encountered during seizures. Three types of tablets sold illicitly as diazepam specimen were found to contain 2-methylamino-5-chlorobenzophenone, 2-amino-3-(2-chlorobenzoyl)-5-ethylthiophene, and/or etizolam in various combinations. The detection of the benzophenone and thiophene intermediates (used for the manufacturing of diazepam and etizolam)—especially in the absence of diazepam—was particularly surprising.19 Another very interesting case was reported by Rosenberger and coworkers who analyzed a collection of three fizzy drink samples obtained from suppliers operating on the Internet. These so-called “dirty sprite” drinks are offered for sale and labeled to contain pharmaceutical substances promethazine and codeine. Interestingly, the authors report detections of cocaine, codeine promethazine, and dihydrocodeine.20 Depending on the analytical conditions involved in the identification process, the differentiation between isomers can have important consequences in cases where some are controlled and others are not. An example was reported by Brandt and colleagues who explored a variety of methods to differentiate between the three isomeric lysergamides LSD, MIPLA, and LAMPA. This question arose during the analysis of blotters expected to contain the N-methyl-N-isopropyl isomer of LSD (MIPLA).21 Increasing interest has emerged when it comes to the differentiation between enantiomeric substances, and this challenges was taken on by Losacker et al who report on the analysis of amphetamine (n = 143), 3,4-methylendioxy-N-methamphetamine (MDMA) (n = 94), and methamphetamine (n = 528) samples seized in southern Germany in 2019 and 2020. A chiral LC-MS/MS method was employed and confirmed that amphetamine and MDMA samples consisted of racemic mixtures, whereas the majority of methamphetamine samples consisted of (S)-methamphetamine and some samples also revealed the presence of the (R)-enantiomer.22 This special issue concludes with the analysis of products sold as dietary supplements that are also familiar to drug chemists working in a forensic environment. Costa and colleagues present the analysis of samples advertised as caffeine-containing pre-workout supplements marketed in Brazil and reported that the information on the product label was by no means always accurate, which included the detection of caffeine not being listed on the label at all and some that exceeded recommended daily intake doses.23 Finally, the contribution from Pawar et al from the US Food and Drug Administration presents the quantitative analysis of 58 collected products associated with thyroid management (via Internet between 2017 and 2018) using five hormones as reference material. Both glandular and nonglandular products were collected and surveyed for their hormone content.24 The guest editors would like to express their gratitude to all authors and reviewers for their contributions to this special issue. The support received from Prof. Mario Thevis, and Paul Trevorrow is also thankfully appreciated. The guest editors would also like to thank Dr. Adam Cawley for instigating the communication between the two. Data sharing not applicable to this article as no datasets were generated or analysed during the current study