(Un)targeted Scanning of Locks of Hair for Drugs of Abuse by Direct Analysis in Real Time-High-Resolution Mass Spectrometry

Ambient Ionization Mass Spectrometry: Application and Prospective

Mass spectrometry (MS) is a formidable analytical tool for the analysis of non-polar to polar compounds individually and/or from mixtures, providing information on the molecular weights and chemical structures of the analytes. During the last more than one-decade, ambient ionization mass spectrometry (AIMS) has developed quickly, producing a wide range of platforms and proving scientific improvements in a variety of domains, from biological imaging to quick quality control. These methods have made it possible to detect target analytes in real time without sample preparation in an open environment, and they can be connected to any MS system with an atmospheric pressure interface. They also have the ability to analyze explosives, illicit drugs, disease diagnostics, drugs in biological samples, adulterants in food and agricultural products, reaction progress, and environmental monitoring. The development of novel ambient ionization techniques, such as probe electrospray ionization, paper spray ionization, and fiber spray ionization, employed even at picolitre to femtolitre solution levels to provide femtogram to attogram levels of the target analytes. The special characteristic of this ambient ion source, which has been extensively used, is the noninvasive property of PESI of examination of biological real samples. The results in the current review supports the idea that AIMS has emerged as a pioneer in MS-based approaches and that methods will continue to be developed along with improvements to existing ones in the near future.

Application of direct analysis in real-time mass spectrometry (DART-MS) in forensic science: a comprehensive review

Background

As the rate of crime is constantly increasing, the workload on the forensic analyst also piles up. The availability of a limited number of seized samples makes it crucial to directly analyze the sample, thereby preventing wastage in the prior steps of sample preparation. Due to such needs, the forensic community is consistently working on broadening the usage of direct analysis in real-time mass spectrometry (DART-MS). DART-MS is a relatively new technique for rapid mass spectral analysis. Its use for chemical analysis credits its ability to analyze the sample at atmospheric pressure.

Main body

This article gives insight into the ionization mechanisms, data analysis tools, and the use of hyphenated techniques like thermal-desorption-DART-MS, infrared-thermal-desorption-DART-MS, Joule-heating thermal-desorption-DART-MS, etc. This review summarizes the applications of DART-MS in the field of Forensic Science reported from 2005 to 2021. The applications include analysis of drugs, warfare agents, gun-shot residues, ink differentiation, and other forensically relevant samples. The paper also presents the relation between the type of DART-MS technique and the ionization mode used for a particular class of compounds.

Conclusion

The review follows that the high-resolution mass-spectrometers or low-resolution mass-spectrometers systems in the positive or negative mode were highly dependent on the type of analyte under investigation. Drugs, inks, dyes, and paints were mainly analyzed using the positive ionization mode in the HRMS technique. The examinations of fire accelerants predominantly used the positive ionization mode in the LRMS technique. Moreover, the limit of detection values obtained from the qualitative screening of street drugs were of ppb level, indicating high sensitivity of DART-MS. Considering the work done in the past years, there are potential future research needs of this technology, especially in forensic science.

Graphical Abstract

Rapid characterization of drugs in a single hair using thermal desorption ionization mass spectrometry

Hair remains the most common type of physical evidence found in most crime scenes. However, the amount of hair found at a crime scene is limited and analysis of drugs in hair by gas chromatography mass spectrometry (GC-MS) or liquid chromatography tandem mass spectrometry (LC-MS/MS) is laborious and time-consuming. In this study, a rapid and simple method is developed using thermal desorption ionization mass spectrometry (TDI-MS) to analyze drugs directly in a single hair. A single hair is put onto a heated metal ceramic heater (MCH) and then a high voltage direct current and solvent are applied to the single hair. The drugs in the hair are thermally desorbed and ionized, and subsequently transferred to the MS inlet and detected. A typical hair analysis can be completed in a few minutes. This novel technique provides a new orientation for forensic scientists to study drugs in a single hair that is found at a crime scene, on a suspect, or on a victim.

Ocfentanil testing in hair from a fatality case: Comparative analysis of a lock of hair versus a single hair fiber

In clinical and forensic toxicology, hair analysis offers a larger window for detecting drug exposure than blood or urine. Drug measurements are generally carried out using a segmented lock of hair, but few articles report the use of a single hair to document drug exposure. Nevertheless, single hair analysis can be very useful, particularly if only small amounts of biological matrices are available. More data on analyzing new synthetic opioids (NSOs) in hair are needed to help interpretation in future cases. In this study, segmental single hair analysis is compared with segmental hair lock analysis to document an ocfentanil-related death. The hair lock and single hair analyses were performed using the LC-MS/MS method after decontamination and incubation. Ocfentanil (OcF) concentrations ranged from 42 to 150 pg/mg in the segmented hair lock, depending on the segments. The hair lock and single hair analyses showed similar results: the highest concentrations were measured in the first two centimeters and decreased from root to tip. The similar profiles obtained from both the lock of hair and the single hair demonstrate the relevance of single hair analysis in cases where very few data are available. This article describes OcF concentrations in an authentic hair sample after a documented intake of this molecule in a fatality.

Rapid Distinction and Semiquantitative Analysis of THC and CBD by Silver-Impregnated Paper Spray Mass Spectrometry

The control over the amount of psychoactive THC (Δ-9-tetrahydrocannabinol) in commercial cannabidiol (CBD) products has to be strict. A fast and simple semiquantitative Ag(I)-impregnated paper spray mass spectrometric method for differentiating between THC and CBD, which show no difference in standard single-stage or tandem MS, was established. Because of a different binding affinity to Ag(I) ions, quasi-molecular Ag(I) adducts [THC + Ag]+ and [CBD + Ag]+ at m/z 421 and 423 give different fragmentation patterns. The product ions at m/z 313 for THC and m/z 353 and 355 for CBD can be used to distinguish THC and CBD and to determine their ratio. Quantification of THC/CBD ratios in commercial CBD oils was accomplished with a low matrix effect (-2.2 ± 0.4% for THC and -2.0 ± 0.3% for CBD). After simple methanol extraction (recovery of 87.3 ± 1.2% for THC and 92.3 ± 1.4% for CBD), Ag(I)-impregnated paper spray analysis was employed to determine this ratio. A single run can be completed in a few minutes. This method was benchmarked against the UHPLC-UV method. Ag(I)-impregnated paper spray MS had the same working range (THC/CBD = 0.001-1) as UHPLC-UV analysis (R2 = 0.9896 and R2 = 0.9998, respectively), as well as comparable accuracy (-2.7 to 14%) and precision (RSD 1.7-11%). The method was further validated by the analysis of 10 commercial oils by Ag(I)-impregnated paper spray MS and UHPLC-UV analysis. Based on the determined relative concentration ratios of THC/CBD and the declared CBD concentration, 6 out of 10 CBD oils appear to contain more THC than the Dutch legal limit of 0.05%.

Advances in drugs of abuse testing

Drugs of abuse testing is widely used clinically and forensically. Urine is the preferred type of specimen for drugs of abuse screening, but saliva, sweat, hair, and meconium are emerging types of specimens. GC-MS has been used as a gold standard for confirmatory drug testing, but LC-tandem-MS can analyze more diverse types of analytes than GC-MS. Thus, LC-tandem-MS becomes a new gold standard for confirmatory drug testing. Unlike GC-MS, LC-tandem-MS is not suited for non-targeted comprehensive drug screening. But with the advent of high-resolution-MS such as Tof-MS, which can discriminate the compounds of similar molecular masses but with different formulas, LC-hybrid-Tof-MS is usable for non-targeted comprehensive drug screening. Another technical advancement is the advent of miniature ambient ionization MS, which can analyze biological specimens including urine within one minute. Thus these mass spectrometers are promising for rapid drugs of abuse testing in a POC setting.

Hyphenated high-resolution mass spectrometry-the "all-in-one" device in analytical toxicology?

This trend article reviews papers with hyphenated high-resolution mass spectrometry (HRMS) approaches applied in analytical toxicology, particularly in clinical and forensic toxicology published since 2016 and referenced in PubMed. The article focuses on the question of whether HRMS has or will become the all-in-one device in these fields as supposed by the increasing number of HRMS presentations at scientific meetings, corresponding original papers, and review articles. Typical examples for the different application fields are discussed such as targeted or untargeted drug screening, quantification, drug metabolism studies, and metabolomics approaches. Considering the reviewed papers, HRMS is currently the only technique that fulfills the criteria of an all-in-one device for the various applications needed in analytical toxicology.

Graphical abstract

MASS SPECTROMETRY ANALYSIS OF DRUGS OF ABUSE: CHALLENGES AND EMERGING STRATEGIES

Mass spectrometry has been the "gold standard" for drugs of abuse (DoA) analysis for many decades because of the selectivity and sensitivity it affords. Recent progress in all aspects of mass spectrometry has seen significant developments in the field of DoA analysis. Mass spectrometry is particularly well suited to address the rapidly proliferating number of very high potency, novel psychoactive substances that are causing an alarming number of fatalities worldwide. This review surveys advancements in the areas of sample preparation, gas and liquid chromatography-mass spectrometry, as well as the rapidly emerging field of ambient ionization mass spectrometry. We have predominantly targeted literature progress over the past ten years and present our outlook for the future. © 2020 Periodicals, Inc. Mass Spec Rev.

Rapid determination of chemical composition in the particulate matter of cigarette mainstream smoke

Particulate matter from mainstream smoke (MSS) is significantly hazardous when inhaled into the human body. An ambient ionization mass spectrometric method, direct analysis in real time mass spectrometry (DART-MS), was applied to rapidly and simultaneously measure multiple particulate components in MSS. A variety of compounds were obtained in seconds, where different types of cigarettes and different solvent extracts generated distinct chemical constituents as validated by principle component analysis. Chemical formula assignment and compound identification were based on accurate m/z values with mass errors <10 ppm. Quantitation of nicotine was achieved using an isotope internal standard with DART-MS. Method validation with chromatographic-MS analysis further proved the advantages of DART-MS with respect to analysis speed and operational simplicity for the direct evaluation of complex samples. DART-MS is feasible for the rapid acquisition of cigarette fingerprints for quality control as well as for quantitative assessment of carcinogens for harm reduction.

Nitrogen direct analysis in real time time-of-flight mass spectrometry (N2 DART-TOFMS) for rapid screening of forensic drugs

RATIONALE

Over the last ten years, helium direct analysis in real time time-of-flight mass spectrometry (He DART-TOFMS) has become an established technique in rapid screening of forensic drugs to decrease the time necessary to triage forensic drug cases, therefore contributing to backlog reduction and more timely criminal prosecution. Recently, we demonstrated that N₂ DART was able to efficiently ionize all polar compounds except for a few extremely small ones such as methanol and acetonitrile. Therefore, N₂ DART-TOFMS should be a suitable technique for rapid screening of forensic drugs.

METHODS

Nitrogen direct analysis in real time time-of-flight mass spectrometry (N₂ DART-TOFMS) was performed using a JEOL AccuTOF mass spectrometer with an IonSense DART-100 ion source. A 3-min analytical protocol was used for the analysis of each sample. Sample introduction was accomplished by moving the closed end of a melting point capillary where approximately 1 μL sample solution was deposited or the exposed inside of a freshly cut tablet across the N₂ gas stream between the DART-100 ion source and orifice 1 of the AccuTOF.

RESULTS

Ten commonly abused drugs, eight synthetic cannabinoids and four controlled prescription drugs (CPDs) were analyzed. The limit of detection (LOD) was determined to be approximately 10 μg/mL or 10 pg in quantities. All drugs at the LOD level were positively identified using their [M + H]⁺ ions with mass errors less than 5 mDa. The identification were further supported by in-source fragment ions and characteristic N₂ DART ions that are not commonly generated by He DART, e.g. [M + H + O]⁺ and [M + H + 2O]⁺ ions.

CONCLUSIONS

It was concluded that the 3-min analytical protocol could be utilized in the analysis of seized drugs in the form of tablets and powders or prepared in solution. In consideration that N₂ is readily available in the air and He is a non-renewable resource, N₂ DART-TOFMS is a greener, cheaper and more convenient alternative to He DART-TOFMS in rapid screening of forensic drugs.

Natural Product Discovery by Direct Analysis in Real Time Mass Spectrometry

Direct analysis in real time mass spectrometry (DART MS) is one of the first ambient ionization methods to be introduced and commercialized. Analysis by DART MS requires minimal sample preparation, produces nearly instantaneous results, and provides detection over a broad range of compounds. These advantageous features are particularly well-suited for the inherent complexity of natural product analysis. This review highlights recent applications of DART MS for species identification by chemotaxonomy, chemical profiling, genetic screening, and chemical spatial analysis from plants, insects, microbes, and metabolites from living systems.

Chemical Markers for Short- and Long-Term Areca Nut Exposure

Background: Areca nut (AN) chewing causes oral cancer. AN cessation programs are the most effective approach to reduce AN chewing induced cancers but require biomarkers to determine program compliance and success. Objectives: To explore chemical markers for short- and long-term AN exposure using non-invasively collected saliva, buccal cells (BCs), and scalp hair of chewers. Methods: Saliva was collected from a male chewer before and up to 2 days after AN chewing. Saliva was separated into supernatant and pellet (BCs) then analyzed by spectrophotometry and liquid chromatography (LC) with UV/VIS detection. Scalp hair was collected from four chewers and analyzed for areca alkaloids using direct analysis in real time-tandem mass spectrometry (DART-MSMS). Results: The red pigmented saliva after chewing showed no valuable signals when either the saliva supernatant or pellet (BCs) were analyzed by spectrophotometry. Saliva analysis by LC-UV/VIS showed diagnostically valuable signals at 488 nm up to 5 and 24 h post chewing in the supernatant and pellet, respectively. DART-MSMS analysis detected two of the four AN specific alkaloids (arecoline and arecaidine) in male but none in female hair. Conclusions/Importance: LC-UV/VIS analysis of the red pigments extracted from saliva and BCs after AN chewing showed distinct signals up to 24 h post chewing while DART-MSMS analysis in BCs and scalp hair showed selective signals of AN alkaloids for several weeks or months after AN exposure. Chemical hair treatment might prevent detection of areca alkaloids in hair. AN cessation trials and other programs now have essential tools for bioverification.

Rapid Analysis of Illegal Cationic Dyes in Foods and Surface Waters Using High Temperature Direct Analysis in Real Time High-Resolution Mass Spectrometry

A high temperature desorption (HTD) direct analysis in real time-high-resolution mass spectrometric (DART-HRMS) method was developed for the rapid analysis of four banned cationic dyes. Rhodamine B is used to dye foods, while malachite green, crystal violet, and methylene blue are added to fishponds as antimicrobials. A simple induced phase separation extraction was used to pretreat samples. The DART-HRMS method employed two temperature steps, i.e., 200 °C for drying, purification, and enrichment of sample solution and 500 °C for thermal desorption and ionization of analytes. The calibration curves of dyes in the range of 50-2000 ng/mL were linear using deuterated malachite green as an internal standard. The LODs vary for all analytes between 0.1 and 30 ppb depending on the matrix and experimental conditions. Through analyses of real samples, two chili powders and one chili oil were found to be contaminated by rhodamine B. The concentrations were comparable with those found by an HPLC-MS/MS method.

Ambient Ionization and Miniature Mass Spectrometry Systems for Disease Diagnosis and Therapeutic Monitoring

Mass spectrometry has become a powerful tool in the field of biomedicine. The combination of ambient ionization and miniature mass spectrometry systems could most likely fulfill a significant need in medical diagnostics, providing highly specific molecular information in real time for clinical and even point-of-care analysis. In this review, we discuss the recent development of ambient ionization and miniature mass spectrometers as well as their potential in disease diagnosis and therapeutic monitoring, with an emphasis on their capability in analysis of biofluids and tissues. We also speculate the future development of the integrated, miniature MS systems and provide our perspectives on the challenges in technical development as well as possible solutions for path forward.

Sodiation-based in-source collision for profiling of pyranocoumarins in Radix Peucedani (Qianhu): utility of sodium adducts' stability with in-source collision

Full scan mode of liquid chromatography-mass spectrometry equipped with an electrospray ionization source offers a chance on global detection of complicated components; however, the scan mode carries significant challenges in rapidly capturing information of analysts. Sodiation-based in-source collision was proposed here, as a technique for rapid detecting untargeted analytes in full scan analysis, which was based on the stability of sodium adducts and the nonselectivity of in-source collision. Then the technique was applied to profile of angular-type pyranocoumarins (APs) in Radix Peucedani, with full scan analysis performed at two specific in-source collision energy: a high energy 50 V that is tolerated by the sodium adducts of APs, and a low energy 10 V, at which abundant adducts were offered. The spectra list of two average mass spectra was exported, and stable ions were selected based on the intensity ratio of standards at the two collision energy. Then 27 plausible [M + Na]⁺ m/z values of APs were acquired after filtering the fragment ion and isotope ions and validating with [M + NH₄ ]⁺ . Eighty-two APs finally were tentatively identified based on their accurate spectral data of MSⁿ , fragmentation rules, and elution order regardless of their absolute configuration, which included 25 reported APs from Peucedanum praeruptorum Dunn. The technique provided a novel application of sodium adduct in qualitative analysis. And it was valuable for rapidly capturing information of analytes in full scan analysis, not only for APs but also for other compounds that could form sodium adducts. Copyright © 2017 John Wiley & Sons, Ltd.

Critical comparison of mass analyzers for forensic hair analysis by ambient ionization mass spectrometry

RATIONALE

Recently, several direct and/or ambient mass spectrometry (MS) approaches have been suggested for drugs of abuse imaging in hair. The use of mass spectrometers with insufficient selectivity could result in false-positive measurements due to isobaric interferences. Different mass analyzers have been evaluated regarding their selectivity and sensitivity for the detection of Δ9-tetrahydrocannabinol (THC) from intact hair samples using direct analysis in real time (DART) ionization.

METHODS

Four different mass analyzers, namely (1) an orbitrap, (2) a quadrupole orbitrap, (3) a triple quadrupole, and (4) a quadrupole time-of-flight (QTOF), were evaluated. Selectivity and sensitivity were assessed by analyzing secondary THC standard dilutions on stainless steel mesh screens and blank hair samples, and by the analysis of authentic cannabis user hair samples. Additionally, separation of isobaric ions by use of travelling wave ion mobility (TWIM) was investigated.

RESULTS

The use of a triple quadrupole instrument resulted in the highest sensitivity; however, transitions used for multiple reaction monitoring were only found to be specific when using high mass resolution product ion measurements. A mass resolution of at least 30,000 FWHM at m/z 315 was necessary to avoid overlap of THC with isobaric ions originating from the hair matrix. Even though selectivity was enhanced by use of TWIM, the QTOF instrument in resolution mode could not indisputably differentiate THC from endogenous isobaric ions in drug user hair samples.

CONCLUSIONS

Only the high resolution of the (quadrupole) orbitrap instruments and the QTOF instrument in high-resolution mode distinguished THC in hair samples from endogenous isobaric interferences. As expected, enhanced selectivity compromises sensitivity and THC was only detectable in hair from heavy users. Copyright © 2016 John Wiley & Sons, Ltd.