Method validation parameters for drugs and explosives in ambient pressure ion mobility spectrometry

An approach using method validation (MV) parameters, otherwise known as analytical figures of merit was combined with electrospray ionization high performance ion mobility spectrometry (ESI-HPIMS) to describe an approach for evaluating drugs and explosives analysis in the field. MV parameters such as reduced mobility (K _o ), conditional reduced mobility (K _c ), resolving power (R _p ), theoretical plates (N), linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), repeatability, range, and reporting limit were investigated and developed for eleven drugs and six explosives. Our investigation estimated resolving power at 66 ± 0.64 for the ESI-HPIMS used. The LOD’s calculated ranged from 0.45–2.97 ng of material electrosprayed into the ESI-HPIMS. The LOQ’s calculated falls in the range 4.11–8.63 ng of material electrosprayed into the ESI-HPIMS. The key findings from this investigation were the following: K _c proves to be a measure of the identity of an explosive or drug ion; a parameter that may be applied to help aid IMS devices when detecting drugs and explosives. MV parameters, especially, K _c , introduced in this study is an effective parameter for establishing a unique identity of a drug or explosive. A control chart is an effective way to monitor the performance of an instrument and may be a useful tool for establishing reliability of confirmatory data in forensic investigations. MV parameters may be a reliable, accurate and unique identification marker for target drugs and explosives capable of differentiating these substances from false positive responses.     

Detection of explosives on skin using ambient ionization mass spectrometry

Single nanogram amounts of the explosives TNT, RDX, HMX, PETN and their mixtures were detected and identified in a few seconds on the surface of human skin without any sample preparation by desorption electrospray ionization (DESI) using a spray solution of methanol-water doped with sodium chloride to form the chloride adducts with RDX, HMX, and PETN while TNT was examined as the radical anion and tandem mass spectrometry was used to confirm the identifications.     

Rapid screening of explosives in ambient environment by aerodynamic assisted thermo desorption mass spectrometry

Rapid, direct, and trace detection of explosives in an open environment is of particular need in homeland and/or transportation security. In this work, an aerodynamic assisted thermo desorption mass spectrometry method was developed for the direct quantitative analyses of explosives from a distance. Remote non‐volatile explosive sensing was achieved for 2, 4, 6‐trinitrotoluene, trinitrohexahydro‐1, 3, 5‐triazine, 8701 (main ingredient: RDX 98.5%), and C4 (a type of plastic explosive) with a distance of 0.65 m. Furthermore, a close to 324 cm² effective sampling area could be achieved, and the limits of detection are in the ng range. This device can be deployed in airports and subway stations for high‐throughput and automatic luggage/personnel screening of prohibited articles, such as explosives and illicit drugs. Copyright © 2016 John Wiley & Sons, Ltd.     

基于敞开式直接电离质谱技术的尿液中毒品检测北大核心CSCD

尿液作为一种易于获取的体内毒品检材,在吸毒人员快速筛查中被广泛应用。针对传统快速筛查技术存在假阳性率高、定量能力不足以及实验室质谱技术在快速检测中存在前处理复杂、检测耗时长、使用环境苛刻等问题,该文提出了一种基于敞开式直接电离质谱技术的生物样本快速检测方法。该研究采用探针式电喷雾离子源与便携式质谱仪联用快速检测平台,优化了喷雾电压和质谱入口毛细管温度,开发了高效快速的前处理技术。基于该平台和前处理技术,5种常规毒品(甲基苯丙胺、氯胺酮、可卡因、O^(6)-单乙酰吗啡和3,4-亚甲双氧甲基苯丙胺)的尿液加标溶液的检出限为0.5~30 ng/mL,且其中4种毒品定量检测的线性相关系数大于0.99。除此之外,5种常规毒品在3个不同水平下的加标回收率为56.1%~103.7%,多次检测结果的相对标准偏差为9.0%~27.8%,说明联用检测平台与前处理方法结合可以达到良好的准确度。为了进一步检验该联用仪器的实战能力,测试了某社区戒毒康复中心40份阳性和110份阴性实际尿液样本,总体检测的准确率接近99%,且通过一次进样在20 s内可同时检测多种毒品。该研究成果有利于推动快速检测技术的发展,促进敞开式直接电离质谱仪技术的推广应用,提升一线执法服务水平。     

Direct, trace level detection of explosives on ambient surfaces by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization (DESI) mass spectrometry is used to detect trace amounts of explosives present on a variety of ambient surfaces in 5-second analysis times without any sample preparation.     

Negative chemical ionization mass spectrometry of explosives

The negative chemical ionization mass spectra of nitrobenzene, ethylene glycol dinitrate and nitroglycerine have been obtained using various reagent ions. For nitrobenzene, [OH]^? gives the [M ? H]^?, together with [M]^?˙ ions formed by electron capture, but other reagent ions gave relatively low intensity adduct peaks. Ethylene glycol dinitrate and nitroglycerine gave abundant [M + X]^? ions (X = NO₂, NO₃, Cl, Br, I), together with ions arising from the thermal decomposition of the samples in the heated inlet system. The rate of anion attachment to these compounds is much greater than that to related compounds having only one functional group, and it is suggested that this is due to the participation of the adjacent groups in the bonding between the substrate and anion.     

Direct detection of explosives on solid surfaces by mass spectrometry with an ambient ion source based on dielectric barrier discharge

Trace amounts of explosives on solid surfaces were detected by mass spectrometry at ambient conditions with a new technique termed dielectric barrier discharge ionization (DBDI). By the needle-plate discharge mode, a plasma discharge with energetic electrons was generated, which could launch the desorption and ionization of the explosives from solid surfaces. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), and pentaerythritol tetranitrate (PETN) were desorbed directly from the explosives-contaminated surface by DBDI, forming the typical anions of [TNT](-), [TNT - H](-), [RDX + NO(2)](-), [PETN + ONO(2)](-), and [RDX + ONO(2)](-). The ions were transferred into the MS instrument for analysis in the negative ion mode. The detection limit of present method was 10 pg for TNT (m/z 197, S/N 8 : 1), 0.1 ng for RDX (m/z 284, S/N 10 : 1), and 1 ng for PETN (m/z 260, S/N 12 : 1). The present method allowed the detection of trace explosives on various matrices, including paper, cloth, chemical fiber, glass, paints, and soil. A relative standard deviation of 5.57% was achieved by depositing 100 pg of TNT on these matrices. The analysis of A-5, a mixture of RDX and additives, has been carried out and the results were consistent with the reference values. The DBDI-MS method represents a simple and rapid way for the detection of explosives with high sensitivity and specificity, which is especially useful when they are present in trace amounts on ordinary environmental surfaces.     

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

The ultrafast laser-induced photoionization and photodissociation processes of the nitroaromatic containing explosive and explosive related compounds (ERCs) nitrobenzene (NB), 1,3-dinitrobenzene (DNB), m-nitrotoluene (MNT), 2,4-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) have been investigated at three laser wavelengths and power densities using a time-of-flight mass spectrometer. Examination of the mass spectra of these compounds reveals the enhanced formation of the molecular ion [M⁺] when ultraviolet (332 nm) and visible (495 nm) light is used relative to infrared (795 nm) radiation. In addition, at 795 nm and a power density of 3. 5 × 10¹⁴ W/cm², the presence of a competition between multiphoton ionization (MPI) and Coulomb explosion (CE) channels is revealed by peak shape analysis, and is thought to be operative under these conditions for all of the molecules investigated.     

Electrospray ionization with ambient pressure ion mobility separation and mass analysis by orthogonal time-of-flight mass spectrometry.

Rapid screening and identification of drug and other mixtures are possible using a novel ambient pressure high-resolution ion mobility (APIMS) orthogonal reflector time-of-flight mass spectrometer (TOFMS). Departing ions from the APIMS drift tube traversed a pressure interface between the APIMS and TOFMS where they were subjected to numerous gas collisions that could produce selective fragmentation. By increasing the accelerating field in the pressure interface region, the ions generated using water-cooled electrospray ionization (ESI) underwent collision-induced dissociation (CID). Mixtures of ESI ions were separated by APIMS based on their respective size-to-charge (s/z) ratios while CID and analysis of mass-to-charge (m/z) ratios occurred in the pressure interface and TOFMS. Product ions that were formed in this pressure interface region could be readily assigned to precursor ions by matching the mobility drift times. This process was demonstrated by the examination of a mixture of amphetamines and the resulting fragmentation patterns of the mobility-separated precursor ion species [M + H](+).     

Direct analysis of drugs by continuous-flow fast-atom bombardment and tandem mass spectrometry

The techniques of continuous-flow fast-atom bombardment (CF-FAB) and tandem mass spectrometry (MS/MS) are combined and applied to the analysis of small molecular mass drugs (mol.wt less than 500 Da). The approach involves the interfacing of a CF-FAB inlet with a triple-stage quadrupole mass spectrometer, enabling the acquisition of collision-activated decomposition mass spectra of the drugs after FAB ionization. The relationship between a stable sample surface on the CF-FAB probe tip and the quality of the mass spectrum is discussed, as are practical methods for obtaining and maintaining surface stability. CF-FAB MS/MS spectra for several drugs are presented, including penicillin G, phentolamine, cocaine and benzoylecgonine. Minimum detection limits range from 50-500 pg injected, depending on the compound. The reproducibility of the integrated areas of peaks from repetitive injections is approximately five per cent. Data are also presented for the direct CF-FAB MS/MS analysis of cocaine and benzoylecgonine in spiked urine samples.     

介质阻挡放电离子源质谱分析

敞开式离子化质谱可对表面样品进行直接快速分析而受到关注,成为质谱分析的热点研究方向.介质阻挡放电离子源是一种基于等离子体放电机理的敞开式离子源,近年来得到了较快的发展.本文着重介绍该离子源的基本原理、性能特征以及应用进展,并对其发展趋势进行了展望.     

Desorption ionization by charge exchange (DICE) for sample analysis under ambient conditions by mass spectrometry

An ambient pressure ionization technique for mass spectrometric analysis of substances present on solid surfaces was developed. A nebulized spray containing molecular ions of a solvent such as toluene can be generated by passing the solvent through a stainless steel capillary held at a high voltage. When the stream of charged droplets produced in this way is directed onto a solid surface, the analytes present on the surface are desorbed and ionized by a charge exchange process. This technique was shown to desorb and generate positively charged molecular ions from compounds that are not readily ionized by some other ambient methods, under positive-ion generation mode. For example, intense signals representing radical cations of 1,4-hydroquinone, limonene, thymol, and several other compounds were observed when the analytes were deposited on a metal surface and exposed to a toluene spray nebulized from the metal capillary maintained at a potential of about +5 kV. In contrast, when the same samples were exposed to a spray of water/methanol/formic acid under customary DESI-like (positive-ion mode) conditions, no peaks representing the analytes were observed.     

Comparative study on ambient ionization methods for direct analysis of navel orange tissues by mass spectrometry

It is of sustainable interest to improve the sensitivity and selectivity of the ionization process, especially for direct analysis of complex samples without matrix separation. Herein, four ambient ionization methods including desorption atmospheric pressure chemical ionization (DAPCI), heat‐assisted desorption atmospheric pressure chemical ionization (heat‐assisted DAPCI), microwave plasma torch (MPT) and internal extractive electrospray ionization (iEESI) were employed for comparative analysis of the navel orange tissue samples by mass spectrometry. The volatile organic compounds (e.g. ethanol, vanillin, leaf alcohol and jasmine lactone) were successfully detected by non‐heat‐assisted DAPCI‐MS, while semi‐volatile organic compounds (e.g. 1‐nonanol and ethyl nonanoate) together with low abundance of non‐volatile organic compounds (e.g. sinensetin and nobiletin) were obtained by heat‐assisted DAPCI‐MS. Typical nonvolatile organic compounds [e.g. 5‐(hydroxymethyl)furfural and glucosan] were sensitively detected with MPT‐MS. Compounds of high polarity (e.g. amino acids, alkaloids and sugars) were easily profiled with iEESI‐MS. Our data showed that more analytes could be detected when more energy was delivered for the desorption ionization purpose; however, heat‐sensitive analytes would not be detected once the energy input exceeded the dissociation barriers of the analytes. For the later cases, soft ionization methods such as iEESI were recommended to sensitively profile the bioanalytes of high polarity. Copyright © 2017 John Wiley & Sons, Ltd.     

Screening for amphetamine and amphetamine-type drugs in doping analysis by liquid chromatography/mass spectrometry

A selective and sensitive method for the qualitative screening of urine samples for 27 amphetamine and amphetamine-type drugs in the field of doping analysis is described. The method consists of a liquid-liquid extraction with diethyl ether at pH 14 and analysis of the extracts with a LCQ-Deca mass spectrometer equipped with an atmospheric pressure chemical ionisation interface, operated in positive ionisation mode. The total run time was 15 min. All compounds were analysed in MS2 or MS3. The detection limit for all compounds was lower than 25 ng/mL except for chlorphentermine (detection limit: 250 ng/mL).     

Electrospray-assisted laser desorption/ionization mass spectrometry for direct ambient analysis of solids

A new method of electrospray-assisted laser desorption/ionization (ELDI) mass spectrometry, which combines laser desorption with post-ionization by electrospray, was applied to rapid analysis of solid materials under ambient conditions. Analytes were desorbed from solid metallic and insulating substrata using a pulsed nitrogen laser. Post-ionization produced high-quality mass spectra characteristic of electrospray, including protein multiple charging. For the first time, mass spectra of intact proteins were obtained using laser desorption without adding a matrix. Bovine cytochrome c and an illicit drug containing methaqualone were chosen in this study to demonstrate the applicability of ELDI to the analysis of proteins and synthetic organic compounds.     

Hair analysis for illicit drugs by using capillary zone electrophoresis-electrospray ionization-ion trap mass spectrometry

In forensic toxicology, hair analysis has become a well established analytical strategy to investigate retrospectively drug abuse histories. In this field, gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry are currently used, often after preliminary screening with immunoassays. However, on the basis of previous applications to pharmaceutical analysis, capillary zone electrophoresis coupled to ion trap mass spectrometry looks also highly promising. The purpose of the present work was the development of a simple and rapid CZE-MS method for sensitive and quantitative determination of the main drugs of abuse and their metabolites (namely, 6-monoacetylmorphine, morphine, amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethampthetamine (MDMA), benzoylecgonine, ephedrine and cocaine) in human hair. Hair samples (100 mg) were washed, cut and incubated overnight in 0.1 M HCl at 45 degrees C, then neutralized with NaOH and extracted by a liquid-liquid extraction method. CZE separations were carried out in a 100 cm x 75 microm (I.D.) uncoated fused silica capillary. The separation buffer was composed of 25 mM ammonium formate, pH 9.5; the separation voltage was 15 kV. Electrokinetic injections were performed at 7 kV for 30 s under field amplified sample stacking conditions. ESI-ion trap MS detection was performed in the ESI positive ionization mode using the following conditions: capillary voltage 4 kV, nebulizer gas (nitrogen) pressure 3psi, source temperature 150 degrees C and drying gas (nitrogen) flow rate 8l/min. A sheath liquid, composed of isopropanol-water (50:50, v/v) with 0.5% formic acid, was delivered at a flow rate of 4 microl/min. The ion trap MS operated in a selected ion monitoring mode (SIM) of positive molecular ions for each drug/metabolite. Collision induced fragmentation was also possible. Nalorphine was used as internal standard. Under the described conditions, the separation of all compounds, except amphetamine/methamphetamine, MDA/MDMA and morphine/6-MAM was achieved in 20 min, with limits of detection lower than the most severe cut-offs adopted in hair analysis (i.e. 0.1 ng/mg). Linearity was assessed within drug concentration ranges from 0.025 to 5 ng of each analyte/mg of hair. Analytical precision was fairly acceptable with RSD's < or = 3.06% for migration times and < or = 22.47% for areas in real samples, in both intra-day and day-to-day experiments. On these grounds, the described method can be proposed for rapid, selective and accurate toxicological hair analysis for both clinical and forensic purposes.     

Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry

Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully.