Simultaneous determination of amphetamines and ketamines in urine by gas chromatography/mass spectrometry

Rapid analysis of ketamine with in-house antibody conjugated boronic acid modified silver chip on MALDI-TOF MS measurement

An antibody conjugated boronic acid modified silver chip (ABAS ship) is fabricated as a simple, rapid, accurate, sensitive and cost-effective sample preparation method for abused drug quantification in human urine. Ketamine, one common abused drug, was applied as proof of concept for ABAS chip with high resolution matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF MS) analysis. The overall testing process required 10 min at part per billion (ppb) sensitivity level, where current drug testing method necessitated several hours with similar sensitivity. The ABAS chip manufacture process started with slide glass by way of silver mirror reaction to form silver conductive glass for further chemical conjugation. Boronic acid functional group was decorated on silver conductive glass through the formation of silver-thiol (Ag-S) bond. Anti-ketamine antibody was covalently conjugated to boronic acid modified silver conductive glass through the formation of cyclic boronate ester between the boronic acid and the cis-diol groups on the glycans of antibody, which maintain the correct orientation to maximally capture its antigen. The resulting ABAS chip were designed to specifically capture ketamine in human urine samples, that could be directly analyzed by addition of MALDI α-Cyano-4-hydroxycinnamic acid (CHCA) matrix solution. The linear dynamic range of concentration in this method was 10-500 ng/mL with coefficient of determination 0.996. The limit of detection (LOD) and limit of quantification (LOQ) were 2.0 and 7.0 ng/mL, respectively. Importantly, the proposed method allows rapid and accurate quantification of ketamine from suspects' urine samples in 10 min and small sample volume of 1 μL was required. The resulting data were consistent with traditional gas chromatography-mass spectrometry (GC-MS) analysis. Our homemade ABAS chip could thus provide a powerful tool not only for forensic science but also for most clinical diagnosis of disease as many expression antibodies for the occurrence of diverse diseases could be simply produced and purchased.

Paper-Based Electrochemical Devices for the Pharmaceutical Field: State of the Art and Perspectives

The current international pharmaceutical scenario encompasses several steps in drug production, with complex and extremely long procedures. In the last few decades, scientific research has been trying to offer valid and reliable solutions to replace or support conventional techniques, in order to facilitate drug development procedures. These innovative approaches may have extremely positive effects in the production chain, supplying fast, and cost-effective quality as well as safety tests on active pharmaceutical ingredients (APIs) and their excipients. In this context, the exploitation of electrochemical paper-based analytical devices (ePADs) is still in its infancy, but is particularly promising in the detection of APIs and excipients in tablets, capsules, suppositories, and injections, as well as for pharmacokinetic bioanalysis in real samples.

Rapid and accurate quantification of amphetamine and methamphetamine in human urine by antibody decorated magnetite nanoparticles coupled with matrix-assisted laser desorption ionization time-of-flight mass spectrometer analysis

In this study, a novel method for the simultaneous determination and accurate quantification of abused drugs in human urine was developed. Antibody conjugated boronic acid modified magnetite nanoparticles (Fe₃O₄, MNPs) were prepared for the selectively purification of illicit drugs in combination with high resolution matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF MS) analysis. Illicit drugs, amphetamine (AM) and methamphetamine (MA), were used as model analytes to demonstrate the feasibility of our strategy. Boronic acid functionalized MNPs were first prepared via one-pot synthesis to simplify and improve the efficiency of a chemical reaction. Anti-amphetamine antibody (anti-AM antibody) and anti-methamphetamine antibody (anti-MA antibody) was conjugated onto boronic acid modified MNPs, respectively, through the formation of boronate ester bond that could maintain the correct orientation to maximally capture their antigens. The capacity of antibody conjugation to boronic acid modified MNPs was at least 24 μg antibody/mg MNPs. Antibody-conjugated MNPs were designed to specifically capture AM and MA in human urine samples, both of which can be directly eluted to MALDI target plate by adding MALDI CHCA matrix solution for the following MALDI-MS analysis. The linear range of detection of the proposed method were 25-400 ng/mL and 25-1000 ng/mL with coefficients of determination between 0.9923 and 0.9997 for AM and MA, respectively. The lowest detectable concentrations of AM and MA were 1.87 and 3.75 ng/mL, respectively. More importantly, the proposed method allows rapid and accurate quantification of AM and MA from three suspects' urine samples. The obtained results are consistent with traditional GC/MS analysis. Antibody-conjugated MNPs could thus prove to be powerful tools for important applications such as forensic science, food safety and clinical diagnosis of disease.

Improved identification of multiple drugs of abuse and relative metabolites in urine samples using liquid chromatography/triple quadrupole mass spectrometry coupled with a library search

RATIONALE

Although two multiple reaction monitoring (MRM) transitions per compound are used for identification performed using liquid chromatography/triple quadrupole mass spectrometry (LC/QqQ-MS/MS), differences in identification criteria among several regulations may lead to misidentification. We demonstrated that the use of two MRM transitions and product ion spectra improves compound identification.

METHODS

The scan cycle time was reduced using time-scheduled MRM (tMRM), data-dependent product ion scanning, and dynamic exclusion. The quantification and identification performance for 13 drugs of abuse and their metabolites were evaluated.

RESULTS

Deuterated internal standards compensated for ion suppression. All analytes exhibited intra- and interday precision <12.11%, accuracy of -10.31% to +10.10%, and no carryover. The LC/QqQ-MS/MS and reference gas chromatography/MS methods were equally precise, accurate, and specific. Several regulatory organizations include two MRM transitions, their ratio, and retention time as identification criteria. In 28 samples, the relative ion ratio variation was >10% and product ion spectral matches with >94% probabilities improved drug and metabolite identification.

CONCLUSIONS

The LC/QqQ-MS/MS method is a comprehensive assay in which tMRM and the product ion scan are combined in a single run by using a QqQ mass analyzer to simultaneously quantify amphetamine, ketamine, morphine, and their relative metabolites in urine. The proposed method can be applied in forensic science.

Determination of ketamine, norketamine and dehydronorketamine in urine by hollow-fiber liquid-phase microextraction using an essential oil as supported liquid membrane

Here, we present a method for the determination of ketamine (KT) and its main metabolites, norketamine (NK) and dehydronorketamine (DHNK) in urine samples by using hollow-fiber liquid-phase microextraction (HF-LPME) in the three-phase mode. The fiber pores were filled with eucalyptus essential oil and a solution of 1.0mol/L of HCl was introduced into the lumen of the fiber (acceptor phase). The fiber was submersed in the alkalinized urine containing 10% NaCl, and the system was submitted to lateral shaking (2400rpm) during 30min. Acceptor phase was withdrawn from the fiber, dried and the residue was then derivatized with trifluoroacetic anhydride (TFAA) for further determination by gas chromatography-mass spectrometry (GC-MS). The calibration curves were linear over the specified range and limits of detection (LoDs) obtained for KT, NK and DHNK were below the cut-off value (1.0ng/mL) recommended by the United Nations Office on Drugs and Crime (UNODC). A totally "green chemistry" approach of the sample extraction was obtained by using essential oil as a supported liquid membrane in HF-LPME. The developed method was successfully validated and applied to urine samples collected from two clinical cases in which KT was suspected to be involved.

Arrays of low-temperature plasma probes for ambient ionization mass spectrometry

RATIONALE

This paper reports the development of arrays of capillary-based low-temperature plasma (LTP) probes for direct sample analysis. These probe arrays allow a higher surface area to be analyzed, increasing the throughput in large sample analysis. Validation of these arrays was performed on illicit, cathinone-based drugs marketed as 'bath salts'.

METHODS

LTP arrays consisting of 1, 7, and 19 probes were constructed with quartz capillaries and held together with silver epoxy resin adhesive. Three drugs, mephedrone, methylone and methylenedioxypyrovalerone, were analyzed with each plasma ion source and an ion trap mass spectrometer in full MS and in MS/MS positive ion mode. Chemical and thermal footprints were determined for each source. A reactive probe design was used to inject trifluoroacetic anhydride directly into the plasma stream for on-line derivatization.

RESULTS

Small LTP probes and bundled arrays provide low picogram level limits of detection for mephedrone, methylone and methylenedioxypyrovalerone. Bundling the probes together in larger arrays increases the surface area analyzed by a factor of ten, while maintaining surface temperatures below 40 °C. Selectivity towards mephedrone and methylone was increased using trifluoracetylation under ambient ionization conditions.

CONCLUSIONS

Low-temperature plasma ionization sources allow rapid detection of illicit 'bath salt' drugs in low amounts. The sources have a larger sampling area that allows faster detection of each analyte, and selectivity towards the selected drug is enhanced by adding reagents directly into the plasma stream.

Synthesis of deuterium labeled ketamine metabolite dehydronorketamine-d₄

A convenient synthesis of ketamine metabolite dehydronorketamine-d(4), starting from commercially available deuterium labeled bromochlorobenzene, was achieved. Key steps include Grignard reaction, regioselective hydroxybromination, Staudinger reduction, and dehydrohalogenation.

Study of the fragmentation pattern of ketamine-heptafluorobutyramide by gas chromatography/electron ionization mass spectrometry

Ketamine is an anaesthetic compound used in human and veterinary medicine with hallucinogen properties that have resulted in its increased illicit use by teenagers at rave parties. Although several gas chromatography/mass spectrometry (GC/MS) methods have been reported for the quantification of the drug both in urine and in hair, its electron ionization (EI) fragmentation after derivatization with different reagents has been not yet fully investigated. The present work reports the study of the fragmentation of ketamine, derivatized with heptafluorobutyric anhydride (HFBA-Ket), using gas chromatography/electron ionization mass spectrometry (GC/EI-MS). The complete characterization of the fragmentation pattern represented an intriguing exercise and required tandem mass spectrometry (MS(n)) experiments, high-resolution accurate mass measurements and the use of deuterated d(4)-ketamine to corroborate the proposed structures and to characterize the fragment ions carrying the unchanged aromatic moiety. Extensive fragmentation was observed, mainly located at the cyclohexanone ring followed by rearrangement of the fragment ions, as confirmed by the mass spectra obtained from the deuterated molecule. The GC/EI-MS analysis of HFBA-Ket will represent a useful tool in forensic science since high-throughput analyses are enabled, preserving both the GC stationary phase and the cleanliness of the mass spectrometer ion optics.

Formation of Trifluoroacetylated Ephedrine During the Analysis of a Pseudoephedrine-Formaldehyde Adduct by TFAA Derivatization Followed by GC-MS

(+)-Pseudoephedrine reacts with formaldehyde to form (4S,5S)-3,4-dimethyl-5-phenyloxazolidine. Gas chromatography-mass spectrometry (GC-MS) analysis after the reaction of this oxazolidine with excess trifluoroacetic acid anhydride (TFAA) shows predominantly N,O-bis(trifluoroacetyl)pseudoephedrine with some of the monotrifluoroacetylated derivative. In addition, variable amounts of N,O-bis(trifluoroacetyl)ephedrine were detected by GC-MS. N,O-bis(trifluoroacetyl)ephedrine was not detected upon trifluoroacetylation of the source (+)-pseudoephedrine, and nuclear magnetic resonance analysis of the (4S,5S)-3,4-dimethyl-5-phenyloxazolidine showed no evidence of the (4R,5S) isomer. This suggests that the N,O-bis(trifluoroacetyl)ephedrine is formed by epimerization during the TFAA derivatization and GC-MS analysis of the pseudoephedrine-formaldehyde adduct.

Pressure-adjusted continual flow heart-cutting for the high throughput determination of amphetamine-type stimulant drugs in whole blood by fast multidimensional gas chromatography–mass spectrometry

Innovative features and technical improvements in modern bench-top quadrupole gas chromatograph-mass spectrometer (GC-MS) have prepared the way for faster and more cost-effective applications while still maintaining sufficient chromatographic resolution, speed of MS data acquisition and reliability of analytical methodology. In this paper, a short wide-bore capillary column with low film thickness (5 m x 0.32 mm i.d., 0.1 microm) was used a pre-fractionating column and only chosen heart-cuts were transferred to the second chromatographic dimension (15 m x 0.25 mm i.d., 0.25 microm) by means of a pressure-adjusted continual flow type switching device for quantification of five common amphetamine-type stimulant drugs. The instrumental setting used, in combination with carefully optimized operational fast GC and MS parameters, markedly decreased the retention times of the targeted analytes, e.g., amphetamine 0.891 min and methamphetamine 1.037 min, and the total chromatographic runtime (1.700 min), as well as reducing the need for continuous cleaning of the MS ion source and increasing column life compared with conventional GC-MS approaches. The performance of the instrumental configuration and analytical method was evaluated in validation experiments and the method was also applied to authentic samples. The method demonstrates the potential of fast GC-MS in combination with a gas-phase microfluidic Deans switch device for analysing of (semi)volatile compounds, such as amphetamine-type stimulant (ATS) drugs. This should be particularly useful in modern laboratories aiming at cost-efficient analysis as well as the optimum use of available laboratory capacity and instrumentation.

Gas chromatography-mass spectrometry analysis of ketamine and its metabolites--a comparative study on the utilization of different derivatization groups

Method of chemical derivatization is the main difference among the GC-MS based methodologies reported for the analysis of ketamine and its major metabolites (norketamine and dehydronorketamine). These approaches included acylation and silylation resulting in the formation of acetyl, trifluoroacetyl, heptafluorobutyryl, and pentafluorobenzoyl (for acylation); and possibly trimethylsilyl and t-butyldimethylsilyl (for silylation) derivatives. This study evaluates the merits of these approaches based on the following criteria: reaction yields and ionization efficiency of the derivatization products; chromatographic characteristics; and cross-contributions to the intensities of ions designating the analyte and the internal standard. Pentafluorobenzoyl-derivatives were found to provide the best performance characteristics.

GC-MS quantification of ketamine, norketamine, and dehydronorketamine in urine specimens and comparative study using ELISA as the preliminary test methodology

An automated solid-phase extraction procedure combined with the gas chromatography-mass spectrometry (GC-MS) methodology, without derivatization, has been developed for the determination of ketamine (K), norketamine (NK), and dehydronorketamine (DHNK) in urine. The analytical approach is simple and rapid, yet reliable, achieving good linearity (r(2)>0.999 over the concentration range of 30 to 1000 ng/mL), sensitivity (limits of quantification = 15, 10, and 20 ng/mL for K, NK, and DHNK, respectively), accuracy (90-104%), and precision (RSD<8.1%) for all analytes. Two hundred and six urine specimens collected from suspected drug users were analyzed by this protocol and also screened by Neogen ELISA method to evaluate the efficiency as well as the compatibility of these two methods. Neogen ELISA showed high efficiency (98.1%), high sensitivity (90.9%), high specificity (98.9%), low false-positive rate (1.1%), and moderate false-negative rate (9.1%), adopting 10 ng/mL K as the cutoff. Neogen ELISA screening followed by GC-MS analysis appeared to be a good screening-confirmation test scheme for the analysis of K in urine. Twenty of the 22 positive urine specimens contained all three analytes simultaneously, with DHNK showing the highest and K the lowest concentrations.

Simultaneous determination of new thioamphetamine designer drugs in plasma by capillary electrophoresis coupled with mass spectrometry

A simple method for the simultaneous identification and quantification of four 2,5-methylenedioxy derivatives of 4-thioamphetamine (ALEPH series) in plasma samples was developed. The method consists of solid-phase extraction (SPE) using a Bond Elut C(18) cartridge and capillary electrophoresis coupled with electrospray ionisation mass spectrometry (CE/ESI-MS). The SPE method used required only simple steps and provided a clean extract from which identification of each drug was feasible, even at low concentrations. The method was validated according to international guidelines. The calibration curves were linear over the concentration range of 50 to 1000 ng/mL for all drugs with correlation coefficients that exceeded 0.998. The lower limits of detection of the drugs were 23-43 ng/mL. The absolute recoveries for the drugs were 64-92% and 75-96% at concentrations of 100 and 500 ng/mL, respectively. The validation data (precision, accuracy, and recovery) show the reproducibility and selectivity of the method. This clean and simple method allows the routine detection of designer drugs such as thioamphetamines which may become a serious problem in the control of illegal drugs.