Ultra-high Performance Liquid Chromatography Electrospray Research Articles

Screening for new psychoactive substances in hair by ultrahigh performance liquid chromatography–electrospray ionization tandem mass spectrometry

In the latest years, many new psychoactive substances (NPS) from several drug classes have appeared in the illicit drug market. Their rapid, sensitive and specific identification in biological fluids is hence of great concern for clinical and forensic toxicologists. Here is described a multi-analyte method for the determination of NPS, pertaining to different chemical classes (synthetic cannabinoids, synthetic cathinones, ketamine, piperazines and amphetamine-type substances—ATS) in human hair using ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) in electrospray ionization mode. We focused on a sample preparation able to extract the different classes of NPS. About 30mg of hair was decontaminated and incubated overnight under sonication in different conditions depending on the type of analytes to be extracted: (a) with 300μL of HCOOH 0.1% for cathinones, piperazines and ATS; (b) with 300μL of MeOH for synthetic cannabinoids. Ten microliter of the extracts were then injected in UHPLC–ESI–MS/MS in MRM mode. The LODs varied from 2pg/mg to 20pg/mg. The method was linear in the range from the LOQ to 500pg/mg and showed acceptable precision (%RSD<15) and accuracy (%E<15) for all the analytes. The method was finally applied on 50 samples from real forensic cases (driving license re-granting, postmortem toxicological analyses, workplace drug testing). In three samples we detected synthetic cannabinoids, in four samples cathinones or ephedrines, in two samples ketamine.

Ultrahigh‐performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry of antioxidants (amines and phenols) applied in lubricant engineering

For the qualification and quantification of antioxidants (aromatic amines and sterically hindered phenols), most of them applied as lubricant additives, two ultrahigh-performance liquid chromatography (UHPLC) electrospray ionization mass spectrometric methods applying the positive and negative ion mode have been developed for lubricant design and engineering thus allowing e.g. the study of the degradation of lubricants. Based on the different chemical properties of the two groups of antioxidants, two methods offering a fast separation (10 min) without prior derivatization were developed. In order to reach these requirements, UHPLC was coupled with an LTQ Orbitrap hybrid tandem mass spectrometer with positive and negative ion electrospray ionization for simultaneous detection of spectra from UHPLC-high-resolution (HR)-MS (full scan mode) and UHPLC-low-resolution linear ion trap MS(2) (LITMS(2)), which we term UHPLC/HRMS-LITMS(2). All 20 analytes investigated could be qualified by an UHPLC/HRMS-LITMS(2) approach consisting of simultaneous UHPLC/HRMS (elemental composition) and UHPLC/LITMS(2) (diagnostic product ions) according to EC guidelines. Quantification was based on an UHPLC/LITMS(2) approach due to increased sensitivity and selectivity compared to UHPLC/HRMS. Absolute quantification was only feasible for seven analytes with well-specified purity of references whereas relative quantification was obtainable for another nine antioxidants. All of them showed good standard deviation and repeatability. The combined methods allow qualitative and quantitative determination of a wide variety of different antioxidants including aminic/phenolic compounds applied in lubricant engineering. These data show that the developed methods will be versatile tools for further research on identification and characterization of the thermo-oxidative degradation products of antioxidants in lubricants.

Structural characterization of silicone polymers using compositional ultra-high performance liquid chromatography separation, electrospray ionization, and high resolution/accurate mass

In this article, the development of an on-line ultra-high performance liquid chromatography (UHPLC)-high resolution/accurate mass (HR/AM) methodology for timely characterization of a broad range of silicone polymers is described. Electrospray ionization was optimized for silicone polymers to enable the direct coupling of the separation with mass spectrometry. Reverse-phase UHPLC was optimized to provide a high resolution separation of oligomers by molar mass and by end-group composition. With the high resolution compositional separation, multiple pseudo-molecular ion species were indexed with retention time and assisted in rapid identification of oligomer species. Relative retention times of different oligomer end-group species separated based on polarity provided additional information to aid data interpretation. These additional pieces of information were combined with accurate mass to provide a high information content analysis in a relatively short time frame. This methodology was applied to polymer end-group characterization, as well as comparative analysis examples.

Simultaneous quantification of mycotoxins and pesticide residues in ginseng with one-step extraction using ultra-high performance liquid chromatography–electrospray ionization tandem mass spectrometry

This study describes the development and validation of a simple, accurate and sensitive ultra high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) method for the simultaneous quantification of 10 mycotoxins and 29 pesticides in ginseng. The method featured a fast and straightforward one-step extraction procedure using acetonitrile/water/formic acid (99:33:1, v/v/v) without further cleanup. Rapid LC separation in 8min was successfully achieved on a Phenomenex Kinetex C18 column (2.1mm×100mm, 2.6μm) with a flow rate of 0.30mL/min using a mobile phase of water containing 0.1% formic acid and methanol. Simultaneous acquisition was performed in the positive and negative ion modes. For some analytes, enhanced responses were acquired in negative ion mode (e.g., Zearalenone, α-Zearalenol and β-Zearalenol); however, the majority of analytes were monitored in positive ion mode with multiple reaction monitoring (MRM). Two MS/MS transitions for each analyte were acquired to ensure reliable identification and accurate quantification. The method was validated in house through linearity, selectivity, precision, and recovery studies. Analytical data were satisfactory with typical recoveries of 70-120% and relative standard deviations (RSDs) below 20%. The limits of detection (LODs) ranged from 0.01 to 0.25ng/mL, which are below the maximum residue levels (MRLs) established by European legislation for mycotoxins or pesticides in foods and foodstuffs. Forty-three ginseng samples (ginseng (n=30), American ginseng (n=6), red ginseng (n=7)) collected from Chinese markets were analyzed and the most frequently detected pesticide was chlorpyrifos with an incidence of 97% and ranged from 37.63 to 158.60μg/kg. Ion ratios, retention times and experimental Q/q ratios were also compared with those of the corresponding reference standard in order to avoid false-positive results.

Identification of Sinensetin Metabolites in Rat Urine by an Isotope-Labeling Method and Ultrahigh-Performance Liquid Chromatography–Electrospray Ionization Mass Spectrometry

Sinensetin (SIN), one of the major polymethoxyflavones (PMFs) contained mainly in the citrus peels, has been reported to possess various bioactivities, including antifungal, antimutagenic, anticancer, and anti-inflammatory activities. Although the biotransformation of SIN in fungi and insects has been reported, the information about the metabolism of SIN in mammals is still unclear. In this study, formation of SIN metabolites in rats was investigated. Four isotope-labeled SINs ([4'-D3]SIN, [3'-D3]SIN, [5-D3]SIN, and [6-D3]SIN) were synthesized and administered to rat. The urine samples were collected and main metabolites were monitored by ultrahigh-performance liquid chromatography-electrospray ionization mass spectrometry. The administered compound and four SIN metabolites were detected in rat urine. These metabolites were identified as 4'-hydroxy-5,6,7,3'-tetramethoxyflavone, 5-hydroxy-6,7,3',4'-tetramethoxyflavone, 6-hydroxy-5,7,3',4'-tetramethoxyflavone, and 7-hydroxy-5,6,3',4'-tetramethoxyflavone sulfate.

Validation of a method for simultaneous determination of nitroimidazoles, benzimidazoles and chloramphenicols in swine tissues by ultra-high performance liquid chromatography–tandem mass spectrometry

This paper presents a sensitive and confirmatory multi-residue method for the analysis of 23 veterinary drugs and metabolites belonging to three classes (nitroimidazoles, benzimidazoles, and chloramphenicols) in porcine muscle, liver, and kidney. After extracted with ethyl acetate and basic ethyl acetate sequentially, the crude extracts were defatted with hexane and further purified using Oasis MCX solid-phase extraction cartridges. Rapid determination was carried out by ultra-high performance liquid chromatography–electrospray ionization tandem mass spectrometry. Data acquisition was performed under positive and negative mode simultaneously. Recoveries based on matrix-matched calibrations for meat, liver, and kidney ranged from 50.6 to 108.1%. The method quantification limits were in the range of 3–100ng/kg.

Ultra high performance liquid chromatography–electrospray ionization–tandem mass spectrometry screening method for direct analysis of designer drugs, “spice” and stimulants in oral fluid

An ultra high performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UHPLC–ESI–MS/MS) screening method for the direct analysis in oral fluid (OF) of 24 drugs, including new synthetic cannabinoids and so-called “smart” designer drugs, in a single chromatographic run was set up. Benzylpiperazine, methylone, 5,6-methylenedioxy-2-aminoindane (MDAI), fenproporex, 4-fluoroamphetamine (4-FA), 4-methyl-N-ethylcathinone (4-MEC), 4-methylamphetamine (4-MA), methylbenzodioxolylbutanamine (MBDB), mephedrone, methylthioamphetamine (MTA), methylenedioxypyrovalerone (MDPV), mefenorex, nabilone, furfenorex, clobenzorex, JWH-200, AM 694, JWH-250, JWH-073, JWH-018, JWH-019, JWH-122, HU 210 and CP 47497 were determined in a chromatographic run of 9min only with no sample pre-treatment, after addition of ISs and dilution in mobile phase A. This method is designed to be applied to 250μL of OF sample, anyway is suitable to be used on smaller volumes (till 100μL). LODs vary from 1ng/mL to 20ng/mL. No interfering peaks were observed due to similar analytes, common therapeutic drugs or endogenous compounds. Matrix effect, although present especially for mephedrone, is acceptable, allowing the detection of the compounds at the LODs described. The developed method was applied on 400 real OF samples from on-site tests performed by police officers.

Identification of 5,7,3′,4′-Tetramethoxyflavone Metabolites in Rat Urine by the Isotope-Labeling Method and Ultrahigh-Performance Liquid Chromatography–Electrospray Ionization–Mass Spectrometry

5,7,3',4'-Tetramethoxyflavone (TMF), one of the major polymethoxyflavones (PMFs) isolated from Kaempferia parviflor , has been reported possessing various bioactivities, including antifungal, antimalarial, antimycobacterial, and anti-inflammatory activities. Although several studies on the TMF have been reported, the information about the metabolism of TMF and the structures of TMF metabolites is still not yet clear. In this study, an isotope-labeling method was developed for the identification of TMF metabolites. Three isotope-labeled TMFs (5,7,3',4'-tetramethoxy[3'-D(3)]flavone, 5,7,3',4'-tetramethoxy[4'-D(3)]flavone, and 5,7,3',4'-tetramethoxy[5,4'-D(6)]flavone) were synthesized and administered to rats. The urine samples were collected, and the main metabolites were monitored by ultrahigh-performance liquid chromatography-electrospray ionization-mass spectrometry. Five TMF metabolites were unambiguously identified as 3'-hydroxy-5,7,4'-trimethoxyflavone, 7-hydroxy-5,3',4'-trimethoxyflavone sulfate, 7-hydroxy-5,3',4'-trimethoxyflavone, 4'-hydroxy-5,7,3'-trimethoxyflavone, and 5-hydroxy-7,3',4'-trimethoxyflavone.

Development and validation of a sensitive U-HPLC–MS/MS method with electrospray ionization for quantitation of ranolazine in human plasma: Application to a clinical pharmacokinetic study

A simple, sensitive and high-throughput ultra high-performance liquid chromatography electrospray ionization mass spectrometry (U-HPLC–ESI-MS/MS) method has been developed and validated for the determination of ranolazine in human plasma. Propafenone was employed as the internal standard (I.S.). The analytes were chromatographically separated on a BEH C18 column (50mm×2.1mm, 1.7μm) with a mobile phase consisting of acetonitrile and aqueous ammonium acetate solution (0.06% formic acid, 7.5mmolL−1 ammonium acetate, 40:60, v/v). Detection of the analytes was achieved using positive ion electrospray ionization via multiple reactions monitoring mode. The mass transitions were m/z 428.3→279.3 for ranolazine and m/z 342.4→115.9 for propafenone. The assay was linear over the concentration range 1–3000ngmL−1, with correlation coefficients ≥0.997. The intra- and inter-day coefficients of variation were less than 8.9% in terms of relative standard deviation and accuracy ranged from 93.0 to 108.9% at all quality control levels. The validated method was a simple sample preparation procedure and short run-time (<2.0min) method, which was successfully applied to a phase I pharmacokinetic study of ranolazine in Chinese healthy volunteers.

Protein expression of sensory and motor nerves: Two-dimensional gel electrophoresis and mass spectrometry.

The present study utilized samples from bilateral motor branches of the femoral nerve, as well as saphenous nerves, ventral roots, and dorsal roots of the spinal cord, to detect differential protein expression using two-dimensional gel electrophoresis and nano ultra-high performance liquid chromatography electrospray ionization mass spectrometry tandem mass spectrometry techniques. A mass spectrum was identified using the Mascot search. Results revealed differential expression of 11 proteins, including transgelin, Ig kappa chain precursor, plasma glutathione peroxidase precursor, an unnamed protein product (gi|55628), glyceraldehyde-3-phosphate dehydrogenase-like protein, lactoylglutathione lyase, adenylate kinase isozyme 1, two unnamed proteins products (gi|55628 and gi|1334163), and poly(rC)-binding protein 1 in motor and sensory nerves. Results suggested that these proteins played roles in specific nerve regeneration following peripheral nerve injury and served as specific markers for motor and sensory nerves.