Analytical and Bioanalytical Chemistry (v.405, #30)
Thanks to reviewers in 2013 (9597-9608).
The use of digital technology in the class and laboratory by Christopher R. Harrison (9609-9614).
is an Assistant Professor in the Department of Chemistry & Biochemistry at San Diego State University. His research focus is principally on capillary electrophoretic separations, with objectives of furthering our understanding and control of capillary electrophoretic separations and applying these principles to the development of new test for the detection of doping in athletes.
The analytical challenges of anti-doping analysis by Christopher R. Harrison (9615-9616).
is an Assistant Professor in the Department of Chemistry and Biochemistry at San Diego State University. His research focus is on the application of capillary electrophoresis to the development of new anti-doping methods. His specific anti-doping research focus, supported by World Anti-Doping Agency grants, is on the identification of blood doping methods, specifically autologous blood transfusions.
Circulating miRNAs: a new generation of anti-doping biomarkers by Nicolas Leuenberger; Neil Robinson; Martial Saugy (9617-9623).
MicroRNAs (miRNAs) are small non-coding RNAs that regulate a variety of biological processes. Cell-free miRNAs detected in blood plasma are used as specific and sensitive markers of physiological processes and some diseases. Circulating miRNAs are highly stable in body fluids, for example plasma. Therefore, profiles of circulating miRNAs have been investigated for potential use as novel, non-invasive anti-doping biomarkers. This review describes the biological mechanisms underlying the variation of circulating miRNAs, revealing that they have great potential as a new class of biomarker for detection of doping substances. The latest developments in extraction and profiling technology, and the technical design of experiments useful for anti-doping, are also discussed. Longitudinal measurements of circulating miRNAs in the context of the athlete biological passport are proposed as an efficient strategy for the use of these new markers. The review also emphasizes potential challenges for the translation of circulating miRNAs from research into practical anti-doping applications.
Keywords: Doping; Circulating microRNAs; Biomarkers; Athlete biological passport
Current strategies of blood doping detection by Torben Pottgiesser; Yorck Olaf Schumacher (9625-9639).
During the last 30 years, the artificial increase of red blood cell volume (“blood doping”) has changed the level of performance in all endurance sports. Many doping scandals have shown the extent of the problem. The detection of blood doping relies on two different approaches: the direct detection of exogenous manipulating substances (erythropoietic stimulants) or red cells (homologous transfusion) and the indirect detection, where not the doping substance or technique itself, but its effect on certain biomarkers is measured. Whereas direct detection using standard laboratory procedures such as isoelectric focusing can identify erythropoietic stimulants, homologous blood transfusion is identified through mismatches in minor blood group antigens by flow cytometry. Indirect methods such as the athlete biological passport are the only means to detect autologous transfusion and may also be used for the detection of erythropoietic stimulants or homologous transfusion. New techniques to unmask blood doping include the use of high-throughput ‘omics’ technologies (proteomics/metabolomics) and the combination of different biomarkers with the help of mathematical approaches. Future strategies should aim at improving the use of the available data and resources by applying pattern recognition algorithms to recognize suspicious athletes and, on the basis of these findings, use the appropriate testing method. Different types of information should be combined in the quest for a forensic approach to anti-doping.
Keywords: Blood doping; Erythropoietin; Blood transfusion; Athlete biological passport; Doping detection
PCR-based detection of gene transfer vectors: application to gene doping surveillance by Irene C. Perez; Caroline Le Guiner; Weiyi Ni; Jennifer Lyles; Philippe Moullier; Richard O. Snyder (9641-9653).
Athletes who illicitly use drugs to enhance their athletic performance are at risk of being banned from sports competitions. Consequently, some athletes may seek new doping methods that they expect to be capable of circumventing detection. With advances in gene transfer vector design and therapeutic gene transfer, and demonstrations of safety and therapeutic benefit in humans, there is an increased probability of the pursuit of gene doping by athletes. In anticipation of the potential for gene doping, assays have been established to directly detect complementary DNA of genes that are top candidates for use in doping, as well as vector control elements. The development of molecular assays that are capable of exposing gene doping in sports can serve as a deterrent and may also identify athletes who have illicitly used gene transfer for performance enhancement. PCR-based methods to detect foreign DNA with high reliability, sensitivity, and specificity include TaqMan real-time PCR, nested PCR, and internal threshold control PCR.
Keywords: Nested PCR; Real-time PCR; Erythropoietin; Gene transfer; Internal threshold control PCR; Vector
Targeting prohibited substances in doping control blood samples by means of chromatographic–mass spectrometric methods by Mario Thevis; Andreas Thomas; Wilhelm Schänzer (9655-9667).
Urine samples have been the predominant matrix for doping controls for several decades. However, owing to the complementary information provided by blood (as well as serum or plasma and dried blood spots (DBS)), the benefits of its analysis have resulted in continuously increasing appreciation by anti-doping authorities. On the one hand, blood samples allow for the detection of various different methods of blood doping and the abuse of erythropoiesis-stimulating agents (ESAs) via the Athlete Biological Passport; on the other hand, targeted and non-targeted drug detection by means of chromatographic–mass spectrometric methods represents an important tool to increase doping control frequencies out-of-competition and to determine drug concentrations particularly in in-competition scenarios. Moreover, blood analysis seldom requires in-depth knowledge of drug metabolism, and the intact substance rather than potentially unknown or assumed metabolic products can be targeted. In this review, the recent developments in human sports drug testing concerning mass spectrometry-based techniques for qualitative and quantitative analyses of therapeutics and emerging drug candidates are summarized and reviewed. The analytical methods include both low and high molecular mass compounds (e.g., anabolic agents, stimulants, metabolic modulators, peptide hormones, and small interfering RNA (siRNA)) determined from serum, plasma, and DBS using state-of-the-art instrumentation such as liquid chromatography (LC)–high resolution/high accuracy (tandem) mass spectrometry (LC-HRMS), LC–low resolution tandem mass spectrometry (LC-MS/MS), and gas chromatography–mass spectrometry (GC-MS).
Keywords: Doping; Sport; Mass spectrometry; Anabolic steroids; Hematide
Insulin-like growth factor-I (IGF-I) misuse in athletes and potential methods for detection by Nishan Guha; David A. Cowan; Peter H. Sönksen; Richard I. G. Holt (9669-9683).
To athletes, insulin-like growth factor-I (IGF-I) is an attractive performance-enhancing drug, particularly as an alternative to growth hormone (GH) because IGF-I mediates many of the anabolic actions of GH. IGF-I has beneficial effects on muscle protein synthesis and glycogen storage that could enhance performance in several sporting disciplines. Recombinant human IGF-I (rhIGF-I) is used in clinical practice, but a variety of IGF-I compounds and IGF-I analogues are also advertised on the internet and many have been available on the black market for several years. Although methods for detecting GH misuse are now well established and there have been several cases in which athletes have tested positive for GH, no test is yet in place for detecting IGF-I misuse. The GH-2004 research group has been investigating methods for detection of IGF-I misuse and a test is being developed on the basis of the principles of the successful GH-2000 marker method, in which markers from the IGF axis and markers of collagen and bone turnover are used to detect GH misuse. Commercial immunoassays for these markers have been validated for anti-doping purposes but new methods, including IGF-I measurement by use of mass spectrometry, should improve the performance of the tests and help in the detection of athletes who are doping with these peptide hormones. Figure Potential serum markers of IGF-I misuse. rhIGF-I/rhIGFBP-3 administration for 28 days caused an increase in serum IGF-I, P-III-NP and IGFBP-2 and decrease in serum IGF-II and ALS in recreational athletes
Keywords: IGF-I; Growth hormone; Doping
Detection of EPO injections using a rapid lateral flow isoform test by M. Lönnberg; C. Lundby (9685-9691).
Misuse of recombinant human erythropoietin (rhEPO) is a major concern in competitive sports, and the implementation of tests allowing for higher detection rates than what current tests are capable of is required. In this study, a novel lateral flow EPO isoform test kit, EPO WGA MAIIA, is evaluated on the basis of plasma and urine samples obtained from eight healthy males in connection with a 28-day rhEPO injection period. rhEPO was injected every other day during the first 14 days of the study, and the method proved to be 100 % effective in detecting rhEPO in the concomitantly obtained samples. Seven days after the last injection, three positive (>99.99 % confidence limit (CL)) subjects were found. When using 99 % CL as the cut-off limit, six of the eight subjects (75 %) were found to be suspected of doping. Samples obtained 14 and 21 days after the last injection showed no detectable trace of rhEPO. A previous study using indirect methods to determine EPO doping on the same samples indicated only that two of the subjects had suspicious values 7–21 days after the last injection. We propose implementing the easy to-use EPO WGA MAIIA test as an initial screening procedure in anti-doping work to (1) increase the detection rate of potential rhEPO doping athletes and (2) allow for a 10- to 20-fold higher analytical rate than what is possible today. Fig The lateral flow isoform test, in a dipstick format, can distinguish different types of EPO (blue balls) due to the interaction of their glycosylated structures with the lectin wheat germ agglutinin (WGA), which is the 1st zone to pass. EPO that have succeeded to pass the WGA zone will be captured by EPO-specific antibodies found in the subsequent zone. The percentage of passed EPO is calculated by also measuring the total amount of EPO in the sample using a dipstick with inactive WGA zone.
Keywords: Epoetin beta; Erythropoietin; IEF; WGA affinity chromatography
A DNA-based method for detecting homologous blood doping by Irina Manokhina; James L Rupert (9693-9701).
Homologous (or allogeneic) blood doping, in which blood is transferred from a donor into a recipient athlete, is the easiest, cheapest, and fastest way to increase red cell mass (hematocrit) and therefore the oxygen-carrying capacity of the blood. Although thought to have been rendered obsolete as a doping strategy by the increased use of rhEPO to increased hematocrits, there is evidence that athletes are still using this potentially dangerous method to improve endurance performance. Current testing for homologous blood doping is based on identification of mixed populations of red blood cells by flow cytometry. This paper proposes that homologous blood doping could also be tested for by high-resolution qPCR-based genotyping and demonstrates that assays could be developed that would detect second populations of cells even if the “donor” blood was depleted of 99 % of the DNA-containing leukocytes. Issues of test specificity and sensitivity are discussed as well as some of the ethical considerations that would have to be addressed if athletes’ genotypes were to be used by the anti-doping authorities to prevent, or detect, the use of prohibited ergogenic practices.
Keywords: Blood doping; Genotyping; Polymorphisms; Doping control
Quantification of AICAR-ribotide concentrations in red blood cells by means of LC-MS/MS by Andreas Thomas; Matthias Vogel; Thomas Piper; Oliver Krug; Simon Beuck; Wilhelm Schänzer; Mario Thevis (9703-9709).
AICAR (5-amino-4-imidazolecarboxyamide ribonucleoside) arguably provides performance-enhancing properties even in the absence of physical exercise and, therefore, the substance is banned in elite sports since 2009. Due to the natural presence of AICAR in human blood and urine, uncovering the misuse by direct qualitative analysis is not possible. Entering the circulation, the riboside is immediately incorporated into red blood cells (RBCs) and transformed into the corresponding ribotide (5′-monophosphate) form. Within the present study, an analytical method was developed to determine AICAR-ribotide concentrations in RBC concentrates by means of liquid chromatography-tandem mass spectrometry. The method was validated enabling quantitative result interpretation considering the parameters specificity, precision (intra- and interday), linearity, recovery, accuracy (LOD/LOQ), stability and ion suppression. By analysing 99 RBC samples of young athletes, normal physiological levels of AICAR-ribotide were determined (10–500 ng/mL), and individual levels were found to be stable for several days. Employing in vitro incubation experiments with AICAR riboside in fresh whole blood samples, the ribotide concentrations were observed to increase significantly within 30 min from baseline to 1–10 μg/mL. These levels are considered conserved for the lifetime of the erythrocyte and, thus, the results of the in vitro model strongly support the hypothesis that measuring abnormally high AICAR-ribotide concentrations in RBC of elite athletes has the potential to uncover the misuse of this substance for a long period of time.
Keywords: Sport; Doping; Mass spectrometry; Erythrocyte
Detection and elimination profile of cathinone in equine after norephedrine (Propalin®) administration using a validated liquid chromatography–tandem mass spectrometry method by Rong Yi; Sarah Zhao; Geoffrey Lam; Jasmeet Sandhu; Devan Loganathan; Barbara Morrissey (9711-9722).
Cathinone is the principal psychostimulant present in the leaves of khat shrub, which are widely used in East Africa and the Arab peninsula as an amphetamine-like stimulant. Cathinone readily undergoes metabolism in vivo to form less potent cathine and norephedrine as the metabolites. However, the presence of cathine and norephedrine in biological fluids cannot be used as an indicator of cathinone administration. The metabolism of pseudoephedrine and ephedrine, commonly used in cold and allergy medications, also produces cathine and norephedrine, respectively, as the metabolites. Besides, cathine and norephedrine may also originate from the ingestion of nutritional supplemental products containing extracts of Ephedra species. In Canada, ephedrine and norephedrine are available for veterinary use, whereas cathinone is not approved for human or veterinary use. In this article, the detection of cathinone in equine after administration of norephedrine is reported. To the best of our knowledge, this is the first such report in any species where administration of norephedrine or ephedrine generates cathinone as the metabolite. This observation is quite significant, because in equine detection of cathinone in biological fluids could be due to administration of the potent stimulant cathinone or the nonpotent stimulant norephedrine. A single oral dose of 450 mg norephedrine was administered to four Standardbred mares. Plasma and urine samples were collected up to 120 h after administration. The amount of cathinone and norephedrine detected in post administration samples was quantified using a highly sensitive, specific, and validated liquid chromatography–tandem mass spectrometry method. Using these results, we constructed elimination profiles for cathinone and norephedrine in equine plasma and urine. A mechanism that generates a geminal diol as an intermediate is postulated for this in vivo conversion of norephedrine to cathinone. Cathinone was also detected in samples collected after a single intramuscular administration of 200 mg ephedrine and oral administration of 300 mg ephedrine in equine. Figure Electron density structure of cathinone
Keywords: Cathinone; Equine; Ephedrine; Metabolism; Elimination; High-performance liquid chromatography–tandem mass spectrometry
Determination of cocaine and methadone in urine samples by thin-film solid-phase microextraction and direct analysis in real time (DART) coupled with tandem mass spectrometry by Angel Rodriguez-Lafuente; Fatemeh S. Mirnaghi; Janusz Pawliszyn (9723-9727).
The use of thin-film solid-phase microextraction (SPME) as the sampling preparation step before direct analysis in real time (DART) was evaluated for the determination of two prohibited doping substances, cocaine and methadone, in urine samples. Results showed that thin-film SPME improves the detectability of these compounds: signal-to-blank ratios of 5 (cocaine) and 13 (methadone) were obtained in the analysis of 0.5 ng/ml in human urine. Thin-film SPME also provides efficient sample cleanup, avoiding contamination of the ion source by salt residues from the urine samples. Extraction time was established in 10 min, thus providing relatively short analysis time and high throughput when combined with a 96-well shaker and coupled with DART technique. Figure Schematic protocol for determination of cocaine and methadone in urine by thin-film SPME and DART-MS analysis
Keywords: DART; Doping; Thin-film SPME; Urine
Quantum dot–NBD–liposome luminescent probes for monitoring phospholipase A2 activity by Venkata R. Kethineedi; Georgeta Crivat; Matthew A. Tarr; Zeev Rosenzweig (9729-9737).
In this paper we describe the fabrication and characterization of new liposome encapsulated quantum dot–fluorescence resonance energy transfer (FRET)-based probes for monitoring the enzymatic activity of phospholipase A2. To fabricate the probes, luminescent CdSe/ZnS quantum dots capped with trioctylphosphine oxide (TOPO) ligands were incorporated into the lipid bilayer of unilamellar liposomes with an average diameter of approximately 100 nm. Incorporating TOPO capped quantum dots in liposomes enabled their use in aqueous solution while maintaining their hydrophobicity and excellent photophysical properties. The phospholipid bilayer was labeled with the fluorophore NBD C6-HPC (2-(6-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)hexanoyl-1-hexa decanoyl-sn-glycero-3-phosphocholine). The luminescent quantum dots acted as FRET donors and the NBD dye molecules acted as FRET acceptors. The probe response was based on FRET interactions between the quantum dots and the NBD dye molecules. The NBD dye molecules were cleaved and released to the solution in the presence of the enzyme phospholipase A2. This led to an increase of the luminescence of the quantum dots and to a corresponding decrease in the fluorescence of the NBD molecules, because of a decrease in FRET efficiency between the quantum dots and the NBD dye molecules. Because the quantum dots were not attached covalently to the phospholipids, they did not hinder the enzyme activity as a result of steric effects. The probes were able to detect amounts of phospholipase A2 as low as 0.0075 U mL−1 and to monitor enzyme activity in real time. The probes were also used to screen phospholipase A2 inhibitors. For example, we found that the inhibition efficiency of MJ33 (1-hexadecyl-3-(trifluoroethyl)-sn-glycero-2-phosphomethanol) was higher than that of OBAA (3-(4-octadecyl)benzoylacrylic acid).
Keywords: Quantum dots; Liposomes; FRET; Phospholipase A2
Comparison of retention behavior of oligolysine and oligoarginine in ion-pairing chromatography using heptafluorobutyric acid by Wenchun Xie; Xu Qin; Iwao Teraoka; Richard A. Gross (9739-9746).
This paper describes the retention behavior of oligolysine and oligoarginine peptides of different lengths as a function of heptafluorobutyric acid (HFBA) concentration in ion-pairing reversed-phase chromatography in isocratic elution. A mixture of oligolysine and a mixture of oligoarginine with number of amino acid residues (dp) from two to eight were conveniently prepared by one-pot protease-catalyzed synthesis. Analysis of the logarithm of the retention factor k as a function of [HFBA] for each oligopeptide component, using a closed pairing model, provided values for (1) number (n) of paired HFBA anions per peptide molecule, (2) equilibrium constant (K ip,m) for ion pairing between oligopeptides and HFBA anions, and (3) product of the phase ratio and the distribution constant of the paired oligopeptide between the mobile and stationary phases (βK d,ip). We found that βK d,ip of oligoarginine is larger compared with oligolysine having the same dp. A linear relationship was obtained for ln βK d,ip as a function of n + g · dp. By optimizing constant g separately for oligolysine and oligoarginine, we determined that g is larger for oligoarginine, in agreement with the higher hydrophobicity of arginine residues. Plotting the fraction of paired oligoarginine and oligolysine as a function of [HFBA] shows that the cooperative effect in forming ion pairs is greater for oligoarginine than oligolysine. Figure Fraction Φ of paired oligolysine (dp = 3 to 6, solid symbols and solid lines) and oligoarginine (dp = 3 to 6, open symbols and dashed lines) in the mobile phase, plotted as a function of the HFBA concentration
Keywords: Oligoarginine; Oligolysine; Ion-pairing chromatography; Hydrophobic interaction; Mass spectrometry/ICP-MS
A method for the determination of d-kynurenine in biological tissues by Xiao-Dan Wang; Kyle J. Horning; Francesca M. Notarangelo; Robert Schwarcz (9747-9754).
d-Kynurenine (d-KYN), a metabolite of d-tryptophan, can serve as the bioprecursor of kynurenic acid (KYNA) and 3-hydroxykynurenine, two neuroactive compounds that are believed to play a role in the pathophysiology of several neurological and psychiatric diseases. In order to investigate the possible presence of d-KYN in biological tissues, we developed a novel assay based on the conversion of d-KYN to KYNA by purified d-amino acid oxidase (d-AAO). Samples were incubated with d-AAO under optimal conditions for measuring d-AAO activity (100 mM borate buffer, pH 9.0), and newly produced KYNA was detected by high-performance liquid chromatography (HPLC) with fluorimetric detection. The detection limit for d-KYN was 300 fmol, and linearity of the assay was ascertained up to 300 pmol. No assay interference was noted when other d-amino acids, including d-serine and d-aspartate, were present in the incubation mixture at 50-fold higher concentrations than d-KYN. Using this new method, d-KYN was readily detected in the brain, liver, and plasma of mice treated systemically with d-KYN (300 mg/kg). In these experiments, enantioselectivity was confirmed by determining total kynurenine levels in the same samples using a conventional HPLC assay. Availability of a sensitive, specific, and simple method for d-KYN measurement will be instrumental for evaluating whether d-KYN should be considered for a role in physiology and pathology.
Keywords: d-Amino acid oxidase; d-Amino acids; Kynurenic acid; Kynurenines; Schizophrenia
The rapid identification and quantification of iso-α-acids and reduced iso-α-acids in blood using UHPLC-MS/MS: validation of a novel marker for beer consumption by Luke N. Rodda; Dimitri Gerostamoulos; Olaf H. Drummer (9755-9767).
A method for the detection of iso-α-acid (IAA) type ingredient congeners that are derived from the hop plant (Humulus lupulus L.) was developed to detect recent consumption of beer in blood. Three structurally similar but chemically altered IAA, also used as beer-specific ingredients, are known as “reduced IAA”, consisting of the rho-, tetrahydro-, and hexahydro-IAA were also targeted. The use of a simple protein precipitation extraction and ultrahigh-performance liquid chromatography system coupled with a tandem mass spectrometer system enabled detection of these analytes in both antemortem and postmortem blood. Extracts were injected onto a C18 solid-core column under gradient elution to achieve separation of isobaric analogs and isomers within a 10-min run time. Electrospray ionization in negative multiple reaction monitoring mode was used to monitor three transitions for each of the analytes that were ultimately grouped together to form a calibration curve for quantification of each of the four IAA groups. The method was fully validated according to international guidelines that included extraction efficiency, matrix effects, process efficiency, ion suppression/enhancement of co-eluting analytes, selectivity, crosstalk, accuracy and precision, stabilities, and lower limits of quantification. Finally, applicability of the method described was demonstrated by the detection of IAA ingredient congeners in the blood of a volunteer following the consumption of a relatively small amount of beer in a pilot study. Fig. a Botanical illustration of Humulus lupulus (L). By permission of Puple Sage Botanicals
Keywords: Alcohol congener analysis; Beer; Ingredient congener; Hop-derived iso-α-acids; UHPLC-MS/MS; Validation
Deposition of JWH-018, JWH-073 and their metabolites in hair and effect of hair pigmentation by Jihyun Kim; Sanghwan In; Yuran Park; Meejung Park; Eunmi Kim; Sooyeun Lee (9769-9778).
Analysis of drugs in hair is often used as a routine method to obtain detailed information about drug ingestion. However, few studies have been conducted on deposition of synthetic cannabinoids and metabolites in hair. The first purpose of this study was to establish and validate an analytical method for detection of JWH-018, JWH-073, and their metabolites in hair, by use of UHPLC–MS–MS, for forensic application. The second purpose was to investigate the distribution of synthetic cannabinoids metabolites in hair and the effect of hair pigmentation, by use of an animal model. For this, JWH-073 was chosen as a representative synthetic cannabinoid. Finally, the developed method was applied to hair samples from 18 individuals suspected of synthetic cannabinoids use. JWH-018, JWH-073, and their metabolites were extracted from hair with methanol. The extract was then filtered and analyzed by UHPLC–MS–MS with an electrospray ion source in positive-ionization mode. Validation proved the method was selective, sensitive, accurate, and precise, with acceptable linearity within the calibration ranges. No significant variations were observed when different sources of both human and rat hair were used. The animal study demonstrated that JWH-073 N-COOH M was the major metabolite of JWH-073 in rat hair, and hair pigmentation did not have a significant effect on incorporation of JWH-073 and its metabolites into hair. In the analysis of 18 authentic hair samples, only JWH-018, JWH-018 N-5-OH M, and JWH-073 were detected, with wide variation in concentrations.
Keywords: Synthetic cannabinoids; JWH-018; JWH-073; Drug abuse; Hair analysis; UHPLC–MS–MS
Qualitative metabolism assessment and toxicological detection of xylazine, a veterinary tranquilizer and drug of abuse, in rat and human urine using GC–MS, LC–MS n , and LC–HR-MS n by Golo M. J. Meyer; Hans H. Maurer (9779-9789).
Xylazine is used in veterinary medicine for sedation, anesthesia, and analgesia. It has also been reported to be misused as a horse doping agent, a drug of abuse, a drug for attempted sexual assault, and as source of accidental or intended poisonings. So far, no data concerning human metabolism have been described. Such data are necessary for the development of toxicological detection methods for monitoring drug abuse, as in most cases the metabolites are the analytical targets. Therefore, the metabolism of xylazine was investigated in rat and human urine after several sample workup procedures. The metabolites were identified using gas chromatography (GC)–mass spectrometry (MS) and liquid chromatography (LC) coupled with linear ion trap high-resolution multistage MS (MS n ). Xylazine was N-dealkylated and S-dealkylated, oxidized, and/or hydroxylated to 12 phase I metabolites. The phenolic metabolites were partly excreted as glucuronides or sulfates. All phase I and phase II metabolites identified in rat urine were also detected in human urine. In rat urine after a low dose as well as in human urine after an overdose, mainly the hydroxy metabolites were detected using the authors’ standard urine screening approaches by GC–MS and LC–MS n . Thus, it should be possible to monitor application of xylazine assuming similar toxicokinetics in humans. Figure Reconstructed high-resolution mass chromatograms indicating xylazine and its phase I metabolites as well as the mass spectra with structures of xylazine and one of its hydroxy metabolites
Keywords: Xylazine; Metabolism; Human; Detectability; Gas chromatography–mass spectrometry; Liquid chromatography–multistage mass spectrometry; Liquid chromatography–high-resolution multistage mass spectrometry
Comparison of cannabinoid concentrations in oral fluid and whole blood between occasional and regular cannabis smokers prior to and after smoking a cannabis joint by Marie Fabritius; Haithem Chtioui; Giovanni Battistella; Jean-Marie Annoni; Kim Dao; Bernard Favrat; Eleonora Fornari; Estelle Lauer; Philippe Maeder; Christian Giroud (9791-9803).
A cross-over controlled administration study of smoked cannabis was carried out on occasional and heavy smokers. The participants smoked a joint (11 % Δ9-tetrahydrocannabinol (THC)) or a matching placebo on two different occasions. Whole blood (WB) and oral fluid (OF) samples were collected before and up to 3.5 h after smoking the joints. Pharmacokinetic analyses were obtained from these data. Questionnaires assessing the subjective effects were administered to the subjects during each session before and after the smoking time period. THC, 11-hydroxy-THC (11-OH-THC) and 11-nor-9-carboxy-THC (THCCOOH) were analyzed in the blood by gas chromatography or liquid chromatography (LC)-tandem mass spectrometry (MS/MS). The determination of THC, THCCOOH, cannabinol (CBN), and Δ9-tetrahydrocannabinolic acid A (THC-A) was carried out on OF only using LC-MS/MS. In line with the widely accepted assumption that cannabis smoking results in a strong contamination of the oral cavity, we found that THC, and also THC-A, shows a sharp, high concentration peak just after smoking, with a rapid decrease in these levels within 3 h. No obvious differences were found between both groups concerning THC median maximum concentrations measured either in blood or in OF; these levels were equal to 1,338 and 1,041 μg/L in OF and to 82 and 94 μg/L in WB for occasional and heavy smokers, respectively. The initial WB THCCOOH concentration was much higher in regular smokers than in occasional users. Compared with the occasional smokers, the sensation of confusion felt by the regular smokers was much less while the feeling of intoxication remained almost unchanged. Figure Time profiles of THC, 11-OH-THC, and THCCOOH in whole blood for occasional (a) and heavy cannabis smokers (b)
Keywords: Cannabis; Pharmacokinetic; Oral fluid; Whole blood; Heavy use; Occasional use
Determination of ecgonine and seven other cocaine metabolites in human urine and whole blood by ultra-high-pressure liquid chromatography–quadrupole time-of-flight mass spectrometry by Lingjuan Xiong; Rong Wang; Chen Liang; Fangqi Cao; Yulan Rao; Xin Wang; Libo Zeng; Chunfang Ni; Haiying Ye; Yurong Zhang (9805-9816).
Ecgonine is suggested to be a promising marker of cocaine (COC) ingestion. A combined mass spectrometry (MS) and tandem MS (MS/MS) method was developed to simultaneously determine ecgonine and seven other metabolites of cocaine in human urine and whole blood with ultra-high-pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The compounds were extracted from as little as 100 μL of sample by solid-phase extraction with a 96-well μElution solid-phase extraction plate. The protonated molecules or fragment ions at accurate mass acquired in MS mode were used to quantify specific analytes, following by dedicated MS/MS identification. The assay was linear in the range from 5 to 50-100 ng/mL for urine samples, except for ecgonine methyl ester (10-200 ng/mL) and ecgonine (40-400 ng/mL), and was linear from 1-2 to 50 ng/mL for whole blood samples, except for ecgonine methyl ester (20-1,000 ng/mL) and ecgonine (40-2,000 ng/mL). The correlation coefficients were all greater than 0.99. The limits of detection ranged from 0.2 to 16 ng/mL, and the lower limits of quantification ranged from 1 to 40 ng/mL. The repeatability and intermediate precision were 18.1 % or less. The accuracy was in the range from 80.0 to 122.9 %, process efficiencies were in the range from 8.6 to 177.4 %, matrix effects were in the range from 28.7 to 171.0 %, and extraction recoveries were in the range from 41.0 to 114.3 %, except for ecgonine (12.8 % and 9.3 % at low and high concentrations, respectively). This method was highly sensitive in comparison with previously published methods. The validated method was successfully applied to the analysis of real samples derived from forensic cases, and the results verified that, on the basis of data from four positive samples, ecgonine is a promising marker of cocaine ingestion. Figure Procedure for the determination of ecgonine and seven other cocaine metabolites in human urine and whole blood using a combined mass spectrometry and tandem MS method aIer the solid‐phase extraction of the anaytes
Keywords: Ecgonine; Cocaine metabolites; 96-well μElution solid-phase extraction plate; Ultra-high-pressure liquid chromatography; Quadrupole time-of-flight mass spectrometry
Development and validation of a microfluidic chip-based nano-liquid chromatography–triple quadrupole tandem mass spectrometry method for a sensitive and reliable quantification of 7-ethyl-10-hydroxycamptothecin (SN38) in mouse plasma by Gang Ahn; Dong Min Park; Jun Won Park; Joo-Youn Cho; Su-jin Rhee; Hyo-Young Kim; Dae-Seung Lee; In-Jin Jang; Hark Kyun Kim (9817-9824).
There is an increasing need for more sensitive analytical methods in pharmacokinetic studies, for example, for phase 0 clinical trials. A novel HPLC Chip–triple quadrupole mass spectrometer method (HPLC Chip-MS/MS method) for the quantification of 7-ethyl-10-hydroxycamptothecin (SN38) was developed, validated, and employed to the pharmacokinetic analysis of SN38 in ICR mice. Protein precipitation with a ratio of plasma/acetonitrile of 1:10 was chosen as the sample processing method. The nano-electrospray inserted in the microfluidic chip operated in positive mode, and selected reaction monitoring was used for quantification. Our bioanalytical method met all essential validation parameters—selectivity, accuracy, precision, dilution integrity, calibration curve, matrix effect, recovery, and different stability tests (benchtop, freeze–thaw, autosampler stability). The calibration curves (weight 1/x 2) were linear for the range 50–10,000 pg/mL. Clogging was not observed until the end of the lifetime of the microfluidic chip (350–400 injections), and carryover was practically eliminated through the introduction of a step gradient elution program. After intraperitoneal injection of 0.1 mg/kg irinotecan, SN38 concentration could be measured up to 6 h with accuracy and precision. Thus, we developed a new, very sensitive HPLC Chip-MS/MS method for the determination of plasma SN38 that has been validated in compliance with guidelines from different regulation authorities. Figure ᅟ
Keywords: Nano-liquid chromatography–triple quadrupole mass spectrometer; HPLC chip; Microfluidic chip; Bioanalytical method validation; Pharmacokinetic evaluation
Embedded passivated-electrode insulator-based dielectrophoresis (EπDEP) by Tyler Shake; Phillip Zellner; Ali Sahari; Maria V. Riquelme Breazeal; Bahareh Behkam; Amy Pruden; Masoud Agah (9825-9833).
Here, we introduce a new technique called embedded passivated-electrode insulator-based dielectrophoresis (EπDEP) for preconcentration, separation, or enrichment of bioparticles, including living cells. This new method combines traditional electrode-based DEP and insulator-based DEP with the objective of enhancing the electric field strength and capture efficiency within the microfluidic channel while alleviating direct contact between the electrode and the fluid. The EπDEP chip contains embedded electrodes within the microfluidic channel covered by a thin passivation layer of only 4 μm. The channel was designed with two nonaligned vertical columns of insulated microposts (200 μm diameter, 50 μm spacing) located between the electrodes (600 μm wide, 600 μm horizontal spacing) to generate nonuniform electric field lines to concentrate cells while maintaining steady flow in the channel. The performance of the chip was demonstrated using Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial pathogens in aqueous media. Trapping efficiencies of 100 % were obtained for both pathogens at an applied AC voltage of 50 V peak-to-peak and flow rates as high as 10 μl/min.
Keywords: Dielectrophoresis (DEP); Escherichia coli (E. coli); Staphylococcus aureus (S. aureus); Microfluidic; Microfabrication; Insulator-based dielectrophoresis (iDEP)
N-Glycosidase treatment with 18O labeling and de novo sequencing argues for flagellin FliC glycopolymorphism in Pseudomonas aeruginosa by Arbia Khemiri; Bertrand Naudin; Xavier Franck; Philippe Chan Tchi Song; Thierry Jouenne; Pascal Cosette (9835-9842).
In prokaryote organisms, N-glycosylation of proteins is often correlated to cell–cell recognition and extracellular events. Those glycoproteins are potential targets for infection control. To date, many surface-glycosylated proteins from bacterial pathogens have been described. However, N-linked Pseudomonas surface-associated glycoproteins remain underexplored. We report a combined enrichment and labeling strategy to identify major glycoproteins on the outside of microorganisms. More precisely, bacteria were exposed to a mix of biotinylated lectins able to bind with glycoproteins. The latter were then recovered by avidin beads, digested with trypsin, and submitted to mass spectrometry. The targeted mixture of glycoproteins was additionally deglycosylated in the presence of H2 18O to incorporate 18O during PNGase F treatment and were also analyzed using mass spectrometry. This approach allowed us to identify a few tens of potential N-glycoproteins, among which flagellin FliC was the most abundant. To detect the possible sites of FliC modifications, a de novo sequencing step was also performed to discriminate between spontaneous deamidation and N-glycan loss. This approach led to the proposal of three potential N-glycosylated sites on the primary sequence of FliC: N26, N69, and N439, with two of these three asparagines belonging to an N-X-(S/T) consensus sequence. These observations suggest that flagellin FliC is a heterogeneous protein mixture containing both O- and N-glycoforms. Figure Analytical scenario developed for bacterial glycoprotein enrichment. This strategy includes three main steps: (1) exposure of Pseudomonas aeruginosa cells to a mixture of biotinylated lectins [wheat germ agglutinin (WGA) and concanavalin A (ConA)]; (2) enrichment of N-glycoproteins by elution with avidin beads; and (3) mass spectrometry (MS) identification and characterization of intact and deglycosylated peptides before and after H2 18O PNGase F enzymatic treatment, respectively
Keywords: Pseudomonas aeruginosa ; Flagellin; Glycosylation; N-linked glycans
Comparative direct infusion ion mobility mass spectrometry profiling of Thermus thermophilus wild-type and mutant ∆cruC carotenoid extracts by Timo D. Stark; Angel Angelov; Mathias Hofmann; Wolfgang Liebl; Thomas Hofmann (9843-9848).
The major carotenoid species isolated from the thermophilic bacterium Thermus thermophilus HB27 have been identified as zeaxanthin–glucoside–fatty acid esters (thermozeaxanthins and thermobiszeaxanthins). Most of the genes of the proposed T. thermophilus carotenoid pathway could be found in the genome, but there is less clarity about the genes which encode the enzymes performing the final carotenoid glycosylation and acylation steps. To get a further insight into the biosynthesis of thermo(bis)zeaxanthins in T. thermophilus, we deleted the megaplasmid open reading frame TT_P0062 (termed cruC) by both exchanging it with a kanamycin resistance cassette (ΔcruC:kat) and by generating a markerless gene deletion strain (ΔcruC). A fast and efficient electrospray ionization–ion mobility–time-of-flight mass spectrometry method via direct infusion was developed to compare the carotenoid profiles of wild type and mutant T. thermophilus cell culture extracts. These comparisons revealed significant alterations in the carotenoid composition of the ΔcruC mutant, which was found to accumulate zeaxanthin. This is the first experimental evidence that the ORF encodes the glycosyltransferase enzyme necessary for the glycosylation of zeaxanthin in the final modification steps of the thermozeaxanthin biosynthesis in T. thermophilus HB27. Also, the proposed method for direct determination of carotenoid amounts and species in crude acetone extracts represents an improvement over existing methods in terms of speed and sensitivity and may be applicable in high-throughput analyses of other terpenoids as well as other important bacterial metabolites like fatty acids and their derivatives. Figure ᅟ
Keywords: ESI–IM–TOFMS; Thermozeaxanthins; Ion mobility separation; Thermus thermophilus ; Carotenoids
A multiplex, bead-based array for profiling plant-derived components in complex food matrixes by Elena Ponzoni; Diego Breviario; Alessandro Mautino; Silvia Gianì; Laura Morello (9849-9858).
Authentication of processed food ingredients is becoming an important issue for customers, and some DNA-based analytical methods have been developed, especially for animal products. As food products typically contain several different ingredients, a current challenge is to increase the multiplexing capacity of DNA-based methods, to develop “all-in-one” assays. Oligonucleotide-coupled, bead-based suspension arrays are sensitive and reproducible multiplex analytical tools. We applied the Multi-Analyte Profile (xMAP™) technology to develop an assay able to concurrently detect five different plant components in mixed flours and in processed feed and food. Capture probes were targeted to species-specific DNA polymorphisms present within the first intron of plant β-tubulin genes, which can be amplified by the tubulin-based polymorphism-amplification method (TBP-PCR). The workflow is very simple and straightforward, consisting of a PCR amplification step with universal primers, followed by the direct hybridization assay. Results are highly reproducible. For each single plant species, the absolute detection limit was as low as one target DNA copy. In complex mixtures of flours derived from seeds or from commercial dry “pasta,” relative limits of detection ranged, in weight, from 2 % for soybean to less than 0.5 % for wheat. The specificity of the capture probes and the high sensitivity of the method allowed the successful determination of the analytical composition of three feeds as well as eleven food samples, such as snacks, biscuits, and pasta. The multiplexing ability of the assay (up to 100 different analytes) provides scalability and flexibility, in response to specific needs.Schematic representation of the four-step assay for the determination of plant-derived components in food samples Figure ᅟ
Keywords: xMAP™ technology; Food traceability; Intron; TBP
Increased sensitivity of lateral flow immunoassay for ochratoxin A through silver enhancement by L. Anfossi; F. Di Nardo; C. Giovannoli; C. Passini; C. Baggiani (9859-9867).
Silver nucleation on gold has been exploited for signal amplification and has found application in several qualitative and quantitative bio-sensing techniques, thanks to the simplicity of the method and the high sensitivity achieved. Very recently, this technique has been tentatively applied to improve the performance of gold-based immunoassays. In this work, the exploitation of the signal amplification due to silver deposition on gold nanoparticles has been first applied to a competitive lateral flow immunoassay (LFIA). The signal enhancement due to silver allowed us to strongly reduce the amount of the competitor and of specific antibodies employed to build an LF device for measuring ochratoxin A (OTA), thus permitting the attainment of a highly sensitive assessment of OTA contamination, with a sensitivity gain of more than 10-fold compared to the gold-based LFIA that used the same immunoreagents and to all previously reported LFIA for measuring OTA. In addition, a less sensitive “quantitative” LFIA could be established, by suitably tuning competitor and antibody amounts, which was characterized by reproducible and accurate OTA determinations (RSD% 6–12 %, recovery% 82–117 %). The quantitative system allowed a reliable OTA quantification in wines and grape musts at the microgram per liter level requested by the European legislation, as demonstrated by a highly results obtained through the quantitative silver-enhanced LFIA and a reference HPLC-FLD on 30 samples. Figure The silver enhanced-Lateral Flow ImmunoAssay: strip development based on gold-nanoparticles occurs, followed by the addition of the enhancing solution, which causes the lines to turn black and become more intense, thus increasing detectability.
Keywords: Immunochromatographic assay; Silver nanoparticles; Mycotoxins; Food analysis
Analysis of free and bound phenolics in wine and grapes by GC–MS after automated SPE by David Allen; Anh Duyen Bui; Nicole Cain; Gavin Rose; Mark Downey (9869-9877).
The results of validation of a method for the analysis of free and bound phenolics in wine and grapes are presented. Wine and grape extracts are fractionated by automated solid-phase extraction on Bond Elut PPL cartridges to give free and bound phenolic fractions. Bound fractions are subjected to acid hydrolysis, and the phenolics released are recovered by solid-phase extraction on Bond Elut PPL cartridges. The fractions are further purified by automated solid-phase extraction on Bond Elut silica cartridges. After derivatisation to form trimethylsilyl ethers, the phenolics are determined by gas chromatography–mass spectrometry with selected ion monitoring. The method is suitable for robust, high-throughput monitoring of the concentrations of phenolics that can affect the palatability of wine.
Keywords: Guaiacol; 4-Methylguaiacol; Phenolics; Solid-phase extraction; GC–MS; Selected ion monitoring; Smoke taint; Wine; Grapes
Relationship between the matrix effect and the physicochemical properties of analytes in gas chromatography by Kanju Saka; Keiko Kudo; Makiko Hayashida; Emiko Kurisaki; Hisae Niitsu; Masaru Terada; Koji Yamaguchi; Ken-ichi Yoshida (9879-9888).
The phenomenon “matrix-induced chromatographic response enhancement” (matrix effect) causes quantitative errors in gas chromatography (GC) analyses. This effect varies according to the analyte nature, matrix type and concentration, and GC-system parameters. By focusing on the physicochemical properties of analytes, a predictive model was developed for the matrix effect using quantitative structure–property relationships. Experimental values of the matrix effect were determined for 58 compounds in a serum extract obtained from solid-phase extraction as the matrix. Eight molecular descriptors were selected, and the matrix-effect model was developed by multiple linear regression. The developed model predicted values for the matrix effect without any further experimental measurements. It also indicated that the molecular polarity (particularly H-bond donors) and volume of the analyte increase the matrix effect, while hydrophobicity and increasing number of nonpolar carbon atoms in the analyte decrease the matrix effect. The model was applied to the analysis of barbiturates. The predicted values indicated that N-methylation decreases the matrix effect, and the relative predicted values were effective for the selection of an internal standard. The obtained insight into the matrix effect and the prediction data will be helpful for developing quantitative analysis strategies.
Keywords: Matrix effect; Gas chromatography; Quantitative structure–property relationship; H-bond donor