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Analytica Chimica Acta (v.756, #)
Sensitive electrochemical detection of hydroxyl radical with biobarcode amplification by Liang Wu; Yan Yang; Hejing Zhang; Gangbing Zhu; Xiaohua Zhang; Jinhua Chen (pp. 1-6).
.Display Omitted► A DNA-based biosensor for amplified electrochemical detection ofOH was developed. ► The sensor shows good analytical performance for sensitive detection ofOH. ► The biosensor has potential application in the evaluation of antioxidant capacity.By using biobarcode nanoparticles, we have successfully constructed a DNA-based biosensor for amplified electrochemical detection of hydroxyl radical (OH). Thiolated DNA1 (SH-DNA1) was firstly immobilized on the planar gold (Au) electrode.OH generated from Fenton reaction could induce serious oxidative damage of the DNA layer adsorbed on the electrode surface, which was monitored by an intercalating probe, methylene blue (MB). In order to enhance the sensitivity of the biosensor, DNA2-functionalized Au nanoparticles (DNA2-AuNPs) were used to amplify the response signal. The developed DNA-based biosensor could detectOH quantitatively with wide linear range up to 10mM and low detection limit of 3μM, and exhibited satisfactory selectivity. On the other hand, this electrochemical biosensor could have potential application in the evaluation of antioxidant capacity.
Keywords: DNA damage; Methylene blue; Hydroxyl radical; Fenton reaction; Biobarcode amplification
Facile synthesis of graphene hybrid tube-like structure for simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan by Wen Zhang; Yaqin Chai; Ruo Yuan; Shihong Chen; Jing Han; Dehua Yuan (pp. 7-12).
A tube-like structure of graphene hybrid (GS–PTCA) was synthesized via π–π stacking interaction, and was used as modifier to fabricate electrode for simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp). SEM images of GS, PTCA and GS–PTCA were presented. Under the synergistic effects between GS and PTCA, the modified electrode displayed high catalytic activity and selectivity toward the oxidation of AA, DA, UA, and Trp.Display Omitted► A simple strategy for simultaneous detection of AA, DA, UA and Trp has been constructed. ► The tube-like structure of graphene hybrid (GS–PTCA) was synthesized. ► The GS–PTCA provided a selective interface for discrimination of AA, DA, UA and Trp.In the present work, a tube-like structure of graphene hybrid as modifier to fabricate electrode for simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp) was reported. The hybrid was synthesized by a simple method based on graphene sheets (GS) and 3,4,9,10-perylenetetracarboxylic acid (PTCA) via π–π stacking interaction under ultrasonic condition. The combination of GS and PTCA could effectively improve the dispersion of GS, owing to PTCA with the carboxylic-functionalized interface. Comparing with pure GS or PTCA modified electrode, GS–PTCA displayed high catalytic activity and selectivity toward the oxidation of AA, DA, UA, and Trp. Moreover, cyclic voltammetry, different pulse voltammetry and scanning electron microscopy were employed to characterize the sensors. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA, and Trp were 20–420μM, 0.40–374μM, 4–544μM and 0.40–138μM, respectively, and the detection limits were 5.60μM, 0.13μM, 0.92μM and 0.06μM ( S/ N=3). Importantly, the proposed method offers promise for simple, rapid, selective and cost-effective analysis of small biomolecules.
Keywords: Graphene sheets; 3,4,9,10-Perylenetetracarboxylic acid; Ascorbic acid; Dopamine; Uric acid; Tryptophan
Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self assembling of bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid on Fe3O4@Ag core@shell nanoparticles: Characterization and application by Elham Tahmasebi; Yadollah Yamini (pp. 13-22).
Self assembling of bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid on Fe3O4@Ag core@shell nanoparticles and application of it for solid phase extraction of PAHs.Display Omitted► A novel sorbent for magnetic solid-phase extraction of PAHs was introduced. ► Silver was coated on Fe3O4 nanoparticles (MNPs) by reduction of AgNO3 with NaBH4. ► Bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid self-assembled on silver coated MNPs. ► Size, morphology, composition and properties of the nanoparticles were characterized. ► Extraction efficiency of the sorbent was investigated by extraction of five PAHs.A novel sorbent for magnetic solid-phase extraction by self-assembling of organosulfur compound, (bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid), onto the silver-coated Fe3O4 nanoparticles was introduced. Due to the formation of covalent bond of SAg, the new coating on the silver surface was very stable and showed high thermal stability (up to 320°C). The size, morphology, composition, and properties of the prepared nanoparticles have also been characterized and determined using scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX), dynamic light scattering (DLS), Fourier transform-infrared (FT-IR) spectroscopy, and thermal gravimetric analysis (TGA). Extraction efficiency of the new sorbent was investigated by extraction of five polycyclic aromatic hydrocarbons (PAHs) as model compounds. The optimum extraction conditions for PAHs were obtained as of extraction time, 20min; 50mg sorbent from 100mL of the sample solution, and elution with 100μL of 1-propanol under fierce vortex for 2min. Under the optimal conditions, the calibration curves were obtained in the range of 0.05–100μgL−1 ( R2>0.9980) and the LODs (S/N=3) were obtained in the range of 0.02–0.10μgL−1. Relative standard deviations (RSDs) for intra- and inter-day precision were 2.6–4.2% and 3.6–8.3%, respectively. In addition, feasibility of the method was demonstrated with extraction and determination of PAHs from some real samples containing tap water, hookah water as well as soil samples with relative recovery of 82.4–109.0% and RSDs of 3.5–11.6%.
Keywords: Fe; 3; O; 4; magnetic nanoparticles; Self-assembling; Bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid; Polycyclic aromatic hydrocarbons; Solid-phase extraction
A comprehensive procedure based on gas chromatography–isotope ratio mass spectrometry following high performance liquid chromatography purification for the analysis of underivatized testosterone and its analogues in human urine by Xavier de la Torre; Cristiana Colamonici; Davide Curcio; Francesco Molaioni; Francesco Botrè (pp. 23-29).
Display Omitted► Overall approach for urine samples purification by HPLC for subsequent GC/C/IRMS analysis in doping control. ► Detection of pseudo-endogenous androgenic steroids (i.e. testosterone, androstenedione) misuse in sports. ► Routine analysis of steroids by GC/C/IRMS in sports drug testing.The confirmation by GC/C/IRMS of the exogenous origin of pseudo-endogenous steroids from human urine samples requires extracts of adequate purity. A strategy based on HPLC sample purification prior to the GC/C/IRMS analysis of human urinary endogenous androgens (i.e. testosterone, androsterone and/or androstenediols), is presented. A method without any additional derivatization step is proposed, allowing to simplify the urine pretreatment procedure, leading to extracts free of interferences permitting precise and accurate IRMS analysis, without the need of correcting the measured delta values for the contribution of the derivatizing agent. The HPLC extracts were adequately combined to both reduce the number of GC/C/IRMS runs and to have appropriate endogenous reference compounds (ERC; i.e. pregnanediol, 11-keto-etiocholanolone) on each GC–IRMS run. The purity of the extracts was assessed by their parallel analysis by gas chromatography coupled to mass spectrometry, with GC conditions identical to those of the GC/C/IRMS assay. The method has been validated according to ISO17025 requirements (within assay precision below 0.3‰13C delta units and between assay precision below 0.6‰13C delta units for most of the compounds investigated) fulfilling the World Anti-Doping Agency requirements.
Keywords: Androgens; Isotope ratio mass spectrometry (IRMS); HPLC; Sample preparation; Doping in sports
RF-pulsed glow discharge time-of-flight mass spectrometry for glass analysis: Investigation of the ion source design by Marcos Bouza; Beatriz Fernández; Cristina González-Gago; Nerea Bordel; Rosario Pereiro; Alfredo Sanz-Medel (pp. 30-36).
Display Omitted► A new GD chamber coupled to TOFMS was investigated for direct glass analysis. ► The effect of GD experimental conditions on signal shapes was investigated. ► The proposed GD induced less thermal stress on samples than previous GD designs. ► Better detection limits were found compared to those obtained with previous GDs.Radiofrequency (RF) millisecond pulsed glow discharge (PGD) coupled to time-of-flight mass spectrometry (TOFMS) was investigated for direct elemental analysis of glass samples. Aiming at achieving highest elemental sensitivity, appropriate discrimination from polyatomics, and good crater shapes on glasses, a new Grimm-type GD chamber (termed from now “UNIOVI GD”, designed and constructed in our laboratory) was coupled to TOFMS, and the results compared with those obtained with the former GD design (here denominated as “GD.1”) of the initial RF-PGD-TOFMS prototype. The critical differences distinguishing the two GDs under scrutiny are the GD chamber thickness (15.5mm for the GD.1 and 7mm for the UNIOVI GD) and the “flow tube” which is inserted in the GD.1 and inexistent in UNIOVI GD.A pulse period of 4ms and a duty cycle of 50% were selected for the PGD studies. In order to characterizing the UNIOVI GD, the effect of RF-PGD experimental conditions (pressure and power) on signal shapes along the pulse was first investigated. Then, the analytical performance achieved was compared with results obtained using the GD.1 chamber. Results show that the UNIOVI GD source induced less thermal stress on the glass specimens. Consequently higher GD power can be applied to the UNIOVI GD (up to at least 130W), as compared to the GD.1 (maximum of 60W), without glass sample breakdown. Also, better crater shapes on samples were obtained using the UNIOVI GD. Moreover, the detection limits attained with the UNIOVI GD (in the range of μgg−1) were in most cases about one order of magnitude better for the analytes investigated (B, Na, Al, Si, Mn, Ni, Co, Cu, Zn, As, Sr, Ag, In, Sn, Sb, Ba, Pb and Bi), than those observed using the GD.1.
Keywords: Pulsed radiofrequency glow discharge; Time-of-flight mass spectrometry; Ion source; Glass analysis
Development of a liquid–chromatography tandem mass spectrometry and ultra-high-performance liquid chromatography high-resolution mass spectrometry method for the quantitative determination of zearalenone and its major metabolites in chicken and pig plasma by S. De Baere; A. Osselaere; M. Devreese; L. Vanhaecke; P. De Backer; S. Croubels (pp. 37-48).
Display Omitted► Qualitative+quantitative analyses of zearalenone with LC–MS/MS and (U)HPLC–HR–MS. ► Development of a generic, rapid and cheap sample preparation procedure. ► Chromatograhy: baseline separation of metabolites with same precursor ion, run-time: 10min. ► Method validation: linearity, accuracy, precision, LOQ, LOD, specificity, recovery and matrix effects. ► Investigation of toxicokinetics of zearalenone in chickens.A sensitive and specific method for the quantitative determination of zearalenone (ZEN) and its major metabolites (α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), α-zearalanol (α-ZAL), β-zearalanol (β-ZAL) and zearalanone (ZAN)) in animal plasma using liquid chromatography combined with heated electrospray ionization (h-ESI) tandem mass spectrometry (LC–MS/MS) and high-resolution Orbitrap® mass spectrometry ((U)HPLC–HR–MS) is presented. The sample preparation was straightforward, and consisted of a deproteinization step using acetonitrile. Chromatography was performed on a Hypersil Gold column (50mm×2.1mm i.d., dp: 1.9μm, run-time: 10min) using 0.01% acetic acid in water (A) and acetonitrile (B) as mobile phases.Both mass spectrometers were operated in the negative h-ESI mode.The method was in-house validated for all analytes: matrix-matched calibration graphs were prepared and good linearity ( r≥0.99) was achieved over the concentration range tested (0.2–200ngmL−1). Limits of quantification (LOQ) in plasma were between 0.2 and 5ngmL−1 for all compounds. Limits of detection in plasma ranged from 0.004 to 0.070ngmL−1. The results for the within-day and between-day precision, expressed as relative standard deviation (RSD), fell within the maximal RSD values (within-day precision: RSDmax=2(1–0.5logConc) x 2/3; between-day precision: RSDmax=2(1–0.5logConc)). The accuracy fell within −50% to +20% (concentrations <1ngmL−1), −30% to +10% (concentrations between 1 and 10ngmL−1) or −20% to +10% (concentrations >10ngmL−1) of the theoretical concentration.The method has been successfully used for the quantitative determination of ZEN in plasma samples from broiler chickens and pigs. α-ZEL and β-ZEL were the only metabolites that could be detected, but the concentrations were around the LOQ levels. The intact ZEN-glucuronide conjugate could be detected using the (U)HPLC–HR–MS instrument. A good correlation ( r2=0.9979) was observed between the results for ZEN obtained with the LC–MS/MS and (U)HPLC–HR–MS instruments. The results prove the usefulness of the developed method for application in the field of toxicokinetic analysis and for exposure assessment of mycotoxins.
Keywords: Abbreviations; ADME; absorption distribution metabolization and excretion; BW; body weight; EFSA; European Food Safety Authority; EIC; extracted ion chromatogram; EU; European Union; FDA; Food and Drug Administration; FL; fluorescence detection; FWHM; full width at half maximum; g; goodness-of-fit coefficient; h-ESI; heated electrospray ionization; HPLC; high-performance liquid chromatography; HR; high-resolution; IAC; immunoaffinity column; IS; internal standard; IV; intravenous; LC–MS/MS; liquid–chromatography tandem mass spectrometry; LOD; limit of detection; LOQ; limit of quantification; MF; mobile phase; MS; mass spectrometry; MS/MS; tandem mass spectrometric detection; m; /; z; mass to charge ratio; N; 2; nitrogen; OR; oral; QC; quality control; r; correlation coefficient; R; E; extraction recovery; RSD; relative standard deviation; RRT; relative retention time; S/N; signal-to-noise ratio; SRM; Selected reaction monitoring mode; SSE; signal suppression/enhancement; TIC; total ion chromatogram; Tr; retention time; (U)HPLC–HR–MS; ultra-high-performance liquid chromatography high-resolution mass spectrometry; UV; ultraviolet detection; ZAN; zearalanone; ZEN; zearalenone; α-ZEL; α-Zearalenol; β-ZEL; β-Zearalenol; α-ZAL; α-Zearalanol; β-ZAL; β-ZearalanolZearalenone; Liquid chromatography tandem mass spectrometry; Ultra-high-performance high-resolution mass spectrometry; Plasma; Toxicokinetics
Aromatic amines from polyurethane adhesives in food packaging: The challenge of identification and pattern recognition using Quadrupole-Time of Flight-Mass SpectrometryE by Davinson Pezo; Mauro Fedeli; Osvaldo Bosetti; Cristina Nerín (pp. 49-59).
Display Omitted► 18 primary aromatic amines from adhesives in multilayer plastics are analysed by UPLC–LC–TQ. ► Non intentionally added substances are identified in the multilayer materials by UPLC–Q-TOF–MS. ► Quantitative values of PAAs are compared to those obtained by colorimetric method using NEDA. ► Overestimation of NEDA procedure is demonstrated. ► Pattern recognition of the impurities and NIAS from adhesives in the multilayers are achieved.Toxic primary aromatic amines (PAAs) are reaction products from residual isocyanates in polyurethane adhesives. The maximum migration level of the total sum of PAAs is 10ngg−1 of food. This paper reports on a method for quantification of 18 PAAs by UHPLC–MS/MS that was optimised and applied to a series of industrial laminates prepared from polyurethane adhesives. Non-intentionally added substances (NIAS), impurities and other migrants were identified by Q-TOF/MSE. A comparison of the quantitative values obtained by the colorimetric method using NEDA and by UHPLC–MS/MS confirmed that the first method can overestimate the quantification of PAAs. This could be attributed to the impurities and other NIAS present in the plastic laminate. Values of R2 in the analytical characteristics of UHPLC–MS/MS were obtained, the best value being 0.9964 and the most unfavourable 0.7626. The detection limit (LOD) and the quantification limit (LOQ) were 2pgg−1 and 7pgg−1, respectively. The stability of the PAAs over time in the acidic simulant in contact with the plastic laminate is also reported.
Keywords: Multilayer food packaging; Migration; Primary aromatic amines; Non-intentionally added substances; Polyurethane adhesives; Solid phase extraction
Metabolic studies of the Amaryllidaceous alkaloids galantamine and lycorine based on electrochemical simulation in addition to in vivo and in vitro models by Sandra Jahn; Bettina Seiwert; Sascha Kretzing; Getu Abraham; Ralf Regenthal; Uwe Karst (pp. 60-72).
Display Omitted► Biotransformation pathways of the two Amaryllidaceae alkaloids galantamine and lycorine were investigated. ► Three different methods were used and compared including an in vivo, in vitro and electrochemical (EC) approach. ► It was possible to predict most of the metabolites observed during conventional plasma and microsomal studies with EC. ► Dealkylation, dehydrogenation and oxygenation were found to be the main metabolic routes of both alkaloids.Alkaloids from the plant family of Amaryllidaceae, such as galantamine (GAL) and lycorine (LYC), are known to exhibit numerous promising biological and pharmacological activities like antibacterial, antiviral or anti-inflammatory effects. Nonetheless, studies on the biotransformation pathway are rare for this substance class, unless approval for use as medication exists. While GAL has become a prescription drug used to alleviate and delay the symptoms of Alzheimer's disease, LYC exhibits potential antitumor properties. However, it has also been linked to toxic effects resulting in nausea and emesis. Whereas there are few publications available describing the metabolic pathway of GAL in animals and humans, the metabolism of LYC is unknown. Therefore, this study is concerned with the investigation of the oxidative metabolism of GAL and LYC, which was achieved by means of three different approaches: electrochemical (EC) simulation coupled on-line to liquid chromatography (LC) with electrospray mass spectrometric (ESI-MS) detection was applied in addition to in vivo experiments in beagle dog analyzing plasma (BP) and in vitro incubations with rat liver microsomes (RLM). This way, it should be investigated if electrochemistry can be used to predict the oxidative metabolism of alkaloids. For GAL, the EC model was capable of predicting most metabolites observed during microsomal and plasma studies, including N-demethylated, dehydrogenated and oxygenated products or a combination of these. LYC was found to be metabolized far less than GAL in the animal-based approaches, but several EC oxidation products were generated. Some principal metabolic routes could successfully be correlated for this alkaloid as well, comprising dehydrogenation, dehydration to ungeremine and oxygenation reactions.
Keywords: Amaryllidaceae; alkaloids; Galantamine; Metabolism; Electrochemistry; Liquid chromatography; Mass spectrometry
An electrochemiluminescence strategy based on aptamers and nanoparticles for the detection of cancer cells by Caifeng Ding; Qian Zheng; Nannan Wang; Qifeng Yue (pp. 73-78).
An electrochemiluminescence (ECL) strategy based on aptamers and ECL nanoprobes was developed for the rapid collection and detection of Ramos cells.Display Omitted► Gold nanoparticles (AuNPs) modified with numerous of ECL signal molecules were used for the amplification of ECL detection. ► Magnetic beads (MBs) were used for the separation tool. ► Under the optimum conditions, a limit of detection as low as 50 Ramos cells per mL could be achieved.A PCR (polymerase chain reaction)-free electrochemiluminescence (ECL) strategy based on aptamers and ECL nanoprobes was developed for rapid collection and detection of Ramos cells. The ECL nanoprobes consisted of gold nanoparticles (AuNPs), linker DNA and tris-(2,2′-bipyridyl) ruthenium (TBR)-labeled signal DNA. The linker DNA and signal DNA were modified on the surface of the AuNPs through AuS bonds. The linker DNA can hybridize partly with the aptamers loaded on the magnetic beads to construct the magnetic biocomplex. In the presence of the cancer cells, the aptamers conjugated with the cancer cells with higher affinity. The ECL nanoprobe released from the biocomplex and subsequently hybridized with the capture DNA modified on the Au electrode. The ECL intensity of the TBR loaded on the nanoprobes directly reflected the amount of the cancer cells. With the use of the developed ECL probe, a limit of detection as low as 50 Ramos cells per mL could be achieved. The proposed methods based on ECL should have wide applications in the diagnosis of cancers due to their high sensitivity, simplicity and low cost.
Keywords: Gold nanoparticles (AuNPs); Electrochemiluminescence (ECL); Aptamer; Magnetic beads; Cancer cells