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1.
A method based on gas chromatography–tandem mass spectrometry after derivatization with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide was developed for the analysis of monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in hair. The method focused on 52 target compounds corresponding to two- to six-ring monohydroxylated metabolites of polycyclic aromatic hydrocarbons (PAHs). The limits of quantification ranged from 0.2 to 50 pg mg?1. The method was then applied to the analysis of hair samples collected from rats exposed to 12 PAHs at 0.01, 0.1, and 1 mg kg?1, by intraperitoneal injection, for 28 days. The results of this study confirm that these metabolites can be incorporated in hair after intraperitoneal administration of the corresponding parent compound. Only 20 of the 52 metabolites were actually detected in hair samples and corresponded to nine parent PAHs. The mean concentrations of OH-PAHs in rat hair samples exposed to PAHs at 1 mg kg?1 ranged from 0.6?±?0.2 pg mg?1 for 8-hydroxybenzo[b]fluoranthene to 6.7?±?1.0 pg mg?1 for 1-hydroxypyrene. The results also demonstrated that hair pigmentation has no influence on the concentration of most OH-PAHs. This animal experiment confirmed the incorporation of PAH metabolites in hair and demonstrated that the method was sufficiently sensitive to detect low levels of exposure to PAHs. These results confirmed the usefulness of hair analysis in the biomonitoring of human exposure to PAHs.
Figure
Analysis of 52 monohydroxylated polyccyclic aromatic hydrocarbons in a supplemented hair sample by GC-EI-MS/MS  相似文献   

2.
We report on a protocol for a simultaneous competitive immunoassay for tetracycline (TC) and chloramphenicol (CAP) on the same sensing interface. Conjugates of TC and of CAP with bovine serum albumin were first co-immobilized on a glassy carbon electrode modified with gold nanoparticles. In parallel, monoclonal anti-TC and anti-CAP antibodies were conjugated onto CdS and PbS nanoclusters, respectively. In a typical assay, the immobilized haptens and the added target analytes competed for binding to the corresponding antibodies on the nanoclusters. Subsequently, Cd(II) and Pb(II) ions are released from the surface of the corresponding nanoclusters by treatment with acid and then were detected by square wave anodic stripping voltammetry. The currents at the peak potentials for Cd(II) and Pb(II) were used as the sensor signal for TC and CAP, respectively. This multiplex immunoassay enables the simultaneous determination of TC and CAP in a single run with dynamic ranges from 0.01 to 50 ng mL?1 for both analytes. The detection limits for TC and for CAP are 7.5 pg mL?1 and 5.4 pg mL?1, respectively. No obvious nonspecific adsorption and cross-reactivity was observed in a series of analyses. Intra-assay and inter-assay coefficients of variation were less than 10 %. The method was evaluated by analyzing TC and CAP in spiked samples of milk and honey. The recoveries range from 88 % to 107 % for TC, and from 91 % to 119 % for CAP.
Figure
We developed a new multiplexed electrochemical immunoassay for simultaneous determination of tetracycline and chloramphenicol, using metal sulfide nanoclusters as recognition elements.  相似文献   

3.
We have developed a method for the determination of trace levels of the rare earth elements La, Eu, and Yb in biological and environmental samples. It is based on solidified floating organic drop microextraction using 1-(2-pyridylazo)-2-naphthol (PAN) as a chelator, followed by electrothermal vaporization (ETV) and quantification by inductively coupled plasma mass spectrometry. PAN also acts as a modifier in ETV. The effects of pH, amount of PAN, extraction time, stirring rate, volume of sample solution, and temperature program were examined. Under optimized conditions, the detection limits are 2.1, 0.65 and 0.91 pg mL?1 for the elements La, Eu and Yb, respectively. The relative standard deviations are <6.0 % (c?=?0.1 ng mL?1, n?=?9). When applied to the analysis of (spiked) natural water samples, the recoveries range from 92 to 105 %. The accuracy was validated with certified reference materials (combined sample of branch and leaf of shrub: GBW 07603 and human hair: GBW 07601), and the results were in good agreement with the certified values.
Figure
?Solidified floating organic drop microextraction was combined with ETV for ICP-MS. ?PAN acted as both a chelating agent and a chemical modifier. ?The method was used for analysis of rare earth elements in real samples. ?The method has the merits of low detection limit, good precision and accuracy.  相似文献   

4.
A functionalized gold-nanoparticle bio-barcode assay, based on real-time immuno-PCR (IPCR), was designed for the determination of 3,4,3',4'-tetrachlorobiphenyl (PCB77). 15 nm gold nanoparticles were synthesized, and modified with thiol-capped DNA and goat anti-rabbit IgG. The nanoparticle probes were used to replace antibody–DNA conjugate in the IPCR, and were fixed on the PCR tube wall via the immune reaction. Real-time PCR was performed to quantify the DNA signal directly. Under optimized conditions, the new method was used to detect PCB77 with a linearity range from 5 pg L?1 to 10 ng L?1, and the limit of detection (LOD) was 1.72 pg L?1. Real samples of Larimichthys polyactis, collected from the East China Sea, were analyzed. Recovery was from 82 % to 112 %, and the coefficient of variation (CV) was acceptable. The results were compared with GC–ECD, revealing that the method would be acceptable for providing rapid, semi-quantitative, and reliable test results for making environmental decisions.
FIGURE
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5.
We describe a simple, environmentally friendly and selective technique for the determination of ochratoxin A (OTA) in urine. It involves (a) the use of a molecularly imprinted polymer as a sorbent in micro-solid-phase extraction in which the sorbent is contained in a propylene membrane envelope, and (b) separation and detection by capillary electrophoresis (CE). Under optimized conditions, response is linear in the range between 50 and 300 ng mL?1 (with a correlation coefficient of 0.9989), relative standard deviations range from 4 to 8 %, the detection limit for OTA in urine is 11.2 ng mL?1 (with a quantification limits of 32.5 ng mL?1) which is lower than those of previously reported methods for solid-phase extraction combined with CE. The recoveries of OTA from urine spiked at levels of 50, 150 and 300 ng mL?1 ranged from 93 to 97 %.
Figure
?  相似文献   

6.
In this research, a mixed immunoassay design for multiple chemical residues detection based on combined reverse competitive enzyme-linked immunosorbent assay (ELISA) procedure was developed. This method integrated two reverse ELISA reactions in one assay by labeling horseradish peroxidase to deoxynivalenol (DON) and orbifloxacin. Within this method, IC50 of the two mAbs for each analyte we produced ranged from 23?~?68 ng?mL?1 for DONs and 4.1?~?49 ng?mL?1 for quinolones (QNs). The limit of detection measured by IC10 was achieved at 0.45–1.3 ng?mL?1 for DONs and 0.59–6.9 ng?mL?1 for QNs, which was lower than the maximum residue levels. Recoveries in negative samples spiked at concentrations of 100, 200, and 500 ng?mL?1 ranged from 91.3 to 102.2 % for DONs and 88.7–98.05 % for QNs with relative standard deviation less than 9.88 and 12.67 %. The results demonstrated that this developed immunoassay was suitable for screening of low molecular weight contaminants.
Figure
Combined reverse ELISA procedure for multi-chemical residues analysis  相似文献   

7.
Catecholamines play essential roles in several physiological processes in vertebrates as well as in invertebrates. While several studies have shown the presence of these substances in surface water invertebrates, their occurrence in groundwater fauna is unproven. In the present study, the presence of different catecholamines (i.e., noradrenaline, adrenaline, and dopamine) in individual specimens of groundwater amphipods of the genus Niphargus (mostly Niphargus inopinatus) was investigated via two independent analytical methods: HPLC/EcD and UPLC/TOF-MS. Mean values for catecholamine levels were 533 pg mg?1 fresh weight for noradrenaline, 314 pg mg?1 for adrenaline, and 16.4 ng mg?1 for dopamine. The optimized protocol allowed the detection of CAs in single organisms of less than 1 mg fresh weight. Catecholamine concentration patterns in groundwater invertebrates are briefly discussed here with respect to their evolutionary adaptation to an environmentally stable, energy-poor habitat.
Figure
Niphargus inopinatus SCHELLENBERG (photo: Günter Teichmann,Helmholtz Center Munich)  相似文献   

8.
We report on a multiplex bead-based competitive immunoassay using suspension array technology for the simultaneous detection of the pesticides triazophos, carbofuran and chlorpyrifos. Three hapten-protein conjugates were covalently bound to carboxylated fluorescent microspheres to serve as probes. The amount of conjugates and antibodies were optimized. The new multi-analyte assay has dynamic ranges of 0.02–50 ng?mL?1, 0.5–500 ng?mL?1 and 1.0–1000 ng?mL?1 for triazophos, carbofuran and chlorpyrifos, respectively, and the detection limits are 0.024, 0.93 and 1.68 ng?mL?1. This new multiplex assay is superior to the traditional ELISA in possessing a wider detection range, better reproducibility and the feature of multi-target detection. Cross-reactivity studies indicated that the bead-array method is highly selective for the three target pesticides, and that individual analyses have no significant influence between each other, also without cross-reactions from other structurally related pesticides. The method was applied to analyze vegetables spiked with the three pesticides, and the recoveries were in ranges of 78.5–112.1 %, 72.2–120.2 % and 70.2–112.8 %, respectively, with mean coefficients of variation of <15 %.
Figure
Schematic illustration of the multiplex bead-based competitive immunoassay  相似文献   

9.
We present two kinds of electrochemical immunoassays for the tumor necrosis factor α (TNF-α) which is a protein biomarker. The antibody against TNF-α was immobilized on a graphite screen-printed electrode modified with poly-anthranilic acid (ASPE). The first is based on impedimetry (and thus label-free) and the target antigen (TNF-α) is captured by the surface of the modified electrode via an immunoreaction upon which impedance is changed. This sensing platform has a detection limit of 5.0 pg mL?1. In the second approach, the monoclonal antibodies on the modified electrode also bind to the target antigen (TNF-α), but detection is based on a sandwich immunoreaction. This is performed by first adding secondary anti-TNF-α antibodies labeled with horseradish peroxidase, and then detecting the response of the sandwich system by adding hydrogen peroxide and acetaminophen as a probe system for HRP activity. This immunosensor also has a very low detection limit (3.2 pg mL?1). The experimental conditions of both assays were studied and optimized via electrochemical impedance spectroscopy and differential pulse voltammetry. The method was then applied to the determination of TNF-α in serum samples where it displayed high sensitivity, selectivity and reproducibility.
Figure
A novel electrochemical immunosensor capable of sensitive and selective detection of tumor necrosis factor α is developed. It is based on the poly-anthranilic acid modified graphite screen-printed electrodes. Validation was made by analyzing human serum.  相似文献   

10.
A total sample-preparation and analysis time of 50 min is required for the high-throughput method of hair analysis proposed in this paper. The method is applicable to analysis of drugs commonly used in Asia, and their metabolites—methamphetamine (MA), amphetamine (AMP), methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA), ketamine (K), norketamine (NK), dehydronorketamine (DHNK), 6-acetylmorphine (6-AM), morphine (MOR), and codeine (COD). Cut and weighed hair (10 mg) was incubated for 3 min with methanol–trifluoroacetic acid (TFA) during microwave-assisted extraction (MAE) at 700 W. The incubation solution was evaporated, the residue was reconstituted in deionized water–methanol, 99:1 (v/v), and 20 μL was injected on to a core-shell column (50?×?4.6 mm, 2.6 μm particle size) for liquid chromatographic–tandem mass spectrometric (LC–MS–MS) analysis. Gradient elution separation was performed in 8 min at a flow rate of 1 mL min?1. No signal interfering with any of the analytes was found in fourteen blank hair samples from different sources. The limits of detection and quantification were 0.5 pg mg?1 and 2.0 pg mg?1, respectively, for MA, AMP, MDMA, MDA, K, NK, and DHNK, and 2.0 pg mg?1 and 5.0 pg mg?1, respectively, for 6-AM, MOR and COD. The linear range was between the LOQ and 1000 pg mg?1, and the correlation coefficients were all greater than 0.999. Investigation of matrix effects revealed that all the analytes were suppressed by less than 20 % and the standard deviation (SD) was always less than 7 %. Recovery was always greater than 90 % and the SD for each compound was less than 6 %. Precision and accuracy for each analyte were within 15 %. Eight authentic hair specimens from known drug abusers were successfully analyzed. Compared with traditional overnight incubation methods, the rapid 3-min extraction time achieved similar or greater extraction yields. Sample preparation by MAE was a reliable procedure for extraction of the analytes from hair but substantially simpler and faster than other methods.
Figure
A high-throughput hair analysis method based on microwave-assisted extraction and liquid chromatography - tandem mass spectrometry  相似文献   

11.
We report on the use of hollow fiber liquid-liquid-liquid microextraction (HF-LLLME) followed by corona discharge ion mobility spectrometry for the determination of dextromethorphan and pseudoephedrine in urine and plasma samples. The effects of pH of the donor phase, stirring rate, ionic strength and extraction time on HF-LLLME were optimized. Under the optimized conditions, the linear range of the calibration curves for dextromethorphan in plasma and urine, respectively, are from 1.5 to 150 and from 1 to 100 ng mL?1. The ranges for pseudoephedrine, in turn, are from 30 to 300 and from 20 to 200 ng mL?1. Correlation coefficients are better than 0.9903. The limits of detection are 0.6 and 0.3 ng mL?1 for dextromethorphan, and 8.6 and 4.2 ng mL?1 for pseudoephedrine in plasma and urine samples, respectively. The relative standard deviations range from 6 to 8%.
Figure
Hollow fiber liquid–liquid–liquid microextraction (HF-LLLME) followed by corona discharge ion mobility spectrometry (CD-IMS) was used for the determination of dextromethorphan and pseudoephedrine in urine and plasma samples.  相似文献   

12.
We report on an ultrasensitive fluorescence immunoassay for human chorionic gonadotrophin antigen (hCG). It is based on the use of silica nanoparticles coated with a copolymer (prepared from a fluorene, a phenylenediamine, and divinylbenzene; PF@SiO2) that acts as a fluorescent label for the secondary monoclonal antibody to β-hCG antigen. In parallel, Fe3O4 nanoparticles were coated with polyaniline, and these magnetic particles (Fe3O4@PANI) served as a solid support for the primary monoclonal antibody to β-hCG antigen. The PF@SiO2 exhibited strong fluorescence and good dispersibility in water. A fluorescence sandwich immunoassay was developed that enables hCG concentrations to be determined in the 0.01–100 ng·mL?1 concentration range, with a detection limit of 3 pg·mL?1.
Figure
Fluorescence detection of prepared immune reagent nano-composites using the fluorescence cell  相似文献   

13.
We describe a new method for differential-pulse anodic stripping voltammetric determination of thallium(I) using a carbon paste electrode modified with dicyclohexyl-18-crown-6. The effect of supporting electrolyte (type and pH), accumulation and reduction potential, and of time and amount of modifier were investigated by differential pulse anodic stripping voltammetry. A method was then worked out for the determination of thallium at low levels. Under optimized conditions, the response to Tl(I) is linear in the range from 3.0 to 250 ng mL?1. The detection limit is 0.86 ng mL?1. The sensor displays good repeatability (with a relative standard deviation of ±2.70 % for n?=?7) and was applied to the determination of Tl(I) in water, hair samples, and certified reference materials.
Figure
Crown ethers allow only some ions to entry and complex formation that their sizes equal to ether cavity.  相似文献   

14.
We report on label-free immunosensors for the highly sensitive detection of avian influenza virus. The method makes use of the microcantilevers of an atomic force microscope onto which monoclonal antibodies against avian influenza virus were covalently immobilized. The factors influencing the performance of the resulting immunosensors were optimized by measuring the deflections of the cantilever via optical reflection, and this resulted in low detection limits and a wide analytical range. The differential deflection signals revealed specific antigen binding and their intensity is proportional to the logarithm of the concentrations of the virus in solution. Under optimal conditions, the immunosensors exhibit a linear response in the 7.6 ng mL?1 to 76 μg mL?1 concentration range of avian influenza virus, and the detection limit is 1.9 ng mL?1.
Figure
Label-free immunosensors based on microcantilevers of an atomic force microscope was fabricated by covalently immobilizing monoclonal antibodies to avian influenza virus onto the microcantilever. The performance and factors influencing the performance of the resulting immunosensors were investigated in detail by measuring the cantilever deflections using the optical reflection technique.  相似文献   

15.
We describe a simple method for the synthesis of highly magnetic and fluorescent bifunctional chitosan nanoparticles (MF-CSNPs). Water-soluble and magnetic Fe3O4-chitosan nanoparticles and CdSe quantum dots capped with thioglycolic acid were incorporated into a chitosan matrix via electrostatic interaction. The optical, magnetic, crystallographic and morphological properties of the new nanoparticles were studied by UV-visible, fluorescence, X-ray diffraction and transmission electron microscopy. In addition, MF-CSNPs are found to be a useful probe for the determination of copper ion which acts as a quencher of fluorescence. The relative fluorescence intensity of MF-CSNPs is linearly related to the concentration of copper ion in the 0.125 to 25 ng·mL-1 concentration range. The MF-CSNPs also are found to adsorb copper ion which therefore can be separated and enriched by manipulating them with an external magnetic field. Before enrichment, the limit of detection (LOD) for copper ion is 120 pg·mL-1, but after enrichment, the LOD is 46 pg·mL-1.
Figure
High magnetic and fluorescent bifunctional chitosan nanoparticles (MF-CSNPs) have been successfully synthesized via electrostatic interaction. MF-CSNPs are shown to represent a quenchable fluorescent probe for the detection of copper ion in water solution.  相似文献   

16.
We have developed a simple and efficient method for dispersive liquid-liquid microextraction of 4-nitrophenol, 2-naphthol and bisphenol A in real water samples. It is making use of solidified floating organic droplets of 1-dodecanol which has low density and a proper melting point. The type and volume of extraction solvent and dispersive solvent, the effect of salts, pH value and extraction time were optimized and resulted in enrichment factors of 84 for 4-nitrophenol, 123 for 2-naphthol, and 97 for bisphenol A. The limits of detection by HPLC are 1.50, 0.10 and 1.02 ng · mL?1, respectively. Excellent linearity is observed in the concentration range from 10 to 800 ng · mL?1, with coefficients of correlation ranging from 0.9988 to 0.9999. The relative standard deviations (for n?=?5) are from 3.2 to 5.3 %, and relative recoveries for the three phenols in tap, river and spring water range from 85.0 to 105.0 %, 98.3 to 110.0 %, and 98.6 to 109.0 %, respectively.
Figure
Chromatograms of river water blank (b) and spiked river water (a, 500 ng ? mL?1) analyzed with DLLME-SFO-HPLC. Peak identification: (1) p-nitrophenol; (2) 2-naphthol; (3) bisphenol A. Liquid-liquid microextraction method based on solidification of floating organic droplet (DLLME-SFO) has a high enrichment factor (84, 123and 97), acceptable relative recovery (85.0 %–110.0 %), good repeatability (5.27 %, 3.54 % and 3.16 %) and a wide linear range (10–800 ng · mL?1) for the determination of p-nitrophenol, 2-naphthol and bisphenol A.  相似文献   

17.
A novel type of porous metal-organic framework (MOF) was obtained from thiol-modified silica nanoparticles and the copper(II) complex of trimesic acid. It is shown that this nanocomposite is well suitable for the preconcentration of Hg(II) ions. The nanocomposite was characterized by Fourier transfer infrared spectroscopy, X-ray powder diffraction, energy-dispersive X-ray diffraction and scanning electron microscopy. The effects of pH value, sorption time, elution time, the volume and concentration of eluent were investigated. Equilibrium isotherms were studied, and four models were applied to analyze the equilibrium adsorption data. The results revealed that the adsorption process obeyed the Langmuir model. The maximum monolayer capacity and the Langmuir constant are 210 mg g?1 and 0.273 L mg?1, respectively. The new MOF-based nanocomposite is shown to be an efficient and selective sorbent for Hg(II). Under the optimal conditions, the limit of detection is 20 pg mL?1 of Hg(II), and the relative standard deviation is <7.2 % (for n?=?3). The sorbent was successfully applied to the rapid extraction of Hg(II) ions from fish, sediment, and water samples.
Figure
Schematic illustration of Hg(II) sorption onto SH@SiO2/MOF nanocomposite.  相似文献   

18.
The anti-schizophrenic drug risperidone (RSP) exerts an inhibitory effect on the chemiluminescence (CL) of the luminol-lysozyme system. This finding forms the basis for a sensitive flow injection method for its determination at picogram levels. RSP binds to Trp62 in the lysozyme, and this leads to a conformational change upon which the CL of the system is quenched. The decrease in CL is proportional to the logarithm of the concentration of RSP, and the calibration graph is linear in the range from 0.1 pg?mL?1 to 1.0 ng?mL?1, with relative standard deviations of <5.0%, and a detection limit of 0.05 pg?mL?1 (3σ). At a flow rate of 2.0 mL?min?1, the whole process including sampling and washing is completed within 20 s. The method was successfully applied to monitoring RSP in human urine after incorporation of 2 mg of RSP, with a total excretion of 16.6% within 8.5 h.
Figure
The reaction of lysozyme with risperidone using luminol as luminescence reagent by the luminol-lysozyme FI-CL system and its application.  相似文献   

19.
We have developed a specific method for the visual detection of Staphylococcus aureus based on aptamer recognition coupled to tyramine signal amplification technology. A biotinylated aptamer specific for S. aureus was immobilized on the surface of the wells of a microplate via biotin-avidin binding. Then, the target bacteria (S. aureus), the biotinylated-aptamer-streptavidin-HRP conjugates, biotinylated tyramine, hydrogen peroxide and streptavidin-HRP were successively placed in the wells of the microplate. After adding TMB reagent and stop solution, the intensity of the yellow reaction product can be visually inspected or measured with a plate reader. Under optimized conditions, there is a linear relationship between absorbance at 450 nm and the concentration of S. aureus in the 10 to 107 cfu mL?1 concentration range (with an R2 of 0.9976). The limit of detection is 8 cfu mL?1.
Figure
A visual detection method for Staphylococcus aureus was based on aptamer recognition coupled to tyramine signal amplification. The linear range was from 10 to 107 cfu mL-1 and the limit of detection was 8 cfu mL-1.  相似文献   

20.
Graphene-based magnetic nanoparticles (G-Fe3O4) were prepared and used as an effective adsorbent for the solid-phase extraction of trace quantities of cadmium from water and vegetable samples. The method avoids some of the time-consuming steps associated with traditional solid phase extraction. The excellent sorption property of the G-Fe3O4 system is attributed to π - π stacking interaction and hydrophobic interactions between graphene and the Cd-PAN complex. The effects of pH, the amount of G–Fe3O4, extraction time, type and volume of eluent, desorption time and interfering ions on the extraction efficiency were optimized. The preconcentration factor is 200. Cd(II) was then quantified by flame atomic absorption spectrometry with a detection limit of 0.32 ng mL?1. The relative standard deviation (at 50 ng mL?1; for n?=?10) is 2.45 %. The method has a linear analytical range from 1.1 to 150 ng mL?1, and the recoveries in case of real samples are in the range between 93.1 % and 102.3 %.
Figure
General procedure for magnetic preconcentration of cadmium ions from aqueous solution using graphene-based magnetic nanoparticles  相似文献   

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