6007results about How to "Low detection limit" patented technology

A gas sensing device (nanosensor) includes a substrate with at least a pair of conductive electrodes spaced apart by a gap, and an electrochemically functionalized semiconductive nanomaterial bridging the gap between the electrodes to form a nanostructure network. The nanomaterial may be single-walled carbon nanotubes (SWNTs) functionalized by the deposition of nanoparticles selected from the group consisting of an elemental metal (e.g., gold or palladium), a doped polymer (e.g., camphor-sulfonic acid doped polyaniline), and a metal oxide (e.g. tin oxide). Depending on the nanoparticles employed in the functionalization, the nanosensor may be used to detect a selected gas, such as hydrogen, mercury vapor, hydrogen sulfide, nitrogen dioxide, methane, water vapor, and/or ammonia, in a gaseous environment.

The invention provides methods for the measurement of carbon dioxide leakage from sequestration reservoirs. Tracer moieties are injected along with carbon dioxide into geological formations. Leakage is monitored by gas chromatographic analyses of absorbents. The invention also provides a process for the early leak detection of possible carbon dioxide leakage from sequestration reservoirs by measuring methane (CH₄), ethane (C₂H₆), propane (C₃H₈), and/or radon (Rn) leakage rates from the reservoirs. The invention further provides a method for branding sequestered carbon dioxide using perfluorcarbon tracers (PFTs) to show ownership.

Methods and apparatus for performing a binding assay for an analyte of interest present in a sample are described. The methods include the steps of: forming a composition containing the sample, an assay-performance-substance which contains a component linked to a label compound capable of chemiluminescing when triggered, and a plurality of particles capable of specifically binding with the analyte and/or the assay-performance-substance; incubating the composition to form a complex which includes a particle and the labeled component; collecting the complex in a collection zone; introducing into the collection zone a trigger capable of triggering the label such that the label luminesces; and measuring the emitted luminescence to measure the presence of the analyte of interest in the sample.

Components resolved in time by a separator accumulate in a sample cell and are analyzed by electromagnetic radiation-based spectroscopic techniques. The sample cell can be configured for multiple path absorption and can be heated. The separator can be a gas chromatograph or another suitable device, for example a distillation-based separator. The method and system described herein can include other mechanical elements, controls, procedures for handling background and sample data, protocols for species identification and/or quantification, automation, computer interfaces, algorithms, software or other features.

The invention provides a flexible pressure sensor and a preparation method therefor. The flexible pressure sensor comprises an upper flexible substrate and a lower flexible substrate which are arranged oppositely in parallel, an upper sensitive layer which is attached to the lower surface of the upper flexible substrate in a conformal manner and a lower sensitive layer which is attached to the upper surface of the lower flexible substrate in a conformal manner, wherein the upper sensitive layer is provided with an upper electrode while the lower sensitive layer is provided with a lower electrode; the upper electrode and the lower electrode are not crossed mutually; a contact region is formed between the upper sensitive layer and the lower sensitive layer; multiple multi-stage lug bosses are arranged on the lower surface of the upper flexible substrate and the upper surface of the lower flexible substrate respectively; and the multi-stage lug bosses are 50-100[mu]m in average lengths and 1-10[mu]m in average heights. The flexible pressure sensor provided by the invention has the flexible substrates which are obtained by impression and have special convex microstructures, so that the surface roughness is improved, and the sensitivity of the sensor is greatly improved.

The invention provides a method for detecting fatty acid content in animal sample by gas chromatography-mass spectrometry (GC-MS), to solve the problems of complicated sample treatment steps and high cost in conventional methods in practical production and scientific research. The method comprises the steps of treating animal tissue samples; extracting, saponifying and methylating fatty acids; determining GC-MS conditions for fatty acid detection; analyzing data and identifying sample. The method has the advantages of simple operation, low detection limit, good reproducibility, and visual andreliable experiment data; is especially suitable for trace sample detection, can compare fatty acid compositions and contents among different samples, has wider application, and provides a new thought and method for rapid detection of fatty acid composition and content in animal sample for scientific research, clinical application, and food quality and safety monitoring.

The invention discloses a method for detecting aflatoxin through an immunosensor. The aflatoxin (AFT) is a fungal toxin which has the high carcinogenicity, teratogenicity and toxicity, and accurate and rapid analysis on the aflatoxin is one of most effective means for reducing and avoiding harm of the aflatoxin. A prepared gold-polyaniline-graphene (Au-PANI-GN) composite nanomaterial is represented by adopting an ultraviolet spectrum and a transmission electron microscope and used for constructing the electrochemical immunosensor, the electrochemical immunosensor is represented by adopting a cyclic voltammetry method, an electrochemical AC impedance method and a square wave voltammetry method, and the prepared electrochemical immunosensor detects the aflatorxin B1. Experiment results show that the constructed electrochemical immunosensor has the good electrochemical activity on detection of the aflatoxin, and the concentrations of the aflatoxin and peak currents have the good linear relation, wherein the linear equation of the relation is y=-0.177x+4.28.

The invention relates to a making method and an application of a CdS sensitized TiO2 environmental estrogen photoelectrochemical sensor. The method uses TiO2 as an antigen capture substrate material, a CdS photoelectric active material is in situ generated on the surface of a Cd2<+> functional TiP nanomaterial maker modified electrode through a direct Na2S dropping technology, and CdS is irritated by an LED lamp of visible light wavelength to be converted to a photoelectric current signal. The substrate material TiO2 can be well matched with CdS energy band, so the photocurrent conversion signal of CdS is further improved, thereby the competitive photoelectrochemical immunosensor for ultra sensitive detection of estradiol, estriol, diethylstilbestrol, bisphenol A, nonylphenol, oestrone and other environmental pollutants is made.

The invention relates to an in-situ preparation method of a copper nano-cluster/carbon dot (Cu NCs/CDs) double-fluorescence-emission colorimetric probe based on AIEE, and application thereof in detecting trace water in an organic solvent, which belong to the technical field of colorimetric sensing. The method comprises three steps of synthesizing blue-fluorescence carbon dots (CDs), carrying out surface modification on the CDs, and preparing the double-fluorescence-emission Cu NCs/CDs probe. The double-fluorescence-emission probe Cu NCs/CDs obtained by the method shows a double-fluorescence-emission effect with 450nm blue light and 596nm red light in a visible region under the 365nm ultraviolet excitation. By utilizing different responses of double fluorescence on different water contentsin the organic solvent, different composite fluorescence color changes are displayed, so that double-fluorescence-emission test paper can be used for colorimetric detection on trace water in the organic solvent through naked eyes, the detection limit can be lowered to 0.02 percent (v/v), and convenience is provided for detecting the trace water in environmental protection, food safety and organicreaction.

An x-ray analysis apparatus for illuminating a sample spot with an x-ray beam. An x-ray tube is provided having a source spot from which a diverging x-ray beam is produced having a characteristic first energy, and bremsstrahlung energy; a first x-ray optic receives the diverging x-ray beam and directs the beam toward the sample spot, while monochromating the beam; and a second x-ray optic receives the diverging x-ray beam and directs the beam toward the sample spot, while monochromating the beam to a second energy. The first x-ray optic may monochromate characteristic energy from the source spot, and the second x-ray optic may monochromate bremsstrahlung energy from the source spot. The x-ray optics may be curved diffracting optics, for receiving the diverging x-ray beam from the x-ray tube and focusing the beam at the sample spot. Detection is also provided to detect and measure various toxins in, e.g., manufactured products including toys and electronics.

Networks of single-walled carbon nanotubes (SWCNTs) decorated with Au-coated Pd (Au/Pd) nanocubes are employed as electrochemical biosensors that exhibit excellent sensitivity (2.6 mA mM⁻¹ cm⁻²) and a low estimated detection limit (2.3 nM) at a signal-to-noise ratio of 3 (S/N=3) in the amperometric sensing of hydrogen peroxide. Biofunctionalization of the Au/Pd nanocube-SWCNT biosensor is demonstrated with the selective immobilization of fluorescently labeled streptavidin on the nanocube surfaces via thiol linking. Similarly, glucose oxidase (GOx) is linked to the surface of the nanocubes for amperometric glucose sensing. The exhibited glucose detection limit of 1.3_M (S/N=3) and linear range spanning from 10 μM to 50 mM substantially surpass other CNT-based biosensors. These results, combined with the structure's compatibility with a wide range of biofunctionalization procedures, would make the nanocube-SWCNT biosensor exceptionally useful for glucose detection in diabetic patients and well suited for a wide range of amperometric detection schemes for biomarkers.

The present invention is directed to an apparatus, a system and a method for detecting the presence or absence of trace elements in a biological sample using Laser-Induced Breakdown Spectroscopy. The trace elements are used to develop a signature profile which is analyzed directly or compared with the known profile of a standard. In one aspect of the invention, the apparatus, system and method are used to detect malignant cancer cells in vivo.

The invention discloses a low-concentration, multi-component and high-sensitivity gas detection method based on integration of multiple spectrum technologies. Advantages of an ultraviolet differential optical absorption spectroscopy (DOAS) technology and an infrared tunable diode laser absorption spectroscopy (IR-TDLAS) technology are integrated, so that information integration and characteristic signal extraction of two kinds of spectrum are realized. The method disclosed by the invention is used for measuring the NH3 concentration in smoke by utilizing a TDLAS method and simultaneously measuring the concentrations of SO2 and NO2 in smoke by utilizing an ultraviolet DOAS method; interference of three components in the NO absorbancy is removed according to the obtained concentrations and an interference spectrum of three kinds of gas to the NO absorbancy, so that the NO concentration without cross interference is solved; and thus, the measurement precision and the detection lower limit are greatly increased.

The invention relates to inspection and quarantine systems for biomedicine, agriculture, food hygiene and the like and particularly relates to an absolute quantification type digital nucleic acid analytic system based on an efficient liquid drop microreactor. The absolute quantification type digital nucleic acid analytic system is mainly used for detecting the molecular structure of nucleic acid so as to analyze attributes of organisms and belongs to the fields of biological and medical detection. The absolute quantification type digital nucleic acid analytic system comprises a confocal fluorescence image collecting system, a micro-fluidic chip, a temperature circulating heating system, an electric loading platform, an automatic sample feeding device, a controller and a computer. The formation and PCR amplification of micro-droplets are finished by virtue of the same micro-fluidic chip, namely the micro-fluidic chip has a droplet formation function and a PCR amplification (microreactor) function. According to the absolute quantification type digital nucleic acid analytic system, the complexity of the absolute quantification type nucleic acid analysis process is reduced, the nucleic acid analysis process is finished in a one-button manner, and culture and bacteria-proliferating processes are omitted, so that the rapid detection is realized, the sensitivity of the absolute quantification type nucleic acid detection is greatly improved, meanwhile, the sample consumption of the absolute quantification type nucleic acid analysis is substantially reduced, and the high throughput detection is realized.

The invention discloses an enzyme-free methyl parathion detection sensor, and preparation and application methods thereof. The sensor comprises a three-electrode system, wherein a graphene/carbon nanotube/chitosan deposition modified glassy carbon electrode is used as a working electrode, a platinum sheet is used as a counter electrode, and a calomel electrode is used as a reference electrode. In the detection process, by using the graphene/carbon nanotube/chitosan deposition modified glassy carbon electrode as the working electrode, the platinum sheet as the counter electrode and the calomel electrode as the reference electrode, an electrochemical work station is utilized to determine the content of methyl parathion. The enzyme-free methyl parathion detection sensor disclosed by the invention has the advantages of short preparation time and environment friendliness, is simple to operate, and can be recycled; and the low detection limit is 0.8ng/L. The invention also has the advantages of short sample detection time and simple treatment.

The invention discloses a chiral analysis method for nicotine in tobacco juice of an electronic cigarette. The chiral analysis method comprises the steps of diluting the tobacco juice of the electronic cigarette by a methyl alcohol/methyl tertiary-butyl ether solution, analyzing S-(-)-nicotine and R-(+)-nicotine in the tobacco juice of the electronic cigarette by using a chiral stationary phase capillary column mthrough a gas chromatograph-mass spectrometer, performing chiral analysis on the S-(-)-nicotine and the R-(+)-nicotine by comparing the retention time of a chromatographic peak and characteristic ions of nicotine in a standard sample with the retention time of a chromatographic peak and characteristic ions of nicotine in an electronic cigarette tobacco juice sample, and normalizing areas of quantitative ion peaks of the S-(-)-nicotine and the R-(+)-nicotine to quantify the proportions of the S-(-)-nicotine and the R-(+)-nicotine to the total nicotine. The chiral analysis method has the advantages that the nicotine in the tobacco juice of the electronic cigarette is separated by a chiral stationary phase capillary column, so that the S-(-)-nicotine and the R-(+)-nicotine in the nicotine can be better separated, and accurate and quantitative analysis on the nicotine can be realized. The sample treatment is simple and convenient; the chiral analysis method is low in detection limit, high in sensitivity, high in reproducibility, accurate in quantification and suitable for chiral analysis on the nicotine in a large batch of electronic cigarette tobacco juice samples.

Devices, materials and methods for the detection of one or more target analytes, particularly volatile organic compounds (VOCs) in air or other gases. Point sensors and sensor arrays for the detection of one or more of such analytes in air or other gases. Sensors employ the detection of IR absorption of wavelengths characteristic of a target analyte or a class of target analytes to detect the presence of and/or measure the concentration of one or more target analytes in air or other gases. Sensors employ sorbent layers into which one or more of the target analytes are adsorbed from the air or other gases to be analyzed. Preferred sorbent layers comprise polymer sorbents, metal oxide sorbents or mixtures thereof.

The invention relates to a doped nano sensitive material for monitoring benzene, which is characterized in that: the doped nano sensitive material consists of Ag atom-doped TiO2, Fe2O3 and Al2O3 powder, wherein the content ranges of the components are that: the content range of Ag is 10 to 12 percent, the content range of TiO2 is 30 to 40 percent, the content range of Fe2O3 is 25 to 35 percent, and the content range of Al2O3 is 15 to 25 percent; and the grain diameter is less than 30nm. Benzene sensors prepared from the sensitive material provided by the invention have wide linear range, goodselectivity and high sensitivity, can monitor micro benzene in the air on line, and are not influenced by coexisting substances.

The invention discloses a probe compound for identifying fluorine ions by combining spectral detection and bare eyes. The compound is a new compound formed by using excited state proton transfer compounds as a matrix and by silylation. The compound can be used for detecting fluorine ions, in particularly detecting fluorine ions in a water environment. Infiltrated test paper prepared by the compound is quick and convenient, the detection limit is low, and according to different excited wavelengths, two modes, namely an intensity identification mode and a chromaticity identification mode, can be selected respectively for better detection by an instrument and bare eyes.

The invention relates to a preparation method of a fluorescent molecular probe for detecting sulfite ions through naked eyes and fluorescence ratio as well as the application of the fluorescent molecular probe in detecting sulfite ions. The fluorescent molecular probe is prepared by condensing 4-hydroxy naphthalimide serving as raw material and acetylpropionic acid in refluent methylene dichloride. The synthesis is simple and convenient, and the reaction conditions are mild. The probe molecule provided by the invention has higher sensitivity, stable fluorescence performance, higher synthesis yield and good selectivity, and furthermore, the response range of the probe is 0-1500 mu m, the detection limit is 6 mu m; the detection range is wide, the lower detection limit is low, and the probe is suitable for naked eye detection. Meanwhile, the florescence-ratio detection is adopted to avoid errors caused by exciting light intensity, probe concentration and environment factors of an off-on type probe which detects ions only depending on the change of fluorescence intensity and the probe disclosed by the invention is not influenced by anions such as F<->, Cl<->, Br<->, I<->, HPO4<2->, SO4<2->, NO<3->, AcO<->, ClO<4->, N<3-> and HCO<3->. Even interfering ions exist, the probe has very good response to sulfite ions. Therefore, the fluorescent molecular probe has practical application value in the fields of biochemistry, environmental science and the like.