37results about How to "Suitable for determination" patented technology

The invention relates to a method for testing tobacco water content based on a time-domain nuclear magnetic resonance inversion peak area. The method is characterized in that a CPMG sequence is used on a time domain time-domain nuclear magnetic resonance, 4-6 of the tobacco standard samples with different qualities are measured, a transverse relaxation spectrum of the standard sample is obtained by SIRT inversion of an original data, a primary peak area of the transverse relaxation spectrum is recorded, the water content of the standard sample is measured by using a microwave drying method, a standard curve of the primary peak area data and the water content of the standard sample is established, the sample with water content to be measured is measured, the obtained primary peak value is substituted into the standard curve, the water content of the to-be-measured sample is obtained, and the water content of the to-be-measured sample is obtained. The interference of an oil signal in a tobacco sample can be eliminated, influence of oil fraction in the tobacco is not generated, detection speed is fast, and the result is accurate. The sample preparation and solvent consumption are not required, the defect that the oil and water signals in the tobacco cannot be distinguished when a nuclear magnetic signal method is used for measuring water content of the tobacco, and the accuracy for measuring the water content of the tobacco oil-water signal sample is increased.

The invention relates to the technical field of physical and chemical inspection of water-based glue and particularly relates to a method for determining three types of isothiazolinone preservatives in water-based glue by adopting a liquid chromatography-tandem mass spectrum. A water-based glue sample is extracted with water and centrifuged, then is subjected to LC-MS/MS analysis and is quantified by an internal standard method. The concentration range of 2-methyl-4-isothiazolin-3-ketone (MI) and 5-chloro-2-methyl-isothiazolin-3-ketone (CMI) is 2.5ng/mL-250ng/mL, the concentration range of 1,2-benzisothiazol-3(2H)-ketone (BIT) is 5ng/mL-500ng/mL, the linear relation is good (R2 is more than or equal to 0.9996), the adding standard recovery rates of three adding levels are 96.3%-109.6%, the average relative standard deviation (RSD) is 1.5%-6.7%, and the limit of detection (LOD) and the limit of quantification (LOQ) of the method are 0.011mg/kg-0.015mg/kg and 0.035mg/kg-0.051mg/kg. The method is simple to operate, has high sensitivity and good repeatability, and is suitable for rapidly determining MI, CMI and BIT in the water-based glue.

The invention discloses a sample pretreatment method for detecting special nitrosamine in tobacco and tobacco products by LC-MS/MS (liquid chromatogram-mass spectrum/mass spectrum). The sample pretreatment method comprises the following steps of: (1) preparing ammonium acetate buffering solution; (2) drying and crushing the tobacco and tobacco products; (3) adding the ammonium acetate buffering solution in the crushed sample, and ultrasonically extracting; (4) carrying out high-speed centrifugation on the extracted sample at room temperature to obtain a first supernatant; (5) adding ethyl acetate in the first supernatant and carrying out extraction and purification, and then centrifuging to obtain a second supernatant; (6) taking the second supernatant, blow-drying by nitrogen and redissolving by deionized water to prepare sample to be detected; and (7) detecting tobacco special nitrosamine in the sample to be detected by virtue of LC-MS/MS. The sample pretreatment method disclosed by the invention has the advantages that the sample pretreatment method is simple and practicable; the tobacco special nitrosamine is dissolved out by the ammonium acetate buffering solution, and purified by the extraction of ethyl acetate solution, and proteins and interference substances are removed to obtain refined sample solution after impurity removal, thus the sample detection is high in accuracy, high in extraction efficiency, simple and convenient to operate, time-saving, and low in reagent consumption.

The invention discloses a gas chromatograph and detection method for determining the total content of sulfides in natural gas. The gas chromatograph comprises a quartz capillary column, a hydrogen flame ionization detector, a temperature control unit and a sulfur chemiluminescence reactor which are successively connected, wherein the quartz capillary column is a fused silica capillary column with uncoated inner walls; and the gas chromatograph further comprises a processor which is connected with the sulfur chemiluminescence reactor and a display unit. The gas chromatograph and detection method provided by the invention eliminate influence of hydrocarbons on determination of sulfide content, are more accurate in testing and have a wider application scope.

The invention relates to a pesticide biological activity testing method that uses Cyclops as acting object. In slight amount vessel, the sensitivity of the sample would be used to take insecticidal activity test by Cyclops. The method is easy to operate and is suited to test biology of slight amount sample. The method could be used to test the activity of the existing variety and research the new pesticides.

The invention discloses a method for measuring solvent compositions in nicotine liquid by combining gas chromatography and mass spectrometry. The method comprises the following steps of preparing a series of standard solutions simultaneously containing ethanol, 1,2-propylene glycol, glycerin, diethylene glycol, triethylene glycol, tetraethylene glycol and pentaethylene glycol by taking a methanol solution of 1,3-butylene glycol as an internal standard solution which serves as a solvent, detecting the series of standard solutions by utilizing gas chromatography-mass spectrometer, and establishing a standard curve; pre-treating the nicotine liquid to obtain a sample solution to be detected, detecting the sample solution to be detected by utilizing the gas chromatography-mass spectrometer, and calculating the solvent compositions in the nicotine liquid according to the corresponding standard curve. According to the method, ethanol, 1,2-propylene glycol, glycerin, diethylene glycol, triethylene glycol, tetraethylene glycol and pentaethylene glycol in a smokeless tobacco product can be simultaneously detected, and the method is easy to operate and high in sensitivity and reproducibility.

The invention discloses a method for measuring three isothiazolinone preservatives in cigarette paper by liquid chromatography-tandem mass spectrometry, comprising the following steps: (1) preparing amixed standard solution containing three isothiazolinones, and carrying out quantitative analysis by an internal standard method to obtain a standard curve linear regression equation; (2) cutting a sample into a square with side length being 0.4-0.6 cm, weighing and taking cigarette paper to be measured into an Erlenmeyer flask, adding water and an internal standard solution, carrying out ultrasonic extraction, and filtering through a 0.22-micron water-phase filter membrane to obtain a sample solution to be measured; and (3) analyzing the sample solution to be measured by liquid chromatography-tandem mass spectrometry, and respectively calculating according to the standard curve linear regression equation so as to obtain concentrations of the three isothiazolinones. The analytic method for simultaneously measuring contents of three isothiazolinones in cigarette paper is fast to operate, is simple and feasible, has advantages of stable response, environmental solvent and high extraction efficiency, and can avoid liquid chromatographic solvent effect caused by methanol extraction and sample introduction.

The invention discloses a pre-concentration-gas chromatograph and a detection method for measuring the content of a sulfide in hydrogen. The gas chromatograph comprises a first-stage cold trap, a second-stage cold trap, a third-stage cold trap, a quartz capillary chromatographic column column, a sulfur chemiluminiscence detector, a signal processor, and a display device, which are connected with each other in sequence. The detection method comprises the following steps: performing a three-stage desorption treatment of a hydrogen sample, and conveying the treated sulfide into the fused quartz capillary chromatographic column column with an uncoated inner wall; conveying the pre-concentrated sulfide into the sulfur chemiluminiscence detector through the fused quartz capillary chromatographiccolumn column with the uncoated inner wall; and receiving and processing, by the signal processor, the signal transmitted by the sulfur chemiluminiscence detector, and obtaining a corresponding chromatogram on the display device. The pre-concentration-gas chromatograph disclosed by the invention has a wide application range, is suitable for measuring various sulfocompounds in the hydrogen, and can be used for the impurity analysis in the GB/T 37244 "Fuel Hydrogen For Proton Exchange Membrane Fuel Cell Vehicle".

The invention relates to a wine fried herba siegesbeckiae detection method, which is performed by using UPLC/Q-TOF-MS. The detection method has characteristics of simple operation, short time consuming and significant distinction.

The invention belongs to the field of nonferrous metallurgy, in particular to a method for improving the accuracy and precision of trace amount antimony in metal lead measuring. The method comprises the following steps: (1), preparing the following solution; (2), drawing the standard solution working curve; and (3), analyzing samples and finding out corresponding antimony concentration from the working curve. The method has the following advantages: (1), a technology is provided for improving the accuracy and precision of trace amount antimony in metal lead measuring; (2), full amount extraction is realized; (3), the method has high result accuracy, high precision and good repeatability; no light absorption value variation triggered by diversity of the extraction sequence or storage period during the measurement between standard curve series point solution and sample solution is caused; (4), the method is also suitable for the measurement of antimony in lead alloy; and (5), only simple and convenient spectrophotometer is used, the cost is low, and the method is particularly suitable for production units.

A method for determining TOPO content in an organic solvent by employing capillary gas chromatography comprises the following steps: (1) connecting apparatuses; (2) setting apparatus parameters; (3) drawing a calibration curve; and (4) detecting a to-be tested sample: (a) performing centrifugation separation on a to-be tested solution or employing PS paper to filter to remove water and suspend solids; (b) accurately weighing 2 g of didecyl phthalate, putting in a 50 mL of a volumetlric flask, transferring 25 mL of the clear solution to a same volumetlric flask by employing a pipet, and setting the volume with hexane; (c) according to gas chromatography conditions to inject the sample with sample injection amount of 1.0 mu L and 0.5 mu L for multiple times, and obtaining the peak area ratio and the peak height ratio of the sample to an internal standard substance from the chromatogram; and (d) according to an internal standard calibration curve to find the mass ratio of the sample to the internal standard substance, and calculating the content. Didecyl phthalate is selected as the internal standard substance, and the peak height internal standard method and the peak area internal standard method are employed. The relative standard deviation of the peak area internal standard method is 0.31%, the linearly dependent coefficient is 1.0000, the detection limit is 0.0014 g/mL, and the method is simple, rapid, good in repeatability and applicable to determination of trace ingredients.

The invention relates to a method for determining the content of lead in a silver alloy and belongs to the technical field of analytical chemistry. The method comprises dissolving a sample through nitric acid, adding sulfuric acid into the solution so that the lead forms lead sulfate precipitates and is separated, and carrying out titration in an acetic acid-sodium acetate buffer solution to meteron the lead content of the alloy through EDTA. The method is simple and rapid, has a wide measuring range, realizes accurate measurement, compensates for the blank of high-content lead analysis in the silver alloy, provides the technical support for analysis and determination of silver products in the precious metal field, is suitable for testing and analysis of large-volume samples, and can be widely applied in the ore test and analysis field.

The invention discloses a method for simultaneously and rapidly determining various organophosphorus in vegetable oil by combining dispersive liquid-liquid microextraction with gas chromatography, which belongs to the field of analytical chemistry. The method specifically comprises the following steps of: (1) preparing a mixed standard solution; (2) extracting a sample; (3) carrying out dispersive liquid-liquid microextraction; (4) carrying out gas chromatographic analysis; and (5) formulating a standard working curve and performing quantitative analysis. In the detection process, a large amount of organic solvent is not needed, and the method is green, environment-friendly, rapid, efficient, high in detection result sensitivity and good in reproducibility.

The invention relates to a method for measuring sand content of sludge. The method comprises the following steps of drying sludge generated by a sewage treatment plant and measuring water content of the sludge; accurately weighing the dried sludge and burning in a muffle surface to constant weight; adding concentrated acid into the sludge which is burned to constant weight and heating in water bath to react; filtering a reacted solution through quantitative filter paper and fully washing filter residue clean through deionized water; putting the filter residue and the quantitative filter paper into the muffle furnace to be burned to constant weight to obtain pure sand; obtaining the sand content of the sludge through calculation. The method can quickly and accurately measure the sand content in the sludge, provides theoretical basis for urban sludge treatment and has wide application prospect in the fields of environmental protection, solid waste treatment and utilization and the like; the method is safe and simple and has moderate conditions and accurate and stable data; an operation process is easy to control; furthermore, a technological requirement is not high; the method is suitable for accurately measuring the sand content in the sludge for a long time.

The invention discloses a method for testing zirconium oxide in a zirconium oxide coated nickel-cobalt-manganese ternary positive electrode material, and can solve the technical problems of more interference factors and larger errors in the existing method. The method comprises the following steps: dissolving a nickel-cobalt-manganese ternary positive electrode material sample by hydrofluoric acidand nitric acid; adding cesium chloride into the sample solution, transferring the constant volume sample solution into a separating funnel, adding an n-hexane solution containing 55% of trimethyl phosphate for extraction separation, and taking the separated organic phase solution as a to-be-detected sample. According to the invention, the 1.5% cesium chloride solution is selected to inhibit ionization of zirconium at high temperature of nitrous oxide-acetylene flame, and the test sensitivity of zirconium is improved. A normal hexane solution containing 55% of trimethylphosphate is used for extraction, main metal and zirconium metal ions are separated according to different combining capacities of various metals and an extracting agent, and the types of anions are changed, so the interference of the nickel-cobalt-manganese main metal in the nickel-cobalt-manganese ternary positive electrode material on zirconium metal testing is reduced, and the testing accuracy is improved.

The invention provides a method for detecting the content of acetonitrile in a composite solid propellant by using gas chromatography. The method comprises the following steps: preparing an internal standard solution, preparing a to-be-detected sample solution, selecting gas chromatography detection conditions, drawing a correction curve and detecting a to-be-detected sample. According to the invention, the content of the residual acetonitrile in the composite solid propellant can be accurately detected, and the method is good in measurement effect, accurate in measurement, simple, convenient, rapid, good in repeatability and suitable for measurement of trace components.