116results about How to "Good linear correlation" patented technology

The invention relates to a method for detecting the content of trace elements in cheese, which comprises the following steps of: 1) weighing a cheese sample and drying the sample for completely evaporating the water in the sample, then weighing the sample after drying and utilizing the weight difference of the sample before and after the drying to calculate the water content in the sample, and then taking the dried sample for being grinded and homogenized, adding acid for dissolving the dried sample, and adding suspension stabilizer for even mixing and stable dissolving, thereby obtaining solution to be detected; and 2) utilizing inductive coupling plasma emission spectroscopy or atomic absorption spectrometry for detecting the content of trace elements in the solution to be detected. By adding the suspension stabilizer, the solution is suspended stably, thereby achieving the purpose of leading the solution to be homogeneous. The detection method is simple, rapid and accurate, and has high-sensitivity.

The invention discloses a method for testing the content of benzene and benzene series in a water base adhesive for tobaccos. The method comprises the following steps of: preparing internal standard matrix correction liquid, standard working solution and sample solution; performing static headspace gas chromatography and mass spectrometry analysis; drawing a standard curve, calculating a result and the like. The improved and optimized detection method has the advantages of simplicity and accuracy in operation, high sensitivity, high recycling rate, high repeatability and the like. In the method, fluorobenzene is used as an internal standard for internal standard quantitative detection, so that errors caused by a sample preparation process, different sample injection quantities or different instrument precision and the like can be reduced effectively; and under the adopted chromatographic condition, the separation degree of five target compounds and an internal standard chromatographic peak is high and higher linearity relevance is high; and the detection limit is 0.40 to 0.84mu g/kg, the quantitation limit is 21.32 to 2.79mu g/kg, the marking recovery rate is 95 to 101 percent, and the average relative standard deviation is 0.91 to 2.46 percent.

The invention discloses a method for measuring formaldehyde and acetaldehyde content in paper for a cigarette at the same time, which comprises the following steps of: preparing a mixed standard stock solution; preparing a standard working solution; creating a standard working curve; preparing a derivatization reagent; preparing a sample solution; analyzing by ultra high performance liquid chromatography; and calculating a result. According to this method, a sample processing method and the chromatographic condition are improved and optimized, so that two compounds to be measured have good separation effect and good peak shape. A scanning operation is carried out by employing two wavelength channels at the same time, so that this method has obvious advantage in sensitivity in comparison with single wavelength measurement at the same time. The ultra high performance liquid chromatography is employed, so that analysis time is greatly shortened. The two compounds to be measured both have better chromatographic peak separation and better linear correlation, the detection limit of the formaldehyde is 0.57mg/kg and the detection limit of the acetaldehyde is 0.34mg/kg. In the method, the recovery rate of the formaldehyde is 98.14%, the recovery rate of the acetaldehyde is 97.55% and the average relative standard deviations of the formaldehyde and the acetaldehyde are both less than 2.5%.

The invention discloses a method for measuring the content of benzene and benzene series in hot melt glue. The method comprises the following steps of: selecting benzene, methylbenzene, ethylbenzene, o-xylene, p-xylene or m-xylene as standard substances of the benzene and the benzene series, and gradually diluting to form a standard working solution by taking glyceryl triacetate as a matrix correction fluid; taking a hot melt glue sample and adding the hot melt glue sample into the matrix correction fluid, and detecting and analyzing the standard working solution and the sample by using a headspace gas chromatography mass spectrometry; and finally, drawing a standard curve and calculating a result. In the invention, a complex pretreatment process of the sample, and influences and interference caused by volatile components in the sample are eliminated. According to the method, the recovery rate ranges from 95% to 101%, the average relative standard deviation ranges from 3.04% to 4.14%, and the repeatability is good.

The invention relates to a method for preparing ammonium sulfamate bacterial celluloses for absorbing Pb2+ in waste water. The method includes the steps of (1) preparing bacterial celluloses, wherein the process includes the steps of (a) cultivation of the bacterial celluloses, (b) isolation and purification of the bacterial celluloses and (c) preparation of bacterial cellulose powder; (2) preparing epoxidation bacterial celluloses, wherein the process includes the steps of (a) preparation of alkalization bacterial celluloses and (b) obtaining of epoxy group bacterial celluloses; (3) preparing the ammonium sulfamate bacterial celluloses. By means of the method, the ammonium sulfamate bacterial celluloses serve as absorption materials of the Pb2+, the absorption process is rapid, adsorption equilibrium is achieved at the 90 min in the absorption process, the good linear dependence is achieved, and the theory saturation adsorption amount of the ammonium sulfamate bacterial celluloses is 31.23 mg/g.

The invention relates to a method for measuring 3-acetyl-2, 5-dimethyl thiophene in edible flavor and fragrance. The method comprises the steps of selecting an absolute ethyl alcohol ultrasonic extraction sample containing an internal standard for use in the pretreatment process, enabling extract liquor to directly enter a gas chromatograph-mass spectrometer for measurement after the extract liquor passes through a filtering membrane, detecting in an ion mode, and quantifying by an internal standard method. The method for measuring 3-acetyl-2, 5-dimethyl thiophene in edible flavor and fragrance by the gas chromatograph-mass spectrometer is simple in sample treatment, easy to operate, low in detection cost, good in repeatability and high in recovery rate, and is capable of rapidly and accurately measuring the content of 3-acetyl-2, 5-dimethyl thiophene in flavor and fragrance in batches; furthermore, harmful and toxic chemicals are not used in the experiment process, so that the method is less in harm to an operator and free from pollution to environment.

The present invention provides a liquid chromatography-tandem mass spectrometry method for detection of specific total migration of nine ultraviolet absorbers. The method is as below: soaking a sample to be measured in a food simulant, cooling to room temperature and mixing well; diluting the water-based food simulant with ethanol by 1:10, filtering by a hydrophilic PTFE filter and introducing the sample; extracting the olive oil with acetonitrile n-heptane, and filtering the lower clear liquid with a hydrophilic PTFE filter and introducing the sample; Conducting gradient elution and separation by a C8 column; and running under negative multiple reaction monitoring mode by using a mass spectrometry with electro-spray ionization source. The method has good chromatographic separation and linear relationship, high recovery and accuracy, meets the limit requirements on specific total migration of the 9 ultraviolet absorbers in EU regulations (EU) NO 10/2011, and has been applied to actual detection of samples.

The invention discloses a method for quantitatively analyzing lactones aromatic substances in mainstream smoke of fine cigarettes. The method is used for determining the content of three types of main lactones aromatic substances including alpha-angelica lactone, gamma-caprolactone and dihydroactinidiolide in the mainstream smoke of the fine cigarettes based on a gas chromatography-tandem mass spectrometer, and comprises the steps of preparing an internal standard solution, a standard working solution and a sample solution, analyzing by the gas chromatography-tandem mass spectrometer, and calculating a determined result and the like. The optimized detection method disclosed by the invention is relatively simple and convenient, and sensitive to respond and can be used for accurately quantitatively analyzing; matrix interferences are effectively avoided, and the linear correlation is relatively good; the detection limits of the three types of main lactones aromatic substances including the alpha-angelica lactone, the gamma-caprolactone and the dihydroactinidiolide are 4.23ng/piece, 1.86ng/piece and 1.87ng/piece respectively, the repetitive rates are 1.31%, 3.57% and 1.93% respectively, and the standard recovery rates are 108.3%, 115.4% and 89.4% respectively. The method disclosed by the invention has high sensitivity and relatively good repeatability and recovery rate, and is applicable to quantitative analysis of trace target matters in complicated matrixes of the smoke of the fine cigarettes.

The invention relates to a method for detecting molybdenum element in milk powder. The used equipment is an inductively coupled plasma atomic emission spectrometer. The method has the following steps of: 1) preparing molybdenum element standard solution and making a standard curve according to the standard solution; 2) oxidizing a milk powder sample to be tested by using peroxide, performing acid treatment by using nitric acid, digesting in a microwave digestion system, and detecting by using equipment parameters same as the standard solution to obtain a detection result of the sample to be tested; and 3) comparing the detection result of the sample to be tested with the standard curve to determine the content of the molybdenum element in the sample to be tested. The instrument detection limit of the method is 0.0071 mu g/ml, and in an element linear range, the related coefficient r is over 0.999, and the recovery rate is 92.0 to 101.8 percent. The method can quickly and accurately detect the content of the molybdenum element in the milk powder, and has the advantages of low element loss and pollution probability in the sample preparing process, accurate and reliable result, good repeatability and high sensitivity.

The invention provides a multilevel structure metal oxide gas sensitive material and a preparation method thereof. Urea or hexamethylenetetramine is used as an alkaline source, the increase rate of the pH value of a reaction system is retarded in virtue of an organic acid as a structure-directing agent, a water and alcohol mixed solvent is used for adjusting the growth kinetics of a wafer, a multilevel structure layered hydroxide precursor assembled by nanosheets is prepared, a multilevel structure complex oxide assembled by the nanosheets is obtained through roasting, then porous nanosheets are obtained by etching MgO or ZnO in the complex oxide through ammonium salt, more surface defects are formed, and the porous multilevel structure metal oxide gas sensitive material with low operationtemperature, high response value and low detection limit is obtained. The thicknesses of the nanosheets of the material are 5 to 20 nm, the specific surface area is 80 to 180 m<2>/g, the pore diameter is concentrated to be 2 to 15 nm, the gas adsorption, diffusion and activation are promoted, and then the gas sensitive material is improved. The method provided by the invention is simple in operation, mild in condition and convenient for industrial production.

The invention relates to a method for detecting a zinc element in yolk powder, which comprises the following steps of: 1) preparing standard zinc solution of which concentration is 0.1 mu g/ml to 1.0 mu g/ml, and making a standard curve according to the standard solution; 2) weighing, heating and drying a yolk powder sample to be detected, dissolving the dried yolk powder sample into a 5 volume percent hydrochloric acid, adding agar solution of which the concentration is 3 percent, well shaking the mixed solution and then performing detection with equipment parameters the same as those in the detection of the standard solution to obtain a detection result of the sample to be detected; and 3) comparing the detection result of the sample to be detected with the standard curve to determine the content of the zinc element in the sample to be detected. Detection equipment used in the method is an atomic absorption spectrophotometer. In the detection method, instrument detection limit is 0.03 mg/kg, and in a linear range, a related coefficient r of the element is over 0.999 and a coefficient of recovery is 95.1 to 100.2 percent. The detection method of the invention has the advantages of simple steps and accurate and reliable result.

The invention discloses a method for measuring content of benzene and benzene series in glycerol triacetate. The method comprises the following steps: preparing a standard working solution, analyzing by gaschromatographic mass spectrometry, drawing a standard curve, calculating a result, etc. After the improvement and optimization, the detection method has the advantages of simplicity, accuracy and sensitivity in operation, high recovery rate, good repeatability and the like. 2-hexanone is used as an interior label, so that by adopting the interior label quantitative detection, errors caused by the preparation process of a sample, different sample loading amounts or instrument precision and the like can be effectively reduced; the adopted chromatographic condition enables the separation degree of six target compounds and interior label chromatographic peaks to be better; moreover, the linear correlation property is better. The detection limit is 0.01 microgram/gram to 0.02 microgram/gram, the quantitative limit is 0.04 microgram/g to 0.06 microgram/gram, the loading recovery rate is 94 percent to 104 percent, and the average relative standard deviation is within 7 percent.

The invention belongs to the technical field of water environment chemical analysis, and particularly relates to a local coulomb method for measuring biochemically degradable organic matters in a water body. According to the method, uniquely a fastest voltage reduction point is selected as a cut-off point for collecting a voltage; the cut-off point is easy to find, and the measurement time can begreatly shortened, so that the operation efficiency is improved; by means of the local coulomb method of the cut-off point selection method, the linear correlation between the value of oxygen consumption BOMQ1 in a measurement result and the concentration of a GGA standard solution for culture of electricigens is better, the more scientific, reasonable and accurate test method is provided for measuring the biochemically degradable organic matters in the water body by utilizing a microbial fuel cell, and new idea and direction are provided for scientific control of water environment pollution;and the method has great popularization values and wide application prospects.

The invention provides a method for detecting advanced glycation end-products (AGEs) in an aquatic product by using liquid chromatography-tandem mass spectrometry. The method comprises the following steps of: 1, extracting AGEs; 2, making a standard curve: drawing the standard curve by taking the concentration value of a standard substance as the abscissa and taking the standard substance area*(internal standard substance concentration/internal standard substance area) as the ordinate to obtain an equation; and 3, subjecting the treated sample to HPLC-MS/MS detection in a detection mode of MRMto obtain the AGEs peak area in the sample, and acquiring the AGEs concentration in the sample. The invention aims to establish the liquid chromatography-tandem mass spectrometry method, which can detect three AGEs (carboxymethyl lysine (CML), carboxyethyl lysine (CEL) and methyl glyoxal hydroimidazolone MG-H1) at one time and has the advantages of good separation degree, good linear relationship, wide linear range and the like.

The invention provides a signal-enhanced type near infrared fluorescence probe, wherein the chemical structural formula is shown as FORMULA (1); in Formula (I), X1 is -S or -Se-, R' is C1-12 alkylene, X2 is -C(CH3)2-, -O-, -S- or Se-; R1 and R2 are independently selected from H atom, C1-18 alkyl or radical groups shown in SO3R5, wherein R5 is C1-18 alkyl or benzyl; R3 and R4 are independently selected from C1-18 alkyl or benzyl; Y is fluorine, chlorine, bromine or iodine. The activating and emitting lights of the probe are located in the near infrared zone; the stocks displacement is big, the background disturbance is few; the probe has high sensitivity and high selectivity for sulfur alcohol; meanwhile, the probe is low in toxicity, small in harm of cell and living body, and very suitable for detecting sulfur alcohol in a biological body. The invention further provides a preparation method of the probe and an application thereof.

The invention relates to a method for detecting geraniol in flavors and fragrances. According to the method, geraniol is measured by adopting liquid chromatography tandem mass spectrometry, and quantification is performed by adopting an external standard method. The detecting method has the advantages of short detection time, easiness and convenience in operation, high sensitivity and recovery rate and good repeatability. Due to the chromatographic conditions of the method, the chromatographic peak of geraniol is separated from the impurity chromatographic peak well, the method has a good linear range, the detection limit is 0.001 microgram/mL, the recovery rate is 90.8%-98.3%, and the relative standard deviation (RSD) is smaller than 5% (n=6).