256 results about "Standard addition" patented technology

The invention relates to a method for using a plasma atomic emission spectrometer to measure impurities in high-purity gold, which comprises the following steps: weighing one unit of sample in a bunsen beaker, adding aqua regia to dissolve, replenishing hydrochloric acid deionized water to do constant volume to a scale after dissolving, respectively getting sample solution in more than two colorimetric tubes, solution in each tube is 15ml, adding gold standard solution which is mixed by elements according to a multiple relation in turn, doing constant volume by deionized water, starting the plasma atomic emission spectrometer, starting a circulating water pump, opening analytic control software, entering a 'standard addition method' control procedure, choosing a spectral line for measuring in a spectral line base, setting the concentration value of curved lines, scanning a whole band, sucking sample solution in each colorimetric tube in an instrument in turn according to the sequence that the concentration is from low to high, clicking a feeler switch to get an initial curve point of the point after sucking in each time, assuring curved lines, and leading the linear coefficient to be more than 0.99, outputting the concentration value result of each determined element, and calculating the result of the percentage content of each determined element according to the calculating formula.

A method consists in measuring ac impedance spectrum using gold, platinum or carbon working ultramicroelectrodes (1). The direct current DC potential pulse which overlaps with alternating current AC signal of an amplitude in the range from 0.005 to 0.015 V and frequency in the range from 10<-2 >to 10<6>, Hz is applied at the electrode. The value of said DC potential pulse for a process of copper electrorefining is in the range from -0.4 to -0.9 V in relation to a platinum reference electrode (2). Resistance values characteristic of a given electrolyte (E) are obtained from said AC impedance spectrum and compared with standard characteristic obtained by standard additions method. A measuring system consist of electrodes (1, 2, 3) placed inside a measuring cell (4) filled with flowing industrial electrolyte. The electrodes (1, 2, 3) are joined to a spectrum analyser (12) controlled by a programming apparatus (13)

The invention relates to a fast extraction, purification and detection method for Sudan red dye residues in food. The food is one of eggs, chilies and chili oil. The method comprises the following steps: an egg sample or a chili sample is extracted with acetonitrile-dichloromethane mixed liquor and then purified with a strong cation solid-phase extraction column, while a chili oil sample is mixed with dichloromethane-n-hexane and directly purified with the column; and detection is performed with UFLC-MS/MS (ultrafast liquid chromatography tandem mass spectrometry). The method overcomes the defect of low recovery rate of Sudan red III and Sudan red IV, solves the problems that the egg sample is dispersed easily and effective solid-liquid separation cannot be realized easily, and has the advantages of simple steps and convenience in operation; meanwhile, purified liquor after treatment is subjected to Sudan red content detection with the UFLC-MS/MS, the defects of poor sensitivity, low accuracy, high false positive rate and the like of the conventional liquid chromatography are overcome, the recovery of standard addition of four Sudan red dyes is 90.6%-99.4%, and the detection limit is 0.1-0.5 mu g/kg.

The invention relates to a method for rapidly and simultaneously determining the content of major element titanium and minor elements, namely, silicon, aluminum, manganese, nickel, vitriol, molybdenum, chromium, phosphorus and copper in 70 ferrotitanium through microwave digestion-ICP-AES. The method comprises the steps that a sample dissolving method, the microwave digestion conditions and the matrix interference condition are investigated and researched, an IEC data model is incorporated into method establishment, interference of the major element Ti to the trace element P can be sheltered, and the interference degree is decreased to minimum; detection limits of all the elements are determined finally, and a precision experiment and a standard addition recovery experiment are conducted. It is shown through the result that for the method, the relative standard deviation (n=8) ranges from 1.24% to 6.72%, and the standard addition recovery rate ranges from 92.6% to 105.1%. The method is advanced and reliable, the analysis cycle is short, ten elements can be determined rapidly and simultaneously through one-time sample decomposition, synchronous analysis of the major element and the minor elements is achieved successfully, and the method is suitable for analysis of 70 ferrotitanium.

The invention discloses an analysis method for amide compounds. The analysis method adopts a gas chromatography-mass spectrometry method. According to the invention, under the optimized analysis conditions, very good chromatographic peaks of the five amide compounds can be obtained within 15 min; very good separating effects can be obtained; the linearities of all the target compounds are good within a concentration range of 0.01-10 mg/L; the correlation coefficients are all greater than 0.9995; the detection limits reach 0.01 mg/kg; the relative standard deviations are smaller than 2.5%; the recovery rates of standard addition are 80-105%. The analysis method is convenient, fast, accurate, and reliable, and can meet REACH regulation requirements on hazardous amides.

The invention belongs to the field of product quality detection and in particular relates to a rapid detection method of residual amount of dimethylformamide in textiles. The method provided by the invention comprises the following steps of: preparing a guide sample and an internal standard solution; pre-treating the sample; extracting DMF (Dimethyl Formamide) in the sample; carrying out GC/MS (Gas Chromatograph/Metabolic Syndrome) analysis; and detecting the content of DMF through a standard addition method. The method provided by invention can be used for detecting the residual amount of DMF in products including leather, textiles, paper products and the like and various raw materials. Compared with the prior art, the method disclosed by the invention has the advantages of flexibility, accuracy, environment friendliness, simplicity, reliability and easiness of being popularized and is highly effective in detection of the residual amount of DMF in various products and raw materials.

The invention provides a fast detection method of benzo(a) pyrene in high-fat foods, relating to a detection method of benzo(a) pyrene, which has simple and fast operation and low cost. The method comprises the following steps of: placing a sample of high-fat foods in a ground suction bottle, adding a potassium hydroxide-methyl alcohol solution and normal hexane, extracting together with water in a microwave oven, taking out, cooling, flushing, taking out a clear liquid of normal hexane after settlement and stratification, drying by rotary evaporation, and determining the volume by using dichloromethane to obtain a sample solution to be detected; mapping the constant energy synchronous fluorescence spectra of the sample solution to be detected by using a fluorescence spectrophotometer with derivative-constant energy synchronous scanning for the identification and the rough detection of benzo(a) pyrene; and adding a second derivation function, mapping second derivate-constant energy synchronous fluorescence spectra, reading data by adopting a derivate baseline method, and determining the quantity of benzo(a) pyrene in the sample solution to be detected by using a continuous standard addition method.

A new method to determine by quantitative analysis the amount of dye present in dyed engine oils is provided. The method uses imaging techniques, such as spectrophotometry, and a combination of dilution and standard addition techniques to quantitatively determine the concentration of dye in the engine oil to ascertain whether dye concentrations in engine oil have decreased as compared with original specifications, and to quantify the amount of dye to be added to the dyed engine oil to bring dye concentrations to original concentrations.

The invention relates to a method for measuring phosphorus content in chromite. According to the method, a chromite sample is decomposed by high-temperature alkali fusion of sodium peroxide, the melt is extracted by hot water, phosphorus co-precipitates with elements such as iron, magnesium, manganese and the like, chromium enters the solution in a form of CrO4<2->, sodium hydroxide solution is used for washing so as to remove the chromium. The precipitate is subjected to acidolysis by hydrochloric acid and the precipitate subjected to acidolysis is then transferred into a volumetric flask. The test solution is separated, the pH value of the solution is adjusted by taking paranitrophenol as an indicator, phosphorus-molybdenum heteropoly acid is reduced to be phosphomolybdenum blue by taking ascorbic acid as a reducing agent in hydrochloric acid medium, and the light absorption value of the test solution is measured at the position of 680nm of a spectrophotometer. According to the technical scheme of the method, the design is reasonable, the relative standard deviation is less than 12%, and the recovery rate of standard addition reaches up to 96-99%; compared with the standard sample reference value, the method has the advantages that the analysis data is basically identical, the results are stable and accurate, simplicity and convenience are realized, and the operability is high.

The invention discloses a single molecular detection method of let-7a in human lung cells. The single molecular detection method comprises the following steps: (1) assembling a DNA (Deoxyribose Nucleic Acid) tetrahedral probe to obtain a DNA tetrahedral solution; (2) preparing a silanization glass substrate, then adding the DNA tetrahedral solution to the substrate, and inoculating to obtain a DNA tetrahedral substrate; (3) carrying out single molecular detection on let-7a, namely, detecting by adopting a standard addition method, firstly respectively adding materials to be detected to a Tris-HCl solution of standard let-7a with stagewise concentration to prepare samples to be detected; then adding a biotinylated ssDNA probe and a streptavidin quantum dot, imaging by using a fluorescent shooting microscope, respectively checking the number of phosphor dots, making a standard curvilinear equation, and calculating the concentration of let-7a. Experimental results prove that the single molecular detection method shows good specificity and sensitivity for miRNA (let-7a), and the limit of detection is 5fM.

The invention discloses a method for testing tin content of a tin-lead solder through a flame atomic absorption spectroscopy method. According to the method, nitric acid, hydrofluoric acid and hydrogen peroxide are used as solvents to rapidly decompose the tin-lead solder, the ratio of the nitric acid to the hydrofluoric acid to the hydrogen peroxide is 1:2:1, a sample is heated and dissolved by an electric heating plate at the low temperature, the absorbancy of the tin in a decomposition solution is measured by using the air-acetylene fuel-lean flame atomic absorption spectroscopy method, and the tin content in the decomposition solution is calculated by using a standard addition method. The method is high in testing accuracy and relatively small in error, the whole analysis test process is simple in operation, the amount of acid used is small, and the method is capable of rapidly analyzing the tin content of the tin-lead solder.

The invention discloses a determination method of the content of endogenous hormones in terminal buds of tomato plants. The method comprises the following steps: 1) preprocessing a tomato terminal bud sample for test; 2) preparing a mobile phase and setting chromatographic conditions; 3) preparing a standard liquid; 4) inspecting specificity; 5) inspecting a linear relation; and 6) determining sample content. The method of the step 1) comprises process of performing vacuum evaporation after extraction and petroleum ether extraction, further regulating pH, carrying out ethyl acetate extraction, and finally performing secondary vacuum evaporation to obtain a to-be-determined sample liquid; and in the step 2), the mobile phase is prepared from methanol and 0.075% glacial acetic acid. The determination method of the content of endogenous hormones in terminal buds of tomatoes by HPLC, provided by the invention, can quickly, accurately and simultaneously determine the content of four plant endogenous hormones, and has the characteristics of fast and efficient determination, high sensitivity and high degree of automation; a recovery of standard addition experiment is carried out, the average recovery is 99.85%, and RSD (Relative Standard Deviation) is less than 1.56%, which meets the hormone determination requirement.

The invention discloses a sample pretreatment method for determining the content of chloride ions and sulfate radicals in limestone solid, which comprises grinding a limestone sample, sieving with a 110 mesh sieve, and sealing in a sample flask; accurately weighing the limestone sample, adding a certain concentration of an acid solution for dissolving the sample to ensure the chloride ions and sulfate radicals to be fully released into the solution, and diluting to a constant volume; and neutralizing the sample solution with a certain concentration of alkali to regulate a pH value to a certain range, performing membrane filtration, and determining the content of chloride ions and sulfate radicals in the sample by ion chromatography. The method has simple process, easy operation, good repeatability, relative standard deviation smaller than 1.68%, and recovery of standard addition above 94.1%.

The invention belongs to the technical field of radioactive substance processing methods, and particularly relates to a method for analyzing fluorine ion concentration under a radioactive condition. The method is characterized in that a fluorine ion selective electrode method is adopted, by using sulfosalicylic acid-trisodium citrate as a total ion strength regulation buffer solution, the calculation is carried out by using a secondary standard addition method under a condition that pH is 8-9 so as to obtain F-concentration in an original sample. Aiming at the sample containing BF<4><->, the method provided by the invention has the advantages that complexing action on the ion F by the ion Al is skillfully utilized to ensure that BF<4><-> is completely hydrolyzed; in an analyzing process, distillation operation is avoided, and the loss of radioactive substances is reduced; moreover, a value of a slope S is not needed, and therefore, the errors caused by improper setting of the slope S can be avoided.

The invention discloses an inductively coupled plasma mass spectrometry used for determining trace aluminum molybdenum vanadium titanium niobium in silicon steel, and simultaneous determination of trace aluminum, molybdenum, vanadium, titanium, and niobium in silicon steel via inductively coupled plasma mass spectrometry (ICP-MS) is discussed. Determination parameters are optimized via condition experiments, and it is determined that RF power is 1400W, pump speed is 30rpm, sampling depth is 140, and atomization pressure is 0.90. Sample decomposition is realized using nitric acid, Be and Y mixed inner standard method is used for correcting signal drift caused by high matrix in measuring processes. Isotope 27Al, 98Mo, 51V, 47Ti, and 93Nb are taken as measuring isotopes based on mass spectrum interference conditions in determination; and at the same time, yield of double charged ions and oxide ions is adjusted to be lowest by adjusting instrument parameters so as to reduce influences. Calibration solutions are prepared via matrix matching, working curve is established via standard addition method, and reagent blank is deducted. Determination lower limit of the elements reaches 1<mu>g/g, and element RSD is less than 5.2% when the inductively coupled plasma mass spectrometry is used for determining silicon steel standard samples.