38results about How to "Low blank value" patented technology

A method for detecting cadmium content in cigarette used tipping paper is characterized in that the method can quickly and accurately detect the cadmium content in the cigarette used tipping paper by the following steps: adopting mixed acid to carry out microwave digestion for a sample, removing the acid and fixing volume, conducting detection with a graphite furnace atomic absorption spectrophotometer, etc. The method overcomes the shortcoming of the prior art in processing the sample. Compared with the traditional electric heating plate digestion manner, the microwave digestion manner can reduce the usage of samples and strong acid, improve digestion ability, cause less loss to elements to be detected in the sample and less damage to an operator, and facilitate operation. The digestion system of compound acid is completely applicable to the special material of the cigarette used tipping paper. The acid removing process is quick and easy, and a matrix modifier is adopted to eliminate interference. After being detected by optimal heating up programs, ashing temperature and atomization temperature related to atomic absorption spectrometry, the special material of the cigarette used tipping paper is recovered with high rate, and detected with accurate result. The working efficiency and the economic benefits are significantly improved.

A method for detecting the As in food, health-care food, or biological specimen includes dissolving the specimen in nitric acid and hydrogenperoxide mixture under action of microwave, adding the mixed solution of 150 g/L thiourea and 100g/L VC, mixing, taking 25ml solution laying aside at orinary temp for 40-50 min, and atomic spectrofluorimetry. Its advantages are high speed, correctness and sensitivity.

The invention relates to a method for testing the content of mercury in tipping paper for cigarette, which comprises using 3% hydrochloric acid to do constant volume to a certain volume after a tipper paper sample for cigarette is digested by mixed acid, utilizing sodium borohydride which contains sodium hydroxide to be reducing agent in the environment of strong acid-hydrochloric acid, deacidizing mercury in an ionic condition to elemental mercury, utilizing argon gas to be a carrier, and blowing vapor with mercury atoms under normal temperature in a cold atomic absorption spectrometry instrument to measure. Mercury atoms have a strong absorption function to a resonance line whose wavelength is 253.7nm, and the relationship between the size of absorption and the concentration of mercury atoms is in accordance with the beer law in a certain concentration scope, and the mercury atoms are compared with standard series to do constant volume. The method overcomes the shortcomings of the sample handling method in the prior art, which optimizes the concentration of acid, sodium borohydride and sodium hydroxide and the flow of carrier gas (argon gas) in a flow-injection cold atomic absorption spectrometry instrument. The invention has the advantages of simple operation, quick speed, accuracy, excellent sensitivity and repeatability.

The invention discloses a pretreatment method for determining multiple heavy metal elements in soil simultaneously. The pretreatment method comprises steps as follows: step (1): sample weighing: the soil is air-dried, ground and screened with a nylon sieve, a soil sample is weighed and put into a microwave digestion tube through a polytetrafluoroethylene long-neck funnel, and the funnel is slightly flapped before the funnel is removed so that all the soil sample attached to the wall of the funnel enter the digestion tube; step (2): digestion: nitric acid, hydrochloric acid and hydrofluoric acid are added to the digestion tube, a cover is screwed down, and the digestion tube is put into a microwave digestion instrument for digestion; step (3): acid driving: after microwave digestion is finished, hydrogen peroxide is added to the digestion tube; then the microwave digestion tube is put into a temperature-controlling acid driver in a fume cupboard for direct acid driving until the volume is smaller than 1 mL, then a solution is directly transferred to a volumetric flask, the volume is constant, and a to-be-tested solution is obtained. With the adoption of the pretreatment method, the digestion speed of the sample can be increased, the pre-treatment step of the sample is simplified, and the accuracy of the detection analysis result is guaranteed.

A magnetic signal measuring apparatus includes a first magnetic field applying unit that applies a first magnetic field to magnetic substances when a measured substance is binding to the magnetic substances, a second magnetic field applying unit that applies a second magnetic field to the magnetic substances to which the first magnetic field has been applied, and a SQUID that measures a magnetic signal derived from the magnetic substances. The first magnetic field has an intensity of such a degree that the magnetic substances do not flocculate with each other and such a degree that directions of magnetic moments in the magnetic substances can be aligned with each other. The second magnetic field has an intensity of such a degree that the magnetic substances do not flocculate with each other and such a degree that a magnetic signal can be obtained from the magnetic substances.

The invention discloses a sampling membrane and a sampler capable of enriching heavy metals in ambient air and an application method of the sampler. The sampling membrane comprises a nanometer fiber membrane and an air-permeable supporting padding arranged below the nanometer fiber membrane. The sampler comprises the sampling membrane and a sampling clamp; the sampling clamp is composed of an upper cone and a lower cylinder, wherein the upper surface of the cone is horizontal, the cylinder is composed of an upper cylinder and a rotary lower cylinder, the side surfaces of the upper cylinder and the lower cylinder are provided with uniformly distributed vertical ridges, the vertical ridges on the upper cylinder and the lower cylinder are aligned by rotating the lower cylinder, so fixation of the sampling membrane on the horizontal surface of the sampling clamp is realized. After heavy metals in air are acquired by using the sampler, a filter membrane is taken out and put into a centrifuge tube filled with a buffer solution, a solution is used for desorption of the heavy metals on the filter membrane, and after desorption, the solution is determined. According to the invention, detection sensitivity can be substantially improved, pre-treatment of a sample is easy and feasible, and nanometer fiber filter membranes with different functions are used for different detection objects, thereby improving absorption and acquisition efficiency.

A method for detecting cadmium content in cigarette used tipping paper is characterized in that the method can quickly and accurately detect the nickel content in the cigarette used tipping paper by the following steps: adopting mixed acid to carry out microwave digestion for a sample, removing the acid and fixing volume, conducting detection with a graphite furnace atomic absorption spectrophotometer, etc. The method overcomes the shortcoming of the prior art in processing the sample. Compared with the traditional electric heating plate digestion manner, the microwave digestion manner can reduce the usage of the samples and strong acid, improve digestion ability, cause less loss to elements to be detected in the sample and less damage to an operator, and facilitate operation. The digestion system of compound acid is completely applicable to the special material of the cigarette used tipping paper. The acid removing process is quick and easy. After being detected by optimal heating up programs, ashing temperature and atomization temperature related to atomic absorption spectrometry, the special material of the cigarette used tipping paper is recovered with high rate, and detected with accurate result. The working efficiency and the economic benefits are significantly improved.

The invention provides a method for determining volatile phenol in water. In color reaction using 4-amino-antipyrine direct spectrophotometry to determine volatile phenol in water, the method uses Tween-80 as nonionic surfactant to play a role in stability augmentation and sensitivity enhancement, reduce system blank value and improve determination sensitivity. The method comprises the following steps: accurately shifting 1.00 mu g/mL of freshly prepared phenol-standard solution or a certain amount of to-be-determined water sample subjected to predistillation into a 50mL colorimetric tube; adding water to a scale; adding 0.50 mL of ammoniacal buffer solution and fully mixing the materials; adding 0.40 mL of 1 percent Tween-80 solution and mixing the materials well; adding 1.50 mL of 2 percent 4-amino-antipyrine solution and fully mixing the materials for 2 minutes; adding 1.00 mL of 8 percent potassium ferricyanide solution, fully mixing the materials for 1 minute and keeping the mixture stand for 10 minutes; and then determining the absorbance value of the mixture. A colored compound solution prepared in the invention is stable for at least 2 hours, thus the stability of the colored compound solution is greatly enhanced than that in the prior method before improvement, and the colored compound solution is obviously lower in blank absorbance value and higher in sensitivity, and has detection limit lower than that of the national standard method. The method has the advantage of determining the volatile phenol in tap water samples, along with high recovery rate and accurate results.

The implementation mode in the invention provides a purity detecting method and a device for polysilicon, which belongs to the fields of chemical industry and solar energy. The method comprises the following steps: after evenly mixing silicon powder, washing with secondary deionized water, and drying to constant weight; putting the dried silicon powder on a Teflon tray, adding water to moisturizethe sample, and adding a polyol solution; putting the Teflon tray on a Teflon container, putting the Teflon container in a seal body, adding HF and HNO3 into the lower part of the seal body, sealing the seal body, and heating to 110-120 DEG C; and after the silicon powder is completely dissolved and volatilized to the dry state, adding HNO3 to dissolve residues, transferring to a plastic volumetric flask, and measuring the content of impurity elements after the volume becomes constant. The specific implementation mode in the invention also provides a special device for realizing the purity detecting method for polysilicon. The method and the device have the advantage of high detection accuracy.

A method for determination of calcium in a sample derived from a living body, by the reaction of calcium in the sample with Chlorophosphonazo-III or a compound analogous thereto in the presence of vanadate ions, followed by determination of calcium in the sample on the basis of an optical change caused by the reaction product, is excellent in various respects as follows: it is free from the problem of absorption of carbonic acid gas caused by a high pH; it is free from the problem of use of a toxic reagent containing arsenic; it makes it possible to subject a large number of samples to determination in a short time because it can be applied to an autoanalyzer; and it permits determination in a wide range because of low sample blank values.

The invention provides a method for measuring the content of free carbon in molybdenum carbide. The method comprises the following steps: (1) adding molybdenum carbide powder into nitro-hydrochloric acid and stirring to dissolve molybdenum carbide in nitro-hydrochloric acid and allowing free carbon to disperse in an undissolved state in nitro-hydrochloric acid, the mass and unit of the molybdenum carbide powder being m0 and g respectively; (2) performing first drying treatment on filter paper, the mass and unit of the filter paper subjected to first drying treatment being m1 and g respectively; the filter paper being binder-free glass fiber filter paper; (3) performing filtration treatment on nitro-hydrochloric acid using filter paper, performing secondary drying treatment after washing with deionized water, and the mass and unit of the filter paper subjected to secondary drying treatment being m2 and g; (4) calculating the mass percentage content x of free carbon in the molybdenum carbide powder. The content of free carbon is detected and analyzed using nitro-hydrochloric acid and binder-free glass fiber filter paper. The design is reasonable, the operation is convenient and easy, the detection error is less, and the result accuracy is high.

The invention discloses a method for leaching and measuring molybdenum metal in a nickel-molybdenum ore. The nickel-molybdenum ore is treated by a roasting-alkaline leaching method, and a three-factor and three-level test is executed by an L9(43) orthogonal design, so that extraction conditions for the molybdenum content of the nickel-molybdenum ore are optimized; leaching liquid under optimal conditions is centrifugally filtered and then is diluted and quantified; the content of molybdenum is measured by an atomic emission spectrometer; a result shows that the following factors which affect the extraction rate of the molybdenum content of the nickel-molybdenum ore mainly comprise the concentration of sodium hydroxide, the roasting time and the roasting temperature in sequence; under the optimal conditions of leaching molybdenum through sodium hydroxide, the roasting time is 2.5h, the roasting temperature is 500 DEG C, and the concentration of sodium hydroxide is 40 percent. Under the same atomic emission spectroscopy optimized conditions, a marking recycling experiment is performed on a sample. The recycling rate of elements measured by the method is 97.2-102.3 percent, so that the method is high in accuracy. The relative standard deflection is 0.92-1.24 percent, so that the method is high in precision. Therefore, the method can be used for reliably analyzing the molybdenum content of the nickel-molybdenum ore.

The invention relates to a safe and efficient method for determining aluminum in food, which comprises the following steps: (1) weighing a proper amount of sample, and carbonizing by using a resistance furnace; (2) placing the carbonized sample in a muffle furnace for ashing; and (3) taking out the ash, cooling, dissolving with 1% sulfuric acid, and transferring into a 50mL colorimetric tube to obtain a to-be-detected solution. According to the safe and efficient method for determining aluminum in food, no reagent is added basically, so that the blank value is low; the ash content volume of most food after burning is small, so that more samples can be treated, detected components can be enriched, and the detection limit is reduced; organic matters are thoroughly decomposed and the operation is simple.

The invention relates to a method for measuring the volume hydrogen content in high-purity aluminum or high-purity aluminum alloy. The method comprises the following steps: dividing a to-be-measured sample of the high-purity aluminum or high-purity aluminum alloy into a to-be-measured sample A and a to-be-measured sample B; putting the treated to-be-measured sample A into a hydrogen determinator for surface hydrogen determination, and putting the treated to-be-measured sample B into the hydrogen determinator for surface hydrogen and volume hydrogen determination; and finally, subtracting the measurement result of the to-be-measured sample B from the measurement result of the to-be-measured sample A to obtain the volume hydrogen content in the to-be-measured sample of the high-purity aluminum or high-purity aluminum alloy. According to the method, aiming at the interference problem of surface hydrogen, the sample to be detected is divided into two parts, and the two parts are separatelydetected and subtracted, so that the volume hydrogen can be deducted, the blank values from carrier gas, instruments and crucibles can be reduced, and the content of the volume hydrogen in high-purity aluminum or high-purity aluminum alloy can be accurately determined.

The invention relates to a method for detecting elemental phosphorus content in industrial wastewater. The method for detecting the elemental phosphorus content in the industrial wastewater comprisesthe steps that the industrial wastewater containing elemental phosphorus is extracted with an organic solvent (benzene), and the elemental phosphorus is collected in extract liquor (benzene); and an appropriate amount of the extract liquor is sucked, a fixed amount of anhydrous methanol and a small amount of silver nitrate are added, the precipitated silver is evenly distributed in a benzene-methanol-water system, and the elemental phosphorus content in the wastewater is determined by spectrophotometer colorimetry. A extraction-spectrophotometry method is adopted to determine the elemental phosphorus content in the industrial wastewater, and the method for detecting the elemental phosphorus content in the industrial wastewater is simple to operate and relatively short in time; a spectrophotometer is used for detecting, a blank value is small, and the detection accuracy can reach 0.01 ppm, so that the method for detecting the elemental phosphorus content in the industrial wastewater ismore conducive to measuring the low-content element phosphorus. An adding standard recovery experiment verifies that the recovery rate is 97% or above, and the experimental result is accurate and reliable.