1145 results about "Relative standard deviation" patented technology

The invention discloses hot pepper and a determining method for 96 pesticide residues in a product of the hot pepper. The determining method comprises the following steps: homogenously extracting residual pesticide in a sample with 1% acetic acid-acetonitrile solution, purifying the extracting solution with a Florisil solid phase extraction column, dispersing and purifying the extracting solution with ethylenediamine-N-propyl silane (PSA) and octadecyl silane bonded phase (C18) substrate, detecting 69 pesticide residuals in the purified concentrated liquid of the Florisil column by GC-MS (gaschromatographic mass spectrometry), detecting 27 pesticide residuals in the substrate dispersed purified liquid by liquid chromatography-tandem mass spectrometry (LC-MS / MS), using the black substrate solution dilution standard to construct the updated calibration curves, adopting an internal standard method to quantify when using GC / MS to detect the residuals, and adopting an external standard method to quantify when using LC-MS / MS to detect the residuals. The average recovery rate of the method is 70.7-118.6%; the average relative standard deviation (RSD) is 3.2-11.4%; the detection limit is 0.13-28.2 ug / kg. The determining method has the advantages of simplicity and convenience in operation, high speed, accuracy, high sensitivity and good repeatability.

The invention provides a method for simultaneously determining one hundred pesticide residuals in a traditional Chinese medicine through ultrahigh performance liquid chromatography-tandem quadrupole mass spectrum. The method comprises the following steps: immersing traditional Chinese medicine powder with ultrapure water, extracting with acetonitrile containing 0.1% acetic acid through a homogenate method, carrying out solid phase dispersing purification with N-propylethylenediamine and graphitized carbon, detecting in a timesharing multi-reaction monitoring mode through the ultrahigh performance liquid chromatography-tandem quadrupole mass spectrum, and quantifying with an external standard curve method. 88% of pesticides have good linear relations in a range of 5-500ng / mL, correlation coefficients are above 0.99, and the correlation coefficients of above 98% of the pesticides are above 0.97; the average recovery rate of the pesticides with the low concentration of 10mug / kg, the middle concentration of 50mug / kg and the high concentration of 100mug / kg is 70-130%, and the relative standard deviation is less than 0.15; and the detection limit is equal to or less than 0.01mg / kg, so routine detection requirements can be completely satisfied. The method has the advantages of strong versatility, good selectivity, high sensitivity, and rapidness and simplicity.

Droplets or plugs within multiphase microfluidic systems have rapidly gained interest as a way to manipulate samples and chemical reactions on the femtoliter to microliter scale. Chemical analysis of the plugs remains a challenge. It has been discovered that nanoliter plugs of sample separated by air or oil can be analyzed by electrospray ionization mass spectrometry when pumped directly into a fused silica nanospray emitter nozzle. Using leu-enkephalin in methanol and 1% acetic acid in water (50:50 v:v) as a model sample, we found carry-over between plugs was <0.1% and relative standard deviation of signal for a series of plugs was 3%. Detection limits were 1 nM. Sample analysis rates of 0.8 Hz were achieved by pumping 13 nL samples separated by 3 mm long air gaps in a 75 μm inner diameter tube. Analysis rates were limited by the scan time of the ion trap mass spectrometer. The system provides a robust, rapid, and information-rich method for chemical analysis of sample in segmented flow systems.

A unit dosage form comprising atorvastatin or a pharmaceutically acceptable salt thereof, prepared without a granulation step, wherein the measured atorvastatin potency of said dosage form shows a relative standard deviation (RSD) for atorvastatin potency per unit dosage form of not more than about 7.8%, when said unit dosage form is prepared at a rate that greater than 10,000 unit dosage forms per hour per single unit dosage form per machine, as well as the unit dsoage form in combination with at least one active drug, methods for preparing unit dosage form, kits for containing such compositions and a method of treating hypercholesterolemia and / or hyperlipidemia, osteoporosis, benign prostatic hyperplasia (BPH), and Alzheimer's Disease using a therapeutically effective amount of the unit dosage form.

The invention discloses an analysis method for simultaneously measuring residues of 12 sulfonamide medicaments, 19 quinolone medicaments and 8 benzimidazole medicaments and metabolites thereof in chicken liver by quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction and purification-ultrahigh performance liquid chromatography-tandem mass spectrometry (QuEChERS-UPLC-MS / MS). The method comprises the following steps of: extracting a sample by using 1 percent acetic acid-acetonitrile solution, purifying the sample by using NH2 adsorbent, and degreasing the sample by using n-hexane;and then performing separation by using a Kromasil Eternity C18 chromatographic column (100mm*2.1mm, 2.5mum), performing gradient elution by using 0.1 percent formic acid and methanol as mobile phases, performing ionization in an electron spray positive ion (ESI<+>) mode, performing detection in a multi-reaction monitoring (MRM) mode, and performing quantification by an internal standard method. The 39 medicaments have good linearity (r is more than 0.98) in a blank adding concentration range of 5 to 100mug / kg, the average recovery rate of the medicaments in the adding level range of 10 to 50mug / kg, the relative standard deviation (RSD) is 1.5 to 23.4 percent, the limit of detection (LOD) of the 39 medicaments is 5mug / kg, and the low limit of quantification (LOQ) is 10mug / kg. The method is simple, convenient, quick, sensitive, accurate and rugged, and is suitable for confirmation and quantitative determination of the residues of the residues of the sulfonamide, quinolone and benzimidazole medicaments in the chicken liver.

The invention discloses an analysis method for simultaneously determining 16 phenolic compounds in water environment, and belongs to the technical field of phenolic compound analysis. According to the invention, solid phase extraction (SPE) is used for preprocessing a water sample, and a gas chromatography and mass spectrum coupling technique method (GC-MS) is used for qualitatively and quantitatively analyzing the 16 phenolic compounds in the water sample. Under the analysis condition optimized by the analysis method, the 16 phenolic compounds in water can be simultaneously determined, a good chromatographic peak can be obtained within 28 minutes, and a good separation effect can be obtained. The linearity of all the objective compounds in the concentration range of 5-1000 <mu>g / L is good, the correlation coefficients are all more than 0.9959, the detection limit achieves 0.04-4.0 <mu>g / L, the relative standard deviation is 0.22-13%, and the labeling recovery rate is 77-112%. The analysis method disclosed by the invention is simple, easy to operate, accurate and reliable, so that the analysis method is suitable for detecting large-scale samples.

The invention discloses a method that can simultaneously analyze various elements, aims at solving the defects that currently the analysis of various elements cannot be finished at one time, and consequently the analysis time is long and the reagent usage is large, and discloses a method that can simultaneously measure the elements of silicon, aluminum, calcium and barium and comprises the following steps: a test sample is preprocessed through the acid dissolution method, microwave-digested, naturally cooled, and then placed into a volumetric flask with scales, diluted and shaken until well distributed, a solution with a standard working curve is prepared, an atomic emission spectrograph of inductance coupled plasmas is started and led to reach the measurement requirement, a plasma torch is lighted, the relative standard deviation of the plasma torch is led to be less than 5 percent, wavelength of each element is chosen, the working curves are plotted, and the content of each element is computed. The method combines the microwave digesting sample dissolution technique with the atomic emission spectrograph of inductance coupled plasmas, can simultaneously analyze nine elements including silicon, etc., is accurate and quick, has greatly reduced reagent usage, and reduces the environmental pollution that is caused by chemical reagents.

The invention relates to a quantitative detection method for thermal-denaturation and non-denaturation bovine alpha-lactalbumin in milk and milk products by applying an enzymolysis-liquid chromatography and mass spectrometry combination technology. The quantitative detection method comprises the steps as follows: taking a certain amount of milk or milk samples, dissolving and diluting the milk or milk samples in water to obtain solution with total protein content being about 1mg / mL; after volume metering, correctly sucking 500 mu L, adding an internal standard substance, reacting disulfide bond with dithiothreitol (DTT), alkylating to protect sulfydryl produced in reaction by iodoacetamide (IAA), and then conducting constant-temperature and constant-time enzymolysis with trypsin; and separating enzymolysis products by reversed phase liquid chromatography, conducting detection with a mass spectrum multiple reaction monitoring (MRM) manner, and calculating the result by an internal standard method. The quantitation limit of the method is 0.001g / 100g; when adding amount is 0.2, 1.7 and 5.0g / 100g, the recovery rate is 98.9-110.8% (n is equal to 6) and repeatability: RSD (Relative Standard Deviation) is smaller than 7.6%; and the quantitative detection method can be applicable to the quantitative detection of samples with different contents of bovine alpha-lactalbumin.

The invention provides a determination method of volatile organic acids in cigarette mainstream smoke. According to the determination method, the content of the volatile organic acids in total particulate matters of the cigarette mainstream smoke is determined by adopting vibration extraction and a gas chromatography-mass spectrometry technology. The determination method particularly comprises the following steps: (1) preparing a standard solution; (2) pretreating a sample; (3) qualitatively detecting the sample; (4) quantitatively detecting the sample; and (5) determining the content of the actual sample. According to the determination method of the volatile organic acids in the cigarette mainstream smoke, a standard sample addition method is used for qualifying and an internal sample standard curve method is used for quantifying; the recycling rate of the method is 97.5%-110.3%; the relative standard deviation (RSD%) of the method is 1.2%-8.5%; and the determination method has good sensitivity, accuracy and precision. Meanwhile, the method adopts the vibration extraction and a sample can be directly fed without deriving; and the determination method is simple and convenient to operate, and rapid in analyzing speed and is suitable for the determination of a large batch of the samples.

A method of image information enhancement in radiography relates to image information processing techniques in radiography. The method comprising steps of: normalizing an acquired image A(x,y) to form a normalized image B(x,y); filtering the normalized image B(x,y) by a low-pass filter to obtain an filtered image C(x,y); calculating a relative standard deviation for each pixel in the image A(x,y), three times the relative standard deviation being an edge threshold for each pixel; thresholding a difference image obtained by subtracting the filtered image C(x,y) from the normalized image B(x,y) by using the edge threshold for each pixel to form a threshold-processed image D(x,y); enhancing a contrast of the threshold-processed image D(x,y) by using a non-linear function to form a contrast-enhanced image E(x,y); determining a enhancement coefficient a(x,y); obtaining a edge-enhanced image F(x,y) by multiplying the enhancement coefficient a(x,y), the contrast-enhanced image E(x,y) and the filtered image C(x,y); and generating a resulting image by multiplying a sum of the edge-enhanced image F(x,y) and the filtered image C(x,y) with the maximum value Amax As compared with the prior arts, the inventive method has a fast processing speed for image information enhancement and a simple algorithm, images clearly, eliminates noises in the images, and satisfies the requirements of relatively more enhancement to the contrast of the dark regions in the scanned images.

The invention discloses a method for quickly detecting lead and cadmium by adopting scanning anodic stripping voltammetry. The method comprises the following steps: a sample to be tested is prepared; lead or cadmium standard liquid is prepared; a three-electrode system consisting of glassy carbon electrodes plated with mercury films, platinum wire counter electrodes and Ag / AgCl reference electrodes is assembled; parameters are set and the scanning anodic stripping voltammetry is adopted to respectively implement parallel determination for current values between working electrodes and reference electrodes of each standard liquid solution until the relative standard deviation of readings is not more than 5%; lead and cadmium heavy metals of the sample are measured through detecting the current values between the working electrodes and the reference electrodes; a working station automatically calculates to obtain detecting results through automatically searching peaks to determine each curve peak area. The detecting method has the advantages of high sensitivity, good accuracy, reduction of mercury pollution, high electrode stability and good reproducibility, and can be applied to the detection of the heavy metals of lead and cadmium with conventional trace and ultratrace.

This invention relates to a method for dyeing polymer microspheres to obtain fluorescent polymer microspheres. The method comprises: uniformly mixing fluorescein 0.01-80%, polymer microspheres 0.1-80%, emulsifier 0-10%, tackifier 0-10%, and solvent (one or more of good solvents and poor solvents) 18.9-99.89%, dyeing under 1-101 kPa in dark for 1-720 h, taking out the dyed polymer microspheres, and washing repeatedly. The obtained fluorescent polymer microspheres have such advantages as simple process, high fluorescent brightness, wide fluorescent spectrum range, uniform particle size distribution and low relative standard deviation, and can be used as absolute counting microspheres of flow cytometry, fluoroimmunoassay microspheres, biosensor, microfluidic chip, and calibrator of fluorescence microscope.

The invention discloses a common rapid detection method for various pesticide residues in soybeans. The common rapid detection method is characterized by particularly comprising the following steps: homogenizing and extracting a soybean sample by acetonitrile; carrying out salting-out and centrifuging to obtain a supernatant; purifying by using a solid phase extraction column to obtain a sampling solution; preparing a mixed standard solution and preparing a base material adding standard curve; simultaneously detecting 306 types of pesticide residues in the soybeans by a gas chromatography-tandem mass spectrometer; finally, calculating the concentration. The common rapid detection method has the advantages that the effect of the base material and background interferences are reduced and the anti-interference capability of the method is improved greatly; the analysis sensitivity is improved; the detection linear range is 0-0.2microgram / milliliter; the detection is limited to be 0.01mg / kg; the recycling rate is 60%-120%; the relative standard deviation RSD is less than or equal to 20%; the recycling rate is ideal and the precision degree is good; the common rapid detection method is simple and rapid, is low in background interferences, good in selectivity and high in sensitivity.

The invention discloses a method for simultaneous measurement of 17 trace elements in reconstituted tobacco by using inductively coupled plasma mass spectrometry. According to the invention, microwave digestion and inductively coupled plasma mass spectrometry are combined together to measure 17 trace elements in reconstituted tobacco; a reconstituted tobacco sample is subjected to microwave digestion, and then ICP-MS measurement is quantitatively carried out through combination of a standard mode, collision / reaction cell technology and an internal standard method. Measurement results show that: 17 target elements have good linearity, a correlation coefficient r is no less than 0.9995, a detection limit is 0.001 to 0.065 mu g / L, an added standard recovery rate is 79.31 to 123.07%, and relative standard deviation is 1.15 to 6.38%. The method provided by the invention has the advantages of simple operation, short analysis time, stability, accuracy, etc. and can be used for analysis and test of large-batch reconstituted tobacco samples in the tobacco industry.

The invention discloses a determination method of residual amount of glufosinate, glyphosate and aminomethyl phosphoric acid in food. The determination method of residual amount of glufosinate, glyphosate and aminomethyl phosphoric acid in food comprises the following steps: in the sample pretreatment, firstly, extracting glufosinate, glyphosate and aminomethyl phosphoric acid in a food sample by a methanol water solution in sample pretreatment; then purifying an extracting solution by selecting a C18 dispersive solid-phase extraction agent; and finally, filtering, deriving, and determining three compounds qualitatively and quantitatively synchronously by combining with high performance liquid chromatography-tandem mass spectrum. According to the method provided by the invention, the operation is simple and convenient, and the reproducibility is good, and impurities in a sample extraction solution can be removed effectively; the pretreatment is the supplement and improvement of the existing QuEChERS method; the recycling rate can reach 70.5%-91.2%; the relative standard deviation is 4.5%-7.83%; the limit of quantification is 50micro-g / kg; the determination method can completely meet the technical requirement on safety detection of China, European Union, America and Japan, and can provide powerful technical support for food safety and export trade healthy development for people of China.

Belonging to the technical field of soil and sediment pollution detection, the invention relates to a dispersive solid-phase extraction gas chromatography method for polychlorinated biphenyls (PCBs) in soil and sediment. The method includes: adding n-hexane into a soil or sediment sample to conduct ultrasonic extraction, when the extraction liquid is basically colorless and transparent, subjecting the extraction liquid to rotary evaporation till dry, adding n-hexane, then adding 50-200mg of a N-propylethylenediamine solid phase adsorption agent to carry out dispersive solid-phase extraction, performing centrifugal layering, and introducing 1microliter of the supernatant into a gas chromatography-electron capture detector to conduct detection, otherwise adding a concentrated sulfuric acid purification step after ultrasonic extraction. The detection limit of 7 polychlorinated biphenyls is 0.02-0.03 microgram / kg, the recovery rate is 72-115%, and the relative standard deviation (n=5) is 3.5-6.9%. The method provided by the invention is simple and sensitive, and can quickly realize batch detection of PCBs in soil and sediment.

The invention provides a method for measuring volatility phenol compound in white wine and belongs to the field of researching the white wine flavor. The method of the invention qualitatively and quantitatively analyzes the volatility phenol compound in white wine by combining the dipping solid phase micro-extraction technique (DI-SPEM) with gas chromatograph-mass spectrometer technique (GC-MS). The method of the invention can rapidly detect and accurately quantify the volatility phenol compound in the white wine by using the dipping solid phase micro-extraction technique without fussy pre-treating process. The method is rapid and simple. The accuracy of the result is promoted by using the gas chromatograph-mass spectrometer technique to detect the volatility phenol compound in the white wine. Seven phenol compounds in the measured scope have an excellent linear relationship that R2 is more than 0.99; the limit of the detection of the seven phenol compounds I is less than 7 ug / L; the relative standard deviation is less than 15%; the recovery rate is ranged between 85% and 115%. The invention provides a base for further researching the forming principle of the volatility phenol compound and has a significance to improve the quality of the white wine.

The invention discloses a method for determining ammonia nitrogen content in water through a Nessler reagent spectrophotometric method. The method comprises the following steps: (1) taking an original water sample to be analyzed; (2) performing pretreatment on the original water sample; (3) taking the water sample after pretreatment, loading into a colorimetric tube, shaking up, then adding a Nessler reagent into the colorimetric tube, further shaking up, placing for a certain period of time and adopting a spectrophotometer to test the absorbency of the water sample; (4) adopting distilled water to do a blank test to get blank absorbency; and (5) enabling the absorbency measured in the step (3) to deduct the blank absorbency measured in the step (4) to get correction absorbency, drawing a standard curve and calculating the ammonia nitrogen content in the water. The method has the benefits of fast determining the ammonia nitrogen content in the water, preventing suspended matters and residual chlorine from interfering with the detection result through the pretreatment of the original water sample, and effectively improving the accuracy of the detection result; and furthermore, the method is good in repeatability and less in relative standard deviation.

The invention relates to a process for analyzing gas-phase total components in a cigarette mainstream smoke through an airbag-thermal desorption-gas chromatography / mass spectrometry method. The process allows an airbag, an adsorption sampling tube, a syringe pump and a thermal desorber-gas chromatograph / mass spectrometer, utilizes the airbag to collect a cigarette mainstream smoke, allows the smoke in the airbag to be adsorbed to the adsorption sampling tube through the syringe pump, and utilizes the thermal desorber-gas chromatograph / mass spectrometer to desorb, age, detect and qualitatively and quantitatively analyze, so the advantages of each of above instruments are used, the repeatability is improved, the relative standard deviations of most measured substances in the gas-phase full components are below 5%, and the repeatability is substantially better than the previously-reported repeatability.

The invention relates to a detection method of vitamin in food, in particular to a method for detecting biotin content in the food by using ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometer. The method comprises a sample pre-treatment method, ultra-high performance liquid chromatography detection, and tandem mass spectrometric detection step, and comprises the following steps: separating by using HSS T3 liquid chromatographic column, performing gradient eluting by using 10mmol / L ammonium acetate buffer solution (containing 0.1% formic acid) and acetonitrile as mobile phases, and performing qualitative and quantitative analysis by using electron spray-positive ion ionization source multi-reaction monitoring mode. The result is that the method quantitation limit of the biotin (VB7) is 0.6 microgram / 100g, the recovery rate is 81.3%, relative standard deviation is 5.5%, and the linear range is 0.2-10ng / mL. The method is simple in analysis operation, fast, high in sensitivity, good in repeatability, and suitable for quantitatively detecting the biotin in milk powder.

A method of image information enhancement in radiography relates to image information processing techniques in radiography. The method comprising steps of: normalizing an acquired image A(x,y) to form a normalized image B(x,y); filtering the normalized image B(x,y) by a low-pass filter to obtain an filtered image C(x,y); calculating a relative standard deviation for each pixel in the image A(x,y), three times the relative standard deviation being an edge threshold for each pixel; thresholding a difference image obtained by subtracting the filtered image C(x,y) from the normalized image B(x,y) by using the edge threshold for each pixel to form a threshold-processed image D(x,y); enhancing a contrast of the threshold-processed image D(x,y) by using a non-linear function to form a contrast-enhanced image E(x,y); determining a enhancement coefficient a(x,y); obtaining a edge-enhanced image F(x,y) by multiplying the enhancement coefficient a(x,y), the contrast-enhanced image E(x,y) and the filtered image C(x,y); and generating a resulting image by multiplying a sum of the edge-enhanced image F(x,y) and the filtered image C(x,y) with the maximum value Amax As compared with the prior arts, the inventive method has a fast processing speed for image information enhancement and a simple algorithm, images clearly, eliminates noises in the images, and satisfies the requirements of relatively more enhancement to the contrast of the dark regions in the scanned images.

The invention discloses an automatic calibration method of a water quality monitoring system with adoption of an ultraviolet absorption method. The automatic calibration method is characterized in that a standard solution colorimetric cuvette switching device is designed and installed on a measurement optical path so that multipoint calibration can be performed within the measuring range of the system, and corresponding algorithms are adopted in a processor to determine a coefficient of correction in order to realize automatic calibration. The method has the advantage of saving a large amount of manual operation, improving the accuracy and practicability of the system and providing technical support for long-term online monitoring of water pollution. In a standard solution comparison experiment, the relative standard deviation is not more than 1% and the maximum relative error is not more than 2%, thus relevant national standards are accorded with.

This invention relates to one method to test pyrazine compound in alcohol in liquor taste study, which applies top fix phase micro extraction and gas phase spectrum and flame thermal ion test device and uses gas phase spectrum and flare thermal ion test device cross technique in liquor with strong abnormal property of compound with good linear relation for R2>0.99 and compound test limit less than 1 mu g / L; Repeating the test relative standard bias for less than 15 percent and recycle rate larger than 80 percent.

The invention discloses a method for quantificationally detecting phenolic compounds in solid-state fermentation products and belongs to the technical field of analysis of solid-state fermentation products. The method is mainly suitable for determination of the content of phenolic compounds in solid-state fermentation products of liquor, wherein the phenolic compounds includes yeast for preparing hard liquor, fermented grains and cellar mud. The invention particularly relates to ultrasonic extraction, headspace solid-state-phase micro-extraction and gas chromatography-mass spectrogram combined qualitative and quantitative analysis of solid-state fermentation products. The method built by the invention can be used for quickly detecting 10 kinds of volatile phenolic compounds in the solid-state fermentation products; the phenolic compounds have a favorable linear relationship R2 is more than 0.99 within a detection range; all detection limits are less than 10microgramme / L; the relative standard deviation is less than 10%; and the recovery rate is 75%-110%. The technical scheme provided by the invention is simple, convenient and quick, can be used for achieving effective monitoring of the volatile phenolic compounds in the solid-state fermentation products, and has the great significance in improving the quality of final products.

The invention discloses a method for rapidly measuring ethyl carbamate content in distilled liquor, belonging to the technical field of analysis measurement. In the invention, the impurities are removed by adopting rotary evaporation, the ethyl carbamate in a liquor sample is enriched by adopting headspace-solid phase microextraction technology, then gas chromatography-mass spectrum technology is adopted for conducting quantitative measurement, and the EC content in the liquor sample is calculated according to a standard curve. According to the method established in the invention, the ethyl carbamate in the distilled liquor can be detected rapidly and quantified accurately, the detection limit can be lowered to be 1.16mug / L, the linear correlation coefficient is more than 0.99, the recovery rate is 89%-119%, and the relative standard deviation is 1.26%-12.51%. In the method, a plurality of defects of in the original measuring method is overcome, the complicated pretreatment process and organic solvent are not needed, and the method is used for detection and quantitative analysis on the ethyl carbamate in the various distilled liquor with higher alcoholic strength.

This invention relates to one method to test sulfur compound in the analysis technique, which uses top fix phase micro extraction and gas phase and color spectrum and impulse flare light tester cross technique for quantitative analysis. This invention establishes one sulfur compound test with rapid speed with limit to 0.01 mu g / L, linear relative parameter R2 less than 0.98 and with relative standard error less than 20 percent and alcohol recycle rate as 80 to 100 percent.

The invention discloses a spectrophotometric method for determining the ammonia nitrogen content in water. The method comprises the steps that: (1) an original water sample requiring analyzing is fetched; (2) pre-treatment of the original water sample is carried out, wherein residual chlorine is removed, suspended solids are removed by filtration, and a masking agent which is potassium sodium tartrate is added for eliminating the interference of magnesium ions; (3) the absorbance of the water sample is tested by using a spectrophotometer; (4) a blank test is carried out by using distilled water, such that a blank absorbance is obtained; and (5) the blank absorbance obtained in the steps (4) is subtracted from the absorbance obtained in the step (3), such that a corrected absorbance is obtained; a standard curve is drawn, and the ammonia nitrogen content in water is calculated. The method provided by the invention is advantaged in that: with the method provided by the invention, the ammonia nitrogen content in water can be rapidly and conveniently tested. Through the pre-treatment upon the original water sample, interferences of the suspended solids, the residual chlorine, the calcium ions and the magnesium ions upon testing results can be avoided, and the accuracy of testing results can be effectively improved. The method is also advantaged in good repeatability and low relative standard partial.

The invention belongs to the field of pharmaceutic preparations, and particularly provides a pramipexole dihydrochloride slow-release tablet with high content uniformity and a preparation method thereof. The invention provides the pramipexole dihydrochloride slow-release tablet which is independent of pH (potential of hydrogen) during drug release, is slowly released in buffer solutions with pHs of 1.2, 4.5 and 6.8 for 24 hours, reaches final release amounts above 85 percent without exception and only needs to be taken once every day. The preparation method provided by the invention is simple and practicable, relative standard deviations (RSDs) of the content uniformity and the release rate of the low-dose medicine, namely the pramipexole dihydrochloride can be guaranteed to be far below the RSD in a limit requirement, the between difference is small and the repeatability is high.

The invention discloses a method for quickly determining ethyl carbamate (EC) in alcoholic drink, which comprises the following steps of: diluting an alcoholic drink sample to be tested into the alcoholic drink sample with final alcoholic content of 4 percent to 20 percent (v / v) by double distilled deionized water; concentrating EC in the alcoholic drink sample through a head space solid-phase micro-extraction technology without a complex preprocessing process or organic solvent; carrying out detection and quantification analysis through a gas chromatography-mass spectrometer technology; and comparing with a standard curve to calculate the content of EC in the alcoholic drink sample. The method disclosed by the invention can be used for quickly testing and determining the EC in the alcoholic drink, the detection limit can reach as low as 1.19 mug / L, the linear correlation coefficient is larger than 0.99, the recovery rate is 90.21 percent to 99.07 percent, and the relative standard deviation is less than 10 percent. The method overcomes defects of the prior determining method, and can be used for detection and quantification analysis of the EC in the alcoholic drink.

The invention discloses a monazite 10-micron small-beam-spot LA-Q-ICP-MS U-Th-Pb age determination method. The method includes the steps that a standard solution sample with the concentration of 1 ppb is directly led into a four-level-rod inductively coupled plasma mass spectrometer, the instrument parameters are optimized, the response strength of <205>T1 is larger than 200,000 cps / ppb, the relative standard deviation is 1% to 2%, the double charges are smaller than 1.5%, and the yield of oxidation is smaller than 1%; an artificial glass NTSI 610 solid standard sample is led into the four-level-rod inductively coupled plasma mass spectrometer in a laser ablation mode, carrier gas of a laser and carrier gas of the four-level-rod inductively coupled plasma mass spectrometer are matched, and counting of <238>U reaches the maximum; a monazite standard sample 44069 is led into the four-level-rod inductively coupled plasma mass spectrometer in a laser ablation mode, the density of laser energy is 3 J / cm<2>, the impulse frequency is 4 Hz, and the age of monazite U-Th-Pb is determined through a 10-micron small laser beam spot. By means of the method, the space resolution ratio of monazite LA-Q-ICP-MS U-Th-Pb age determination is increased, and the testing requirement of monazite is met.