78results about How to "High spike recovery" patented technology

The invention discloses a method for measuring total nitrogen content in environmental water by adopting ultraviolet spectrophotometry. The method comprises the following steps: (1) sampling, that is, collecting environmental water to be detected; (2) preparing a reagent to be used, namely an alkaline potassium persulfate solution; (3) processing a water sample, that is, adding the alkaline potassium persulfate solution into the environmental water to be detected, then placing the water sample in a digester of 128 DEG C for digestion, reducing the obtained nitrate into nitrite through a cadmium column, adding a hydrochloric acid solution into the nitrite and uniformly fixing; (4) testing, that is, taking non-ammonia water as the reference and adopting an ultraviolet spectrophotometer to detect the absorbency; (5) achieving blank sample correction; and (6) calculating the total nitrogen content in the environmental water. The invention has the benefits that defects in the prior art are avoided; the method for measuring total nitrogen content in environmental water by adopting ultraviolet spectrophotometry, provided by the invention, is simple, and has high measurement accuracy; and samples detected by adopting the method has high recovery rate, and the RSD (Relative Standard Deviation) is small.

The invention provides a method for rapidly measuring rhodamine B by a eutectic solvent extraction-liquid chromatography. The method includes the steps: preparing rhodamine B solution, diluting the solution into different concentrations of rhodamine B standard working solutions, detecting liquid chromatograms of the rhodamine B standard working solutions by the liquid chromatography, and making a calibration curve; preparing eutectic solvent; weighing flavoring oil samples, adding the eutectic solvent and alkane reagents to extract, removing an upper oil layer after centrifugation, and detecting by the liquid chromatography to obtain chromatograms of the samples after residue is washed by alkane; comparing the chromatograms of the samples and the chromatograms of the standard working solutions to determine the nature, and performing quantification according to the concentration of a peak area corresponding to a standard curve. The eutectic solvent comprises a hydrogen-bond acceptor compound and a hydrogen bond donor compound. The method is high in practicability, simple to operate and low in experimental cost, and complicated pretreatment processes are omitted.

The invention provides a pretreatment method for detecting pesticide residues in fresh tea leaves. The method comprises the following steps: selecting a dispersing agent which has high adsorptive property on pesticides such as organic chloride and pyrethroid, directly mixing and grinding the dispersing agent with a fresh leaf sample, so that the cell disruption degree of the sample is improved, and the sample is finally uniformly dispersed; obtaining a mixture in a half-dry state and taking the mixture as a filler, feeding the filler in a chromatographic column in which a certain amount of adsorbents and water removal agents are fed in advance, eluting by using a mixed organic solvent, concentrating an eluant, so that the eluant can be directly subjected to instrumental analysis. According to the method, the operations of extraction and purification of the sample are integrated, and loss of the measured substance caused by sample homogenization, precipitation, centrifugation, dissolution, emulsification and concentration is avoided. Moreover, the method is simple and convenient to operate, high in recovery rate, small in solvent consumption and low in analysis cost and is a green and environment-friendly sample pretreatment method.

The invention provides a method for detecting banned dye in printing ink. The method comprises the following steps of S1, weighing a sample, extracting by adding extract liquor in the sample, and obtaining a to-be-detected sample after concentrating, volume metering and filtering; S2, carrying out qualitative and quantitative analysis on the to-be-detected sample obtained in S1 through an UPLC (Ultra-high Performance Liquid Chromatography)-diode array-mass spectrum combination method, wherein a mass/volume ratio of the sample to the extract liquor in S1 is 1:(15 to 25), the extract liquor is a mixed solution of tetrahydrofuran and methyl alcohol, and a volume ratio of the retrahydrofuran to the methyl alcohol is 1:(3 to 5). According to the method provided by the invention, five kinds of banned dye in the printing ink can be detected in 15 minutes, the linearity within a concentration range being 0.1 to 10 mg/L is good, linear correlation coefficients of the five kinds of banned dye are all greater than 0.995, the detection limit is up to 0.1 mg/L, the relative standard deviation is less than 5 percent, and the sample standard addition recovery is 85 percent to 110 percent.

The invention discloses a method for simultaneously detecting multiple fungal toxins in wheat, and concretely relates to a method for detecting vomitoxin (DON), aflatoxin B1 (AFB1) and zearalenone (ZEN) in wheat through immunoaffinity purification-high performance liquid chromatography. The method comprises the following steps: extracting a sample by using an acetonitrile-water solution having a certain ratio, purifying the obtained sample solution by a composite immunoaffinity column, simultaneously detecting the three fungal toxins through adopting the high performance liquid chromatography,preparing a standard working solution to qualitatively and quantitatively detect the three fungal toxins. Compared with the prior art, the method adopting the immunoaffinity chromatography to greatlyimprove the purifying degree of the sample and adopting the high performance liquid chromatography to realize simultaneous detection of multiple toxins has the advantages of operating time saving, high sensitivity, accuracy in quantification and good repeatability.

The invention claims a hollow-fiber-film-coated molecular imprinting integral adsorption rod, as well as a preparation method and an application thereof. According to the invention, an atrazine molecular imprinting capillary integral extraction head is prepared by using a way of in-situ microwave polymerization in a capillary; the imprinting integral extraction head is coated by using a hollow fiber film and then is used as a solid phase micro-extraction head; by combining a hollow fiver film extraction technology and a high performance liquid chromatography, parameters affecting the extracting efficiency are optimized, such as extraction and analysis solvents, salt concentrations and pH values, extraction and analyzing time, stirring speed and the like; two analysis methods capable of directly extracting triazine herbicides in an environmental water sample are established. The standard recovery rates of detected four triazine herbicide substances are greater than 80% under the optimized experiment conditions. According to the invention, a detection method in which hollow-fiber-film-coated molecular imprinting polymer integral column micro-extraction and an HPLC (High Performance Liquid Chromatography) are combined is established; the detection method has the advantages of simplicity, rapidity, high sensitivity and the like and is suitable for the routine analysis of the water samples.

The invention discloses a method for detecting polycyclic aromatic hydrocarbon in tea oil. The method comprises the following steps: adding a magnetically hydroxylated multiwall carbon nano tube serving as a solid phase extraction reagent into the tea oil diluted by a normal hexane solvent for adsorption of a target substance, carrying out magnetic separation under the action of an external magnetic field, collecting the solid phase extraction reagent with the target substance, removing supernate, purifying the solid phase extraction reagent with the target substance through a purifier, desorbing the target substance on the solid phase extraction reagent through methylbenzene serving as a desorbent, carrying out magnetic separation under the action of the external magnetic field, removing the solid phase extraction reagent, collecting a desorption solution with the target substance, filtering the desorption solution through an organic filter film, and carrying out conventional content measurement by combining gas chromatography and mass spectrum. The method is high in selectivity, low in detection limit, high in sensitivity and high in standard recovery rate.

The invention discloses a mobile phase formulation for measuring carotenoid through liquid chromatography and application of the mobile phase formulation and belongs to the field of methods for separating and metabolizing micromolecules through liquid chromatography. The mobile phase formulation comprises, by volume, A1 phase: 90-100% of methanol-water and B1 phase: 90-100% of tert-butyl methyl ether-methanol. By the mobile phase formulation, chromatograms and testing results of 7-10 carotenoids which are independent in components, good in peak pattern and linear relation, high in adding standard recovery rate and little in relative error can be acquired simply, accurately and quickly (the whole process can be completed within 40min).

The invention relates to a reagent for rapidly measuring total phosphorus in sewage, a preparation method of the reagent and an application. The reagent measures the total phosphorus in the sewage bythe aid of a portable digestion device and a portable spectrophotometer and comprises, by concentration, 1.88mol/L sulfuric acid, 50g/L potassium persulfate solution, 26g/L molybdate solution and 100g/L ascorbic acid solution. The reagent has the advantages that the reagent is convenient to operate and use, reasonable to select, high in testing accuracy, good recovery rate and the like.

The invention belongs to the technical field of drug testing and discloses a method for determining the retention capacity of albendazole (ABZ) in mulberry leaves. According to the method, a solid phase extraction method is adopted for purifying a target substance, and purification adopts an amino solid-phase extraction column; a mixed solution of methyl alcohol-dichloromethane with the volume ratio being (5-20):(80-95) is used for activating the solid-phase extraction column, and a mixed solution of methyl alcohol-dichloromethane with the volume ratio being (1-10):(90-99) is used for drip washing, so that interfering components in the mulberry leaves are almost completely adsorbed by packing of the extraction column, and the target component, namely albendazole, is almost completely eluted out, and thus, the albendazole in the mulberry leaf tissue is separated and enriched well, and a purified sample can be directly quantified through liquid chromatogram. The method has the advantages of simplicity, easiness, low cost, good repeatability of detection result and high degree of accuracy.

A high performance liquid chromatography method for simultaneous determining cellulose, hemicellulose and lignin in tobacco and tobacco products comprises the following steps: S1, crushing and uniformly mixing tobacco and tobacco products, sieving, adding into a G3 sand core funnel, pickling, and filtering to obtain a first product; S2, washing the first product, drying, hydrolyzing with a sulfuric acid solution, and filtering to obtain supernatant and filter residues; S3, washing the filter residues, drying and weighing to obtain first residues with the mass of m1; S4, weighing the first residues after being subjected to ashing treatment, and the mass of the obtained second residues being m2; analyzing the contents of glucose, xylose, arabinose, galactose and mannose in the supernatant byadopting high performance liquid chromatography to obtain the contents of cellulose and hemicellulose; and obtaining the content of lignin according to (m1-m2). The method is simple in pretreatment,accurate in result and short in analysis time, can be used for simultaneously detecting the contents of cellulose, hemicellulose and lignin in tobaccos and tobacco products, and has the advantages ofbatch, rapidness, accuracy and the like.

The invention discloses a method for detecting unmetabolized polycyclic aromatic hydrocarbons in urine on the basis of a low-temperature frozen extraction technology. According to the method, a preprocessing agent is added into a to-be-detected sample, and pulse stimulation is carried out by utilizing an asymmetric phase current so as to improve a binding rate of an indicator and a target object;then after an extraction agent is atomized, the extraction agent is blown into the to-be-extracted sample along with pressurized CO2 gas, and simultaneously, ultrasonic cavitation is carried out, so as to shorten low-temperature extraction time and improve extraction efficiency; then freezing is carried out to remove an extraction phase; and finally, the unmetabolized polycyclic aromatic hydrocarbons in the urine are detected by utilizing a gas chromatography-triple quadrupole tandem mass spectrometry method. According to the invention, interference of various matrices in the sample can be effectively eliminated and analyzed, and sensitivity and reliability are higher.

The invention discloses a detection method of 2, 4-diamino anisole sulfate. According to the method, an Agilentporoshell 120SB-Aq liquid chromatographic column is used, the setting of various parameters is optimized, the relatively high retention degree and relatively high separation efficiency of 2, 4-diamino anisole sulfate in the chromatographic column under an ultrahigh pressure condition canbe achieved, an electrospray ion source mode is employed, and the qualitative and quantitative analysis is carried out in positive ion and multi-reaction monitoring modes. The detection method of theinvention has the advantages of simple pretreatment, easy operation, high sensitivity and rapid and accurate detection, and the requirement for detecting 2, 4-diamino anisole sulfate in textile products can be met.

The present invention discloses a sample pretreatment method for simultaneous detection of malachite green residual liquid chromatography -visible light and fluorescence in freshwater aquaculture water body. The method comprises following specific steps: 20 mL of breeding fresh water is filtered through a membrane, then is placed in a centrifuge tube, then 2 mL of extracting solution I and 20 mL of extracting solution II is added, after thoroughly mixed on a vortex mixer, 15 g of anhydrous sodium sulfate solid is added, after centrifugated at 4500 r/min for 15 min, supernatant in the centrifuge tube is poured into a 100 mL evaporation flask, the solvent is evaporated under reduced pressure using a rotary evaporator, a mass concentration of 1% of potassium borohydride solution and 1 mL of acetonitrile is added to the evaporation flask, after ultrasonic vibration, the solution in the evaporation flask is transferred out, the evaporation flask is washed with 1 mL of acetonitrile, the solution is combined and the volume is adjusted to 3 mL, after filtered by a membrane, sample is injected, and the malachite green residue is simultaneously detected through the liquid chromatography-visible light and fluorescence.