36 results about "Isotope-ratio mass spectrometry" patented technology

The invention relates to a method for distinguishing true apple juice from false apple juice by virtue of liquid chromatogram- isotope ratio mass spectrometry (LC-IRMS) determination. The method can be used for effectively distinguishing true apple juice from false apple juice and ensuring the quality safety of apple juice products. The method comprises the following steps: respectively preparing apples from different places into apple juice samples; analyzing plant polysaccharides in the prepared apple juice samples to establish plant polysaccharide determination conditions, and analyzing malic acid in the apple juice to establish the plant polysaccharide determination conditions; and analyzing natural apple juice to establish a linear relationship between the delta <13>C ratio of plant polysaccharides and malic acid in the apple juice to make judgment on the true and false apple juice, wherein if the delta <13>Csuc (sucrose) ranges from -1.909% to -2.647%, the delta <13>Cglu (glucose) ranges from -2.452% to -3.050%, the delta <13>Cfru (fructose) ranges from 2.522% to 3.196%, the ratio delta 1 of plant polysaccharides ranges from 0.27 to 2.78, the delta <13>Cmal (malic acid) ranges from -2.531% to 3.257% and the linear dependence coefficient R2 is more than 0.7255, the apple juice is true. The method is accurate in determination results and high in sensitivity, the quality of apple juice can be effectively guaranteed, adulterated apple juice can be prevented from causing injury to consumers, and economic and social benefits are tremendous.

A method for evaluating the acidity of oil samples in small amounts, applicable at any stage of the petroleum industry, includes labelling by an isotope of a chemical element present in at least one acid function present in petroleum samples. Isotopic enrichment of the samples is then determined by isotope ratio mass spectrometry (IRMS). The acidity of the samples is deduced therefrom. This method is an alternative to the measurement of the Total Acid Number (TAN). In particular, it represents the only possibility to reliably measure the acidity of oil samples available in small amounts. The method can be applied to the economic evaluation of a hydrocarbon production field, to the determination of the carbon range responsible for the acidity of a crude, or to monitoring of the evolution of the acid distribution of a site polluted by hydrocarbons.

The invention relates to a method for detecting a potato addition amount in a staple food product. The method for detecting the potato addition amount in the staple food product mainly comprises the following steps: (1) preparing a sample; (2) performing pretreatment on the sample; (3) using the isotope ratio mass spectrometry for detecting to obtain a stable isotope relative ratio of carbon, nitrogen, hydrogen and oxygen; and (4) performing qualitative and quantitative analysis by means of a chemometric method, determining whether the potato is added or not by means of discriminant analysis,and determining the amount of addition by means of a multiple linear regression equation. Compared with the prior art, the method for detecting the potato addition amount in the staple food product has the advantages of simple operation, convenient and rapid, high detection efficiency, high accuracy, good stability and reproducibility; no method for detecting the potato content in potato productsexists in the current national standard; and the invention not only can qualitatively determine whether the product adds the mashed potato or not, but also can quantitatively analyze the addition amount of the mashed potato, which has a good market application prospect.

The invention discloses a method for identifying the producing area of Heishan brown shell eggs. The method comprises the following steps: respectively pretreating egg samples from different producing areas; measuring the isotope ratio and mineral element content of the pretreated eggs by using isotope ratio mass spectrometry and inductively coupled plasma mass spectrometry; screening out difference traceability indexes among different regions by combining a chemometrics method, and establishing a Fisher function discrimination model by applying the screened traceability indexes; determining the producing area of the brown shell egg sample to be detected by comparing the size of the Fisher function discrimination model. According to the method, Fisher function discrimination models of the brown-shell eggs from three producing areas of Heishan County, Heishan County surroundings and Hebei are established for the first time, the original classification discrimination accuracy is 100.0%, the cross validation accuracy is 98.5% by utilizing the models, the discrimination accuracy is high, the stability is good, effective source tracing of geographical indication products and non-geographical indication brown-shell eggs of the Heishan brown shell eggs is realized, technical support is provided for Heishan brown shell egg production place confirmation and further protection.

Isotope ratio mass spectrometry is effected by: injecting a sample for analysis into a gas chromatography column; directing an effluent from the gas chromatography column to a switching arrangement; and selecting a configuration of the switching arrangement, such that: in a first mode, the effluent from the gas chromatography column is provided as an input to a peak broadener; and in a second mode, an effluent from the peak broadener is provided to a mass spectrometer for isotope ratio mass spectrometry without the effluent from the gas chromatography column being provided as an input to the peak broadener.

The invention relates to an online analysis method for hydrocarbon carbon isotope of a light dydrocarbon monomer of source rock pyrolysis products. The method comprises the following steps: placing source rock sample particles into a sample pipe; connecting the sample pipe with a sample inlet of a gas chromatograph; adjusting the pressure of carrier gas of a pyrolyzer to 15 to 18psi; introducing the carrier gas to a pyrolyzing furnace for 5 to 10 minutes, and fully filling a liquid nitrogen cold trap with liquid nitrogen; heating the pyrolyzing furnace to be at a preset temperature, keeping the temperature for 30 minutes to obtain a hydrocarbon compound; lowering the temperature of the pyrolyzing furnace to 80 to 85 DEG C, removing the liquid nitrogen cold trap, and starting the gas chromatograph and an isotope ratio mass spectrometry; separating the hydrocarbon compound to single-molecule hydrocarbon compounds by the gas chromatograph; burning the single-molecule hydrocarbon compounds to obtain CO2; measuring the carbon isotope ratio of the CO2 by the isotope ratio mass spectrometry; and recording the carbon isotope ratio and generating a mass spectrum. The method provided by the invention has the characteristics of being high in reliability, convenient to operate, quick in analysis, and low in analysis cost.

The invention discloses a fluid inclusion water hydrogen isotope analysis system. The fluid inclusion water hydrogen isotope analysis system comprises a water sample collection instrument and a TC / EA-IRMS combination instrument; the water sample collection instrument comprises a vacuum communication pipeline, a sample cracking device and a water sample collection device; the water sample collection device comprises a quartz collection tube, and a capillary tube part is formed on the lower end of the quartz collection tube; the TC / EA-IRMS combination instrument comprises a high-temperature splitting / element analyzer (TC / EA) and an isotope ratio mass spectrometry (IRMS), and the high-temperature splitting / element analyzer comprises a high-temperature reaction tube and a gas chromatographic column; by adopting the capillary tube part and a solid feeding way, the relatively small sample amount is needed, and the sample amount of the fluid inclusion can be effectively reduced.

The invention provides a method for determining the cadmium isotope ratio in rice by multi-receiver inductively coupled plasma mass spectrometry. The total cadmium content of the rice sample is obtained to obtain the separation and purification rate; step 3 is to perform microwave digestion on the rice sample to be tested to separate and purify the test liquid; step 4 uses multi-receiver inductively coupled plasma mass spectrometry to determine the cadmium isotope ratio in the test liquid; wherein, The separation and purification are specifically as follows: a, the nitric acid medium of the digestion solution is converted into a hydrochloric acid medium; b, the digestion solution of the hydrochloric acid medium is first rinsed with hydrochloric acid 5 times, and then washed twice with Milli-Q water to obtain an eluent; c to The eluent is eluted and collected; d, the eluent is changed from a hydrochloric acid medium to a nitric acid medium. The invention solves the technical problem of separation and purification of cadmium in rice samples with low cadmium content, can quickly and accurately restore the source of cadmium pollution, and has good application value.

The invention discloses a method for simultaneously measuring the composition of natural nitrate and nitrite nitrogen and oxygen isotopes, quantitatively converting nitrate and nitrite into corresponding organic esters and nitro compounds, and then adopting gas chromatography / pyrolysis / Simultaneous Determination of Nitric Acid and Nitrite δ by Gas Chromatography / Isotope Ratio Mass Spectrometry 18 O and delta 15 N determination. The method for simultaneously measuring the nitrogen and oxygen isotope composition of natural nitrate and nitrite of the present invention requires less sample consumption and does not cause loss, gain, exchange and fractionation of nitrogen and oxygen.

A mass spectrometry method comprising steps of generating an ion beam from an ion source; directing the ion beam into a collision cell; introducing into the collision cell through a gas inlet on the collision cell a charge-neutral analyte gas or reaction gas; ionizing the analyte gas or reaction gas in the collision cell by means of collisions between the analyte gas or reaction gas and the ion beam; transmitting ions from the ionized analyte gas or reaction gas from the collision cell into a mass analyzer; and mass analyzing the transmitted ions of the ionized analyte or reaction gas. The methods can be applied in isotope ratio mass spectrometry to determine the isotope abundance or isotope ratio of a reaction gas used in mass shift reactions between the gas and sample ions, to determine a corrected isotope abundance or ratio of the sample ions.

The invention relates to a method for distinguishing true apple juice from false apple juice by virtue of liquid chromatogram- isotope ratio mass spectrometry (LC-IRMS) determination. The method can be used for effectively distinguishing true apple juice from false apple juice and ensuring the quality safety of apple juice products. The method comprises the following steps: respectively preparing apples from different places into apple juice samples; analyzing plant polysaccharides in the prepared apple juice samples to establish plant polysaccharide determination conditions, and analyzing malic acid in the apple juice to establish the plant polysaccharide determination conditions; and analyzing natural apple juice to establish a linear relationship between the delta <13>C ratio of plant polysaccharides and malic acid in the apple juice to make judgment on the true and false apple juice, wherein if the delta <13>Csuc (sucrose) ranges from -1.909% to -2.647%, the delta <13>Cglu (glucose) ranges from -2.452% to -3.050%, the delta <13>Cfru (fructose) ranges from 2.522% to 3.196%, the ratio delta 1 of plant polysaccharides ranges from 0.27 to 2.78, the delta <13>Cmal (malic acid) ranges from -2.531% to 3.257% and the linear dependence coefficient R2 is more than 0.7255, the apple juice is true. The method is accurate in determination results and high in sensitivity, the quality of apple juice can be effectively guaranteed, adulterated apple juice can be prevented from causing injury to consumers, and economic and social benefits are tremendous.

The present application relates to methods and apparatus for isotope ratio mass spectrometry. Isotope ratio mass spectrometry comprising: flowing through a separation device a liquid mobile phase containing a sample comprising at least one molecular species having an isotope ratio to be determined; Set or reduce the flow rate of the liquid mobile phase flowing through the separation device over time to achieve the desired isotope ratio accuracy; at least for the at least one molecular species that has emerged from the separation device while setting or reducing the flow rate performing mass analysis; determining at least one isotope ratio of said at least one molecular species from mass peak intensities of at least two isotopologues of said at least one molecular species according to said mass analysis, said mass analysis passing being sufficiently high to resolve between The mass resolution of the two most abundant mass peaks of the nominal mass of at least one of the isotopologues is performed.

In a mass spectrometer, a mass-to-charge dispersive element separates received ions spatially according to their mass-to-charge ratios, to provide a dispersed ion beam thereby. An ion detection arrangement that detects the dispersed ion beam comprises: at least one primary ion detector, each detecting spatially separated ions having mass-to-charge ratios within a respective desired range and each providing a respective main beam signal based on its respective detected ions; and at least one secondary ion detector, each detecting ions having mass-to-charge ratios outside all of the desired ranges simultaneously with the at least one primary ion detector detecting the spatially separated ions and each providing a respective background signal based on its respective detected ions. At least one mass intensity measurement is provided for the received ions having a mass-to-charge ratio within the desired range, based on the at least one main beam signal and the at least one background signal.

The invention relates to a method for detecting a potato addition amount in a staple food product. The method for detecting the potato addition amount in the staple food product mainly comprises the following steps: (1) preparing a sample; (2) performing pretreatment on the sample; (3) using the isotope ratio mass spectrometry for detecting to obtain a stable isotope relative ratio of carbon, nitrogen, hydrogen and oxygen; and (4) performing qualitative and quantitative analysis by means of a chemometric method, determining whether the potato is added or not by means of discriminant analysis,and determining the amount of addition by means of a multiple linear regression equation. Compared with the prior art, the method for detecting the potato addition amount in the staple food product has the advantages of simple operation, convenient and rapid, high detection efficiency, high accuracy, good stability and reproducibility; no method for detecting the potato content in potato productsexists in the current national standard; and the invention not only can qualitatively determine whether the product adds the mashed potato or not, but also can quantitatively analyze the addition amount of the mashed potato, which has a good market application prospect.

The invention provides a calibration method for measuring trace elements in a sample by isotope dilution mass spectrometry, belonging to the field of isotope dilution mass spectrometry. When the isotope dilution mass spectrometry is used to determine the trace elements in the sample to be tested, when the isotope abundance ratios of the measured elements in the standard substance solution and the sample solution to be tested are not equal due to the interference of the matrix, the trace elements in the standard substance solution are determined respectively. The isotopic abundance ratio of the measured element and the isotopic abundance ratio of the measured element in the sample solution to be measured, and then calculate the correction coefficient K according to the correction method of the present invention; then use the K value to correct the measured value related to the sample to be measured , and finally realize the accurate determination of the content of trace elements in the sample to be tested by isotope dilution mass spectrometry. The method solves the influence of matrix interference of the sample to be tested on the determination accuracy when the content of trace elements in the sample to be tested is determined by isotope dilution mass spectrometry.

The invention relates to an oxidation reaction device for a specific compound carbon isotope analysis system, which comprises an oxidation heating furnace, a power wire and a thermocouple, wherein an oxidating-catalytic material is filled in the oxidation heating furnace; both ends of the oxidation heating furnace are respectively provided with a first ceramic capillary chromatographic column and a second ceramic capillary chromatographic column; the first ceramic capillary chromatographic column and the second capillary chromatographic column are respectively connected with a first oxidation device interface and a second oxidation device interface; the first oxidation device interface is connected with a gas chromatogram; the second oxidation device interface is connected with a drying device; and the drying device is connected with an isotopic ratio mass spectrogram. The test on hydrocarbon samples with different carbon numbers by using the oxidation reaction device indicates that the testing accuracy of the carbon isotope value is better than + / -(0.02-0.05)%, thereby satisfying the research demands, effectively lowering the analysis cost and having favorable application and popularization values.

The invention discloses a method for measuring the nitrogen concentration based on a trace-gas preconcentration device-isotope ratio mass spectrometer (PreCon-IRMS). The method includes the steps that an isotope ratio mass spectrum serves as a nitrogen detector, the m / z 28 ion current intensity of a to-be-detected nitrogen sample is directly measured through the PreCon-IRMS, and then the concentration of the to-be-detected nitrogen sample is calculated according to the linear relationship between the m / z 28 ion current intensity of a standard nitrogen sample and the concentration. The method is easy to operate and short in measuring time.