Method for simultaneously and rapidly measuring contents of multiple elements in nano-diamond

Abstract

The invention discloses a method for simultaneously and rapidly measuring the content of multiple elements in nano-diamond, which comprises the following steps: firstly, burning a nano-diamond material in an environment of 850 + / -10 DEG C in the presence of oxygen until the weight is constant, and then dissolving the obtained residue in a solution; preparing 3-5 parts of gradient series mixed standard solutions from the single-element standard solutions according to the content range of a to-be-tested sample; finally, carrying out data acquisition on the emission spectrum light intensity of the standard substance iron, silicon and calcium elements, and drawing a standard working curve of each element according to the corresponding relationship between the element content and the emission spectrum light intensity; and substituting the emission spectrum light intensity of the iron, silicon and calcium elements of the sample to be detected, which is collected by the instrument, into the standard working curve, and calculating the content of the iron, silicon and calcium elements of the sample to be detected. The method solves the problem of sample solution preparation when the nano-diamond is determined by the ICP spectrometer, the sample solution preparation process is simple, and the determination process is not interfered.

Description

Technical Field

[0001] The invention relates to a method for simultaneously and quickly determining the content of multiple elements in nano diamond, and belongs to the field of quality detection. Background Art

[0002] Nanodiamond materials are diamond powders with an average particle size of nanometers. They have the dual characteristics of nanoparticles and superhard materials. Their huge specific surface area, large number of structural defects and surface oxygen-containing functional groups make them have great potential in the development of special new properties. At present, nanodiamonds are mainly used in composite coatings, lubricant additives, abrasive materials and metal-based nanodiamond composite materials.

[0003] The performance of nano-diamond materials is determined by the size of their ash content. The smaller the ash content, the better the performance. The main components of ash are iron, silicon, and calcium. Among them, iron is a harmful element in the use of nano-diamond materials. The lower the content, the better. Therefore, accurate characterization of the content of each element in the material has great guiding significance for the establishment of production technology.

[0004] The characterization methods for such materials are mostly chemical methods, which are characterized by characterizing each element separately. The disadvantages are cumbersome operations, lengthy analysis processes, high analysis costs, and low accuracy.

[0005] Inductively coupled plasma (ICP-AES) emission spectrometry is the most commonly used analytical method for elemental analysis of metal materials. It has the advantages of low detection limit, high sensitivity, good stability, small matrix effect, wide linear range of concentration determination, and simultaneous determination of multiple elements, and has been widely used. Summary of the invention

[0006] The purpose of the present invention is to provide a method for quickly and accurately determining the contents of iron, silicon and calcium in nanodiamond materials by ICP-AES, so as to overcome the shortcomings of the prior art.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for simultaneously and rapidly determining the content of multiple elements in nanodiamonds of the present invention comprises the following steps:

[0009] 1) Preparation method of the sample to be tested: Place the nanodiamond material in a ceramic crucible, burn it to constant weight in an environment with oxygen and 850±10℃, and collect the residue in the crucible for later use;

[0010] 2) Preparation method of sample solution of unknown iron, silicon and calcium content: weigh 0.0100-0.0200g of the residue of unknown element content in step 1), place it in a 200-300ml polytetrafluoroethylene container, add 8-15ml analytical pure hydrofluoric acid, heat it in an environment of 150-180℃ until the reaction is complete; mix it with 20-30ml of hydrochloric acid-nitric acid mixed acid aqueous solution with a volume ratio concentration of 40%-60%, heat it in an environment of 200-230℃ until the reaction is complete; continue to heat until nitric acid smoke appears, transfer it into a 100ml volumetric flask after cooling, dilute it to the scale with deionized water, and wait for testing;

[0011] The volume ratio of hydrochloric acid to nitric acid in the hydrochloric acid-nitric acid mixed acid aqueous solution is 1:3;

[0012] 3) Preparation method of standard solution for drawing working curve: prepare 3-5 parts of series mixed standard solutions with gradient according to the content range of the sample to be tested from the single element standard solution: the content range of each element: iron 10μg / ml-100μg / ml, silicon 5μg / ml-50μg / ml, calcium 5μg / ml-50μg / ml, add the corresponding amount of reagent to each standard solution according to step 2);

[0013] 4) Determination of samples with unknown iron, silicon and calcium content: adjust the working parameters of the inductively coupled plasma emission spectrometer, collect data on the emission spectrum intensity of the series of standard substances iron, silicon and calcium, draw the standard working curve of each element based on the corresponding relationship between the element content and the emission spectrum intensity, bring the emission spectrum intensity of the iron, silicon and calcium elements of the unknown content samples collected by the instrument into the standard working curve, and calculate the iron, silicon and calcium elements content of the unknown content samples;

[0014] 5) Select certified reference materials to verify the accuracy of the test results of the iron, silicon and calcium contents.

[0015] The beneficial effects of the present invention are as follows: a method for rapidly and accurately determining the contents of iron, silicon and calcium in nano-diamond materials by ICP-AES method is provided; the present invention solves the problem of sample solution preparation when the nano-diamond materials are determined by ICP spectrometer, the sample solution preparation process is simple, and no interference is generated in the determination process; the determination method of the present invention can be applied to sample pretreatment technology for element content determination in nano-diamond materials by other element analysis instruments, and has certain application prospects in the field of material analysis. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the embodiments.

[0017] Example

[0018] 1) Place the nanodiamond material in a ceramic crucible, burn it in an oxygen atmosphere at 850±10°C until it reaches a constant weight, and collect the residue in the crucible for later use;

[0019] 2) Weigh 0.0150±0.0002g of the residue in step 1), place it in a 300ml polytetrafluoroethylene container, add 10ml hydrofluoric acid (analytical grade), heat at 160°C until the reaction is complete; mix with 24ml hydrochloric acid-nitric acid mixed acid aqueous solution (volume ratio concentration 50%, hydrochloric acid: nitric acid = 1:3), heat at 220°C until the reaction is complete; continue heating until nitric acid smoke appears, cool and transfer to a 100ml volumetric flask, dilute to the scale with deionized water, and test;

[0020] 3) Prepare a series of mixed standard solutions with gradients from the single element standard solutions according to the content range of the sample to be tested: standard solution 1 (iron 10 μg / ml, silicon 5 μg / ml, calcium 5 μg / ml), standard solution 2 (iron 30 μg / ml, silicon 15 μg / ml, calcium 15 μg / ml), standard solution 3 (iron 60 μg / ml, silicon 30 μg / ml, calcium 30 μg / ml), standard solution 4 (iron 100 μg / ml, silicon 50 μg / ml, calcium 50 μg / ml), add 10 ml of nitric acid aqueous solution (volume ratio concentration 50%) to each standard solution according to step 2), dilute with deionized water to 100 volumetric flask and mix well;

[0021] 4) Using an inductively coupled plasma (ICP-AES) emission spectrometer, set the RF generator power to 1.15kw, the atomization pressure to 26.0psi, the argon flow rate to 0.5L / min, the analysis pump speed to 2.50ml / min, the sample flushing time to 60s, the integration time to 30s for short wave and 10s for long wave; element analysis line (nm) iron 259.940, silicon 251.611, calcium 422.673; collect data for a series of standard substances, draw standard working curves for each element, and determine the element content of the sample to be tested when the linear correlation coefficient of each curve is greater than 0.999;

[0022] 5) Method reliability verification:

[0023] a. The sample solution to be tested is a transparent and uniform solution, indicating that it is completely dissolved;

[0024] b. The relative standard deviation of the sample is less than 2% after ten consecutive tests, which proves that the sample solution is homogeneous and relatively stable and can meet the requirements of instrument analysis;

[0025] c. The recovery rate was tested by the spike method, and the recovery rate of each element was between 99.5% and 100.5%, proving that this method is stable and reliable.

Claims

1. A method for simultaneously and rapidly determining the content of multiple elements in nanodiamonds, characterized in that: The following steps are involved: 1) Preparation method of the sample to be tested: Place the nanodiamond material in a ceramic crucible, burn it to constant weight in an environment with oxygen and 850±10℃, and collect the residue in the crucible for later use; 2) Preparation method of sample solution of unknown iron, silicon and calcium content: weigh 0.0100-0.0200g of the residue of unknown element content in step 1), place it in a 200-300ml polytetrafluoroethylene container, add 8-15ml analytical pure hydrofluoric acid, heat it in an environment of 150-180℃ until the reaction is complete; mix it with 20-30ml of hydrochloric acid-nitric acid mixed acid aqueous solution with a volume ratio concentration of 40%-60%, heat it in an environment of 200-230℃ until the reaction is complete; continue to heat until nitric acid smoke appears, transfer it into a 100ml volumetric flask after cooling, dilute it to the scale with deionized water, and wait for testing; The volume ratio of hydrochloric acid to nitric acid in the hydrochloric acid-nitric acid mixed acid aqueous solution is 1:3; 3) Preparation method of standard solution for drawing working curve: prepare 3-5 parts of series mixed standard solutions with gradient according to the content range of the sample to be tested from the single element standard solution: the content range of each element: iron 10μg / ml-100μg / ml, silicon 5μg / ml-50μg / ml, calcium 5μg / ml-50μg / ml, add the corresponding amount of reagent to each standard solution according to step 2); 4) Determination of samples with unknown iron, silicon and calcium content: adjust the working parameters of the inductively coupled plasma emission spectrometer, collect data on the emission spectrum intensity of the series of standard substances iron, silicon and calcium, draw the standard working curve of each element based on the corresponding relationship between the element content and the emission spectrum intensity, bring the emission spectrum intensity of the iron, silicon and calcium elements of the unknown content samples collected by the instrument into the standard working curve, and calculate the iron, silicon and calcium elements content of the unknown content samples; 5) Select certified reference materials to verify the accuracy of the test results of iron, silicon and calcium content.