阅读说明：本技术 一种氯化钠中铜量的测试方法 (Method for testing copper content in sodium chloride ) 是由 李启华 于 2019-10-14 设计创作，主要内容包括：一种氯化钠中铜量的测试方法,属化学检测技术领域,其包括铜量提取、试液前处理、铜元素-氯化钠基体校准曲线制备,实现了准确检测氯化钠中铜量的目标。测试范围：w(Cu)0.0010×10<Sup>-6</Sup>～1000×10<Sup>-6</Sup>；本发明解决了氯化钠铜量的浓缩提取、试液前处理、铜元素-氯化钠基体校准曲线制备等技术问题,为在国际上广泛使用的人造气氛盐雾腐蚀试验用氯化钠盐溶液的正确制备、金属零件耐腐蚀性评价和预测漆膜耐蚀性及使用寿命,提供了强有力的技术支持。(A method for testing the copper content in sodium chloride belongs to the technical field of chemical detection, and comprises the steps of copper content extraction, test solution pretreatment and preparation of a copper element-sodium chloride matrix calibration curve, so that the aim of accurately detecting the copper content in the sodium chloride is fulfilled. Test range: w (Cu) 0.0010X 10 ‑6 ～1000×10 ‑6 (ii) a The invention solves the technical problems of concentration and extraction of sodium chloride copper amount, pretreatment of test solution, preparation of copper element-sodium chloride matrix calibration curve and the like, and provides powerful technical support for correct preparation of sodium chloride salt solution for artificial atmosphere salt spray corrosion test, corrosion resistance evaluation of metal parts and prediction of corrosion resistance and service life of paint films, which are widely used internationally.)

1. A method for testing the copper content in sodium chloride is characterized by comprising the following steps:

the method comprises the following steps: copper extraction

Weighing 36.0g of a sodium chloride solid sample, placing the sodium chloride solid sample in a 250mL conical flask with a plug, adding 100.0g of ultrapure water, covering a glass plug, shaking up, placing, shaking up till complete dissolution to prepare a sodium chloride approximately saturated solution, adding 100.0g of absolute ethyl alcohol, covering the glass plug, shaking up, placing to form an ethanol-water mixed solution containing copper ions, sodium chloride crystals and other substances;

step two: pretreatment of test solution

Filtering an ethanol-water mixed solution containing copper ions, sodium chloride crystals and other substances by using slow filter paper, discarding about 20mL of primary filtrate, weighing 100.0g of ethanol-water mixed solution filtrate, putting the filtrate into a 250mL beaker, heating, evaporating and concentrating to about 50mL of solution, adding 5mL of superior pure nitric acid, adding 5mL of perchloric acid, continuing heating, evaporating water to the full extent until the solution is in a glass fluid state, taking down the solution to be slightly cold, adding 30mL of 1+5 nitric acid solution to dissolve salts, transferring the solution into a 100mL volumetric flask, diluting to a scale by using ultrapure water, shaking uniformly, and simultaneously performing a blank test;

step three: preparation of standard solution of copper element

Heating and dissolving 1.0000g of metal copper with the purity of more than or equal to 99.9 percent in 30mL of 1+1 nitric acid solution, cooling, moving into a 1000mL volumetric flask, flatly shaking the volumetric flask for several times when the volume is diluted to about 3/4 volumes by using ultrapure water, primarily mixing the metal copper uniformly, then continuously adding the ultrapure water, carefully dropwise adding the ultrapure water by using a dropper when the volume is close to a scale line until the lowest point of the lower meniscus of the copper element solution is tangent to the scale line, tightly covering a glass plug, pressing the glass plug by using a forefinger of a left hand, pressing the bottom edge of the bottle by using a fingertip of the right hand, inverting the volumetric flask, shaking the volumetric flask, inverting the volumetric flask again to enable bubbles in the solution to rise to the top end, repeating the steps for 10-15 times, and mixing the solution uniformly to obtain a copper element standard solution No. 0, wherein 1 mL;

transferring 50.00mL of copper element standard solution 0#, 1mL of copper element standard solution containing 1mg of copper, placing the solution in a 100mL volumetric flask, adding 10mL of 1+1 nitric acid solution, diluting with ultrapure water to a scale, and uniformly mixing to obtain copper element standard solution I, wherein 1mL of the solution contains 500 mu g of copper;

transferring 1.00mL of copper element standard solution I, wherein 1mL of the solution contains 500 mu g of copper, placing the solution in a 100mL volumetric flask, adding 10mL of 1+1 nitric acid solution, diluting with ultrapure water to scale, and uniformly mixing to obtain copper element standard solution II, wherein 1mL of the solution contains 5.00 mu g of copper;

transferring 1.00mL of copper element standard solution II, putting 1mL of the solution containing 5.00 mu g of copper into a 100mL volumetric flask, adding 10mL of 1+1 nitric acid solution, diluting with ultrapure water to a scale, and uniformly mixing to obtain copper element standard solution III, wherein 1mL of the solution containing 0.050 mu g of copper;

step four: preparation of calibration curve of copper element-sodium chloride matrix

The copper element-sodium chloride matrix calibration curve ① is prepared by weighing six parts of 8.0g sodium chloride reference reagent, placing in a 100mL volumetric flask, adding 30mL 1+5 nitric acid solution to dissolve salt, adding 0.00, 0.50, 2.00, 5.00, 10.00, 40.00mL copper element standard solution III, diluting the solution 1mL containing 0.050 μ g copper with ultrapure water to scale, mixing well, and testing w (Cu)0.0010 × 10^-6～0.10×10^-6；

The copper element-sodium chloride matrix calibration curve ② is prepared by weighing six parts of 8.0g sodium chloride reference reagent, placing in a 100mL volumetric flask, adding 30mL 1+5 nitric acid solution to dissolve salt, adding 0.00, 0.50, 2.00, 5.00, 10.00, 40.00mL copper element standard solution II, 1mL copper containing 5.00 μ g with ultrapure water, diluting to scale, mixing, and testing w (Cu)0.10 × 10^-6～10.0×10^-6；

The calibration curve ③ is prepared by weighing six parts of 8.0g sodium chloride reference reagent, placing in a 100mL volumetric flask, adding 30mL 1+5 nitric acid solution to dissolve salts, and adding 0.00, 0.50, 2.00, 5.00, 10.00, and 40.00mL copper element standardA quasi-solution I, 1mL of which contains 500. mu.g of copper, is diluted to the scale with ultrapure water and mixed well, suitable for testing w (Cu) 10.0X 10^-6～1000×10^-6；

Step five: dual platinum mesh atomizer adjustment

Selecting a double-platinum-mesh atomizer to atomize the test solution, rotationally detaching one end of a metal platinum mesh in the double-platinum-mesh atomizer before use, taking out the semitransparent granular solid in the double-platinum-mesh atomizer, cleaning the double-platinum-mesh of the atomizer by ultrapure water, rotationally installing one end of the metal platinum mesh of the detached double-platinum-mesh atomizer, and screwing;

step six: optimization of instrument operating conditions

And starting the inductively coupled plasma atomic emission spectrometer, and preheating the instrument equipment for more than 2 h. Optimizing the working conditions of the instrument according to the instrument specification, and selecting proper measurement conditions such as argon pressure, observation height, analysis line, flushing time, integration times and the like;

and (3) selecting optimized measurement conditions as recommended working parameters by using a Prodigy XP inductively coupled plasma atomic emission spectrometer. RF power: 1100W; argon gas input pressure: 85-95 PSI; cooling air flow: 19L/min; auxiliary air flow rate: 0.0L/min; liquid inlet flow rate of a peristaltic pump: 1.4 mL/min; atomizing gas pressure: 52 PSI; plasma torch observation height: 15 mm; sample introduction time: 30 s; integration time: 10 s; argon purity: not less than 99.99%;

after the working conditions of the instrument are optimized, comprehensively considering the content range of copper elements, the linear relation, the recovery rate and the accuracy of the detection result in an element test wavelength spectral line, and selecting a proper test wavelength, wherein the selected test wavelength is as follows: cu324.754nm, 327.396nm and 224.700 nm;

step seven: inductively coupled plasma atomic emission spectrometer detection

Clicking the plasma torch to automatically start to ignite, confirming that the operation parameters of the instrument are in a normal range after ignition, enabling the atomization system and the plasma flame to work normally, and stabilizing the instrument for more than 15 min;

on an inductively coupled plasma atomic emission spectrometer, measuring the spectral intensity of copper element in a solution to be measured and a sample solution with a copper element-sodium chloride matrix calibration curve ① - ③, subtracting the spectral intensity of a blank solution from each spectral intensity to obtain the net spectral intensity, automatically reading the content rho (Cu) of the copper element in the sample solution by an instrument, and pumping a test solution after yellow flame of the plasma disappears in the detection process;

step eight: calculation of analysis results

Calculating the mass fraction of copper in the sodium chloride according to the mass concentration of copper element in the sample solution and expressed by mu g/mL;

the amount of copper in the sodium chloride sample is calculated according to the following formula (1) in terms of mass fraction w (Cu):

in the formula:

ρ (Cu) -the value of the mass concentration of copper in the test solution in milligrams per milliliter (. mu.g/mL);

v is the value of the volume of the fluid to be tested in milliliters (mL);

m is the value of the mass of the sample in grams (g).

Technical Field

The invention belongs to the field of chemical detection, and particularly relates to a method for testing the copper content in sodium chloride, namely a method for testing the copper content in sodium chloride by using an ethanol-water mixed solution extraction method, wherein the test range is as follows: w (Cu) 0.0010X 10^-6～1000×10^-6。

Background

Plasma emission spectroscopy (edited by sinrenxuan, chemical industry press, 1 st edition 2005), page 228, there is a test method for S, B, Na, Ca elements in seawater, and the spectrometer is ARL 35000, which is not related to the test method for Cu elements in seawater; page 231, trace elements in the seawater are extracted and enriched, although Cu elements exist, an organic solvent with extremely high toxicity is needed for extraction and enrichment, meanwhile, a pyrrolidine ammonium disulfide reagent, a nitrobenzene diluent and the like are also needed to be added, and the blank value is increased due to the purity problem; on page 232, separation, enrichment and testing of trace elements in saturated refined brine are performed, the saturated refined brine is evaporated to dryness, and due to the fact that the evaporation process is long, pollution phenomena such as dissolution of the trace elements in a container are prone to occurring, and a testing method of a Cu element in the saturated refined brine is not involved; no method for preparing a calibration curve of a copper element-sodium chloride matrix by using sodium chloride is available. At present, no effective national standard, industrial standard, local standard and enterprise standard sodium chloride copper chemical analysis method is available. At present, no method for extracting metal elements such as copper in sodium chloride by using ethanol-water mixed solution exists.

In the technical conditions of GB/T1266-2006 sodium chloride chemical reagent, the technical index requirements of copper content are not seen; GB/T10125-2012 salt fog test for artificial atmosphere corrosion test requires that the copper content in sodium chloride is not more than 0.001%; GB/T2423.17-2008 "environmental test for Electrical and electronic products part 2: test methods test Ka: salt fog, the total amount of impurities in sodium chloride is required to be not more than 0.3%, and the amount of copper is not independently required; ASTM B117-2016 salt fog test requires that the amount of copper in sodium chloride be no greater than 0.3X 10^-6。

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide a method for testing the copper content in sodium chloride.

The invention relates to a method for testing the copper content in sodium chloride, which comprises the following steps: 36.0g of a sodium chloride solid sample was weighed, 100.0g of ultrapure water was added thereto and dissolved completely, and then 100.0g of anhydrous ethanol was added thereto to form an ethanol-water mixed solution containing copper ions, sodium chloride crystals and the like, and the ethanol-water mixed solution was subjected to ethanol-water mixing. Then, the sample solution is pretreated: filtering, weighing 100.0g of ethanol-water mixed solution filtrate, concentrating, adding 5mL of nitric acid, adding 5mL of perchloric acid, continuously heating to evaporate off all organic matters, adding 30mL of 1+5 nitric acid solution to dissolve salts, diluting to 100mL with ultrapure water, shaking uniformly, and simultaneously performing a blank test. Then preparing a calibration curve of the copper element-sodium chloride matrix: weighing six parts of 8.0g of sodium chloride reference reagent, adding 30mL of 1+5 nitric acid solution to dissolve salts, respectively adding different amounts of copper element standard solutions, diluting to scale with ultrapure water, and uniformly mixing.

On an inductively coupled plasma atomic emission spectrometer, a double platinum mesh atomizer is selected to respectively test a copper element-sodium chloride matrix calibration curve and the emission light intensity of a copper element in a test solution, a detection instrument device automatically displays the mass concentration of the copper element in the test solution, and then the mass fraction of copper in a test material is obtained through conversion.

The invention has the beneficial effects that:

the method for testing the copper content in the sodium chloride has the following characteristics:

1. establishes a chemical detection method of the copper content in the sodium chloride, namely an ethanol-water mixed solution extraction method;

2. the chemical detection of the copper content in the sodium chloride is free of the existing reliable chemical analysis method of national standard, industrial standard, local standard and enterprise standard;

3. the problem of serious interference of a large amount of sodium chloride matrixes is solved;

4. the technical problems of concentration and extraction of the amount of sodium chloride and copper, pretreatment of a test solution, preparation of a calibration curve of a copper element-sodium chloride matrix and the like are solved;

5. test range: w (Cu) 0.1X 10^-6～100×10^-6；

6. Precision:

TABLE 1 reproducibility values

Detailed Description

The present invention will be described in detail with reference to examples.