Method for detecting content of sulfur element in fingerprint-resistant liquid

Abstract

The invention relates to the technical field of detection and assay, in particular to a method for detecting the content of a sulfur element in fingerprint-resistant liquid. The method comprises the following steps: adding concentrated nitric acid and concentrated hydrochloric acid into a stock solution of a fingerprint-resistant solution, and heating at low temperature to obtain a precipitate and a main solution; burning, and adding concentrated nitric acid, hydrofluoric acid and perchloric acid for treatment to obtain a solution to be detected; and finally, detecting by using an inductively coupled plasma spectrometer, obtaining a sulfur element content detection value in the solution to be detected by using a standard curve method, and calculating to obtain the sulfur element content in the fingerprint-resistant stock solution. The method disclosed by the invention is low in sample treatment cost, simple in sample treatment step, less in used chemical reagent and less in environmental influence, only needs laboratory infrastructure, and is suitable for most laboratories to use.

Description

Technical Field

[0001] The invention relates to the technical field of testing and analysis, and in particular to a method for detecting the content of sulfur in anti-fingerprint liquid. Background Art

[0002] In the late 1970s and early 1980s, with the rapid development of the electronics and automobile industries, the demand for galvanized steel sheets soared. At this stage, galvanized sheets were only passivated or phosphated before painting or processing. However, it was found during the production process that the fingerprints of workers would stick to the surface of the galvanized sheet, forming a "black spot" phenomenon, which reduced the appearance quality and re-painting adhesion of the galvanized sheet. At the same time, there are certain requirements for the lubricity of the galvanized sheet during production.

[0003] To solve this problem, steel companies initiated research on anti-fingerprint treatment technology for galvanized steel sheets. The first generation of anti-fingerprint film is obtained by coating the surface of galvanized steel sheets with inorganic silicates after chromate passivation; the second generation is obtained by replacing the inorganic silicate coating with a solvent-based organic resin coating; the third generation is obtained by compounding chromate passivation agents with water-based resins; with the improvement of environmental protection requirements, chromium-free anti-fingerprint film technology has emerged.

[0004] The anti-fingerprint film needs to have multiple properties such as corrosion resistance, conductivity, coating, and lubricity, so the composition of the anti-fingerprint liquid is relatively complex. The sulfur element in the anti-fingerprint liquid will become a component of the anti-fingerprint film as the film is formed. As customers' requirements for the quality of anti-fingerprint galvanized steel sheets increase, the evaluation indicators of anti-fingerprint films are becoming more and more extensive, and the content range of sulfur in the anti-fingerprint film is limited. Therefore, it is necessary to detect the sulfur element in the anti-fingerprint liquid to ensure the quality of the anti-fingerprint galvanized steel sheet products. Summary of the invention

[0005] The purpose of the present invention is to provide a method for detecting the sulfur content in anti-fingerprint liquid. By detecting the sulfur content in the anti-fingerprint liquid, it is judged whether the purchased anti-fingerprint liquid meets the production needs, so as to ensure the product quality of the anti-fingerprint galvanized steel plate.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] The present invention provides a method for detecting the sulfur content in anti-fingerprint liquid, the method comprising the following steps:

[0008] (1) Weigh 10-20 mL of the original solution of the anti-fingerprint liquid and place it in a polytetrafluoroethylene beaker, add 7-15 mL of concentrated nitric acid and 7-15 mL of concentrated hydrochloric acid, heat the sample at 150-200° C. until the yellow smoke of the sample is gone and there is no more foam, add deionized water to dilute the volume to 100-150 mL, filter with filter paper, wash with deionized water, collect the precipitate and wrap it with filter paper, and collect the filtrate and washing liquid as the main liquid;

[0009] (2) Place the precipitate wrapped with filter paper in a crucible, dry, incinerate the filter paper, calcine at 700-800°C for 30-50 min, cool, transfer the precipitate into a polytetrafluoroethylene beaker, add 1-2 mL of deionized water to moisten the precipitate, add 7-15 mL of concentrated nitric acid and 7-15 mL of hydrofluoric acid, heat to dissolve the precipitate, then add 5-10 mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool slightly, add 10-15 mL of dilute hydrochloric acid, heat to dissolve the salts, combine the solution with the main solution after cooling, heat to concentrate the volume, transfer to a 100 mL volumetric flask, dilute, and fix the volume to obtain a test solution;

[0010] (3) preparing sulfur standard curve solutions with different concentration gradients, setting the working conditions of the inductively coupled plasma spectrometer, testing each solution to obtain a standard curve, and testing the test solution obtained in step (2) under the same working conditions to obtain the sulfur content detection value in the test solution, and calculating the sulfur content in the anti-fingerprint liquid stock solution.

[0011] In the above technical solution, further, in step (1), the precipitate is rinsed with deionized water 5 to 7 times.

[0012] In the above technical solution, further, in step (2), the dilute hydrochloric acid is prepared by concentrating hydrochloric acid and deionized water, and the volume ratio of the concentrated hydrochloric acid to the deionized water is 1:1.

[0013] In the above technical solution, further, in step (2), the crucible is a porcelain crucible.

[0014] In the above technical solution, further, in step (3), the concentration range of the sulfur element standard curve solution is 0 to 50 μg / mL.

[0015] In the above technical solution, further, in step (3), the formula used for calculation is as follows:

[0016]

[0017] in:

[0018] c-the sulfur content of the solution to be tested, μg / mL;

[0019] V1 - volume of the solution to be tested, mL;

[0020] V0 - volume of anti-fingerprint liquid, mL;

[0021] S - sulfur content in the anti-fingerprint liquid, μg / mL.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention realizes the detection of sulfur element in anti-fingerprint liquid to ensure the product quality of anti-fingerprint galvanized steel sheet.

[0024] 2. The sample processing cost of the method of the present invention is low, the sample processing steps are simple, less chemical reagents are used, and the impact on the environment is small.

[0025] 3. The method of the present invention only requires basic laboratory equipment and is suitable for use in most laboratories. DETAILED DESCRIPTION

[0026] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0027] In the following examples, the concentration of hydrofluoric acid used is 40 wt %, the concentration of concentrated nitric acid is 65 wt %, the concentration of concentrated hydrochloric acid is 37 wt %, and the concentration of perchloric acid is 71 wt %.

[0028] The inductively coupled plasma spectrometer used was iCAP7400 from Thermo Fisher Scientific, and the operating conditions were: high-frequency transmission power 1150 W; peristaltic pump speed 60 r / min; nebulizer gas flow rate 0.6 L / min; auxiliary gas flow rate 0.5 L / min; detector measurement temperature -47 °C; light chamber temperature 38 °C; observation height 15 mm; integration time long wave / short wave 10 s.

[0029] The accuracy was verified by the standard addition method.

[0030] Example 1

[0031] (1) Take 1 # Put 10mL of anti-fingerprint liquid into a polytetrafluoroethylene beaker, add 7mL of concentrated nitric acid and 7mL of concentrated hydrochloric acid, heat at 150℃ until the yellow smoke of the sample disappears and there is no more foam, add deionized water to the beaker to dilute the volume to 100mL, filter quickly with filter paper, transfer all the precipitate to the filter paper, rinse the original beaker and precipitate with deionized water 5 to 7 times, collect the filtrate and washing liquid in a clean beaker as the main liquid, and wrap the precipitate with filter paper;

[0032] (2) Place the precipitate wrapped with filter paper in a porcelain crucible, dry it, incinerate the filter paper, burn it in a high-temperature furnace at 700°C for 30 minutes, cool it, transfer the precipitate to the original polytetrafluoroethylene beaker, add 1mL of deionized water to moisten the precipitate, add 7mL of concentrated nitric acid and 7mL of hydrofluoric acid, heat to dissolve the precipitate, then add 5mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool it slightly, add 10mL of dilute hydrochloric acid prepared by concentrated hydrochloric acid and deionized water in a volume ratio of 1:1, heat to dissolve the salts, cool it, combine the solution with the main solution, heat to concentrate the volume, transfer it to a 100mL volumetric flask, dilute it, and make it up to volume to obtain the test solution;

[0033] (3) Take 1000 μg / mL of sulfur standard solution and dilute it step by step to obtain sulfur calibration curve solution. The concentrations of sulfur calibration curve solution are: 0 μg / mL, 1 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL, 20 μg / mL, respectively. Use inductively coupled plasma spectrometer to measure each solution to obtain a standard curve. Then use inductively coupled plasma spectrometer to measure the solution to be tested. The sulfur content of the solution to be tested is obtained by annotating the curve. The sulfur content in the fingerprint-resistant liquid is calculated by the following formula:

[0034]

[0035] in:

[0036] c-the sulfur content of the solution to be tested, μg / mL;

[0037] V1 - volume of the solution to be tested, mL;

[0038] V0 - volume of anti-fingerprint liquid, mL;

[0039] S - sulfur content in the anti-fingerprint liquid, μg / mL.

[0040] In Example 1, 1 # The sulfur content of the anti-fingerprint liquid is 8.03μg / mL.

[0041] Take 1 # 10 mL of anti-fingerprint liquid was placed in a polytetrafluoroethylene beaker, and 1 mL of 100 μg / mL sulfur standard solution was added. The operation was carried out according to steps (1), (2), and (3). The value of the spiked sample was 1.806 μg / mL. The spiked recovery was calculated using the following formula:

[0042] Spiked recovery rate (%) = (spike sample measurement value - sample measurement value) ÷ spike amount × 100%

[0043] 1 # The recovery rate of the anti-fingerprint liquid spiked was 100.3%.

[0044] Example 2

[0045] (1) Take 2 # Put 12mL of anti-fingerprint liquid into a polytetrafluoroethylene beaker, add 9mL of concentrated nitric acid and 9mL of concentrated hydrochloric acid, heat at 160℃ until the yellow smoke of the sample disappears and there is no more foam, add deionized water to the beaker to dilute the volume to 110mL, filter quickly with filter paper, transfer all the precipitate to the filter paper, rinse the original beaker and precipitate with deionized water 5 to 7 times, collect the filtrate and washing liquid in a clean beaker as the main liquid, and wrap the precipitate with filter paper;

[0046] (2) Place the precipitate wrapped with filter paper in a porcelain crucible, dry it, incinerate the filter paper, burn it in a high-temperature furnace at 720°C for 35 minutes, cool it, transfer the precipitate to the original polytetrafluoroethylene beaker, add 1mL of deionized water to moisten the precipitate, add 9mL of concentrated nitric acid and 9mL of hydrofluoric acid, heat to dissolve the precipitate, then add 5mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool it slightly, add 10mL of dilute hydrochloric acid prepared by concentrated hydrochloric acid and deionized water in a volume ratio of 1:1, heat to dissolve the salts, cool it, combine the solution with the main solution, heat to concentrate the volume, transfer it to a 100mL volumetric flask, dilute it, and make it up to volume to obtain the test solution;

[0047] (3) Take 1000 μg / mL of sulfur standard solution and dilute it step by step to obtain sulfur calibration curve solution. The concentrations of sulfur calibration curve solution are: 0 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL, 20 μg / mL, and 25 μg / mL. Use inductively coupled plasma spectrometer to measure each solution to obtain a standard curve. Then use inductively coupled plasma spectrometer to measure the solution to be tested. The sulfur content of the solution to be tested is obtained by marking the curve. The sulfur content in the fingerprint-resistant liquid is calculated by the following formula:

[0048]

[0049] in:

[0050] c-the sulfur content of the solution to be tested, μg / mL;

[0051] V1 - volume of the solution to be tested, mL;

[0052] V0 - volume of anti-fingerprint liquid, mL;

[0053] S - sulfur content in the anti-fingerprint liquid, μg / mL.

[0054] In Example 2, 2 # The sulfur content of the anti-fingerprint liquid is 9.14μg / mL.

[0055] Take 2 # 12 mL of anti-fingerprint liquid was placed in a polytetrafluoroethylene beaker, and 1 mL of 100 μg / mL sulfur standard solution was added. The operation was carried out according to steps (1), (2), and (3). The value of the spiked sample was 2.093 μg / mL. The spiked recovery was calculated using the following formula:

[0056] Spiked recovery rate (%) = (spike sample measurement value - sample measurement value) ÷ spike amount × 100%

[0057] 2 # The recovery rate of the anti-fingerprint liquid spiked was 99.60%.

[0058] Example 3

[0059] (1) Take 3 # Put 15mL of fingerprint-resistant liquid into a polytetrafluoroethylene beaker, add 10mL of concentrated nitric acid and 10mL of concentrated hydrochloric acid, heat at 160℃ until the yellow smoke of the sample disappears and there is no more foam, add deionized water to the beaker to dilute the volume to 130mL, filter quickly with filter paper, transfer all the precipitate to the filter paper, rinse the original beaker and precipitate with deionized water 5 to 7 times, collect the filtrate and washing liquid in a clean beaker as the main liquid, and wrap the precipitate with filter paper;

[0060] (2) Place the precipitate wrapped with filter paper in a porcelain crucible, dry it, incinerate the filter paper, burn it in a high-temperature furnace at 750°C for 35 minutes, cool it, transfer the precipitate to the original polytetrafluoroethylene beaker, add 1mL of deionized water to moisten the precipitate, add 10mL of concentrated nitric acid and 10mL of hydrofluoric acid, heat to dissolve the precipitate, then add 7mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool it slightly, add 15mL of dilute hydrochloric acid prepared by concentrated hydrochloric acid and deionized water in a volume ratio of 1:1, heat to dissolve the salts, cool it, combine the solution with the main solution, heat to concentrate the volume, transfer it to a 100mL volumetric flask, dilute it, and make it up to volume to obtain the test solution;

[0061] (3) Take 1000 μg / mL of sulfur standard solution and dilute it step by step to obtain sulfur calibration curve solution. The concentrations of sulfur calibration curve solution are: 0 μg / mL, 1 μg / mL, 10 μg / mL, 20 μg / mL, 30 μg / mL, 40 μg / mL, respectively. Use inductively coupled plasma spectrometer to measure each solution to obtain a standard curve. Then use inductively coupled plasma spectrometer to measure the solution to be tested. The sulfur content of the solution to be tested is obtained by marking the curve. The sulfur content in the fingerprint-resistant liquid is calculated by the following formula:

[0062]

[0063] in:

[0064] c-the sulfur content of the solution to be tested, μg / mL;

[0065] V1 - volume of the solution to be tested, mL;

[0066] V0 - volume of anti-fingerprint liquid, mL;

[0067] S - sulfur content in the anti-fingerprint liquid, μg / mL.

[0068] In Example 3, 3 # The sulfur content of the anti-fingerprint liquid is 10.11μg / mL.

[0069] Take 3 #Place 15 mL of fingerprint-resistant liquid in a polytetrafluoroethylene beaker, add 1 mL of 100 μg / mL sulfur standard solution, and follow steps (1), (2), and (3). The value of the spiked sample is 2.520 μg / mL. Calculate the spiked recovery using the following formula:

[0070] Spiked recovery rate (%) = (spike sample measurement value - sample measurement value) ÷ spike amount × 100%

[0071] 3 # The recovery rate of the anti-fingerprint liquid spiked was 100.3%.

[0072] Example 4

[0073] (1) Take 4 # Put 15mL of anti-fingerprint liquid into a polytetrafluoroethylene beaker, add 12mL of concentrated nitric acid and 12mL of concentrated hydrochloric acid, heat at 200℃ until the yellow smoke of the sample disappears and there is no more foam, add deionized water to the beaker to dilute the volume to 130mL, filter quickly with filter paper, transfer all the precipitate to the filter paper, rinse the original beaker and precipitate with deionized water 5-7 times, collect the filtrate and washing liquid in a clean beaker as the main liquid, and wrap the precipitate with filter paper;

[0074] (2) Place the precipitate wrapped with filter paper in a porcelain crucible, dry it, incinerate the filter paper, burn it in a high-temperature furnace at 780°C for 40 minutes, cool it, transfer the precipitate to the original polytetrafluoroethylene beaker, add 2mL of deionized water to moisten the precipitate, add 12mL of concentrated nitric acid and 10mL of hydrofluoric acid, heat to dissolve the precipitate, then add 8mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool it slightly, add 15mL of dilute hydrochloric acid prepared by concentrated hydrochloric acid and deionized water in a volume ratio of 1:1, heat to dissolve the salts, cool it, combine the solution with the main solution, heat to concentrate the volume, transfer it to a 100mL volumetric flask, dilute, and make up to volume to obtain the test solution;

[0075] (3) Take 1000 μg / mL of sulfur standard solution and dilute it step by step to obtain sulfur calibration curve solution. The concentrations of sulfur calibration curve solution are: 0 μg / mL, 1 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL, 20 μg / mL, respectively. Use inductively coupled plasma spectrometer to measure each solution to obtain a standard curve. Then use inductively coupled plasma spectrometer to measure the solution to be tested. The sulfur content of the solution to be tested is obtained by annotating the curve. The sulfur content in the fingerprint-resistant liquid is calculated by the following formula:

[0076]

[0077] in:

[0078] c-the sulfur content of the solution to be tested, μg / mL;

[0079] V1 - volume of the solution to be tested, mL;

[0080] V0 - volume of anti-fingerprint liquid, mL;

[0081] S - sulfur content in the anti-fingerprint liquid, μg / mL.

[0082] In Example 4, 4 # The sulfur content of the anti-fingerprint liquid is 8.19 μg / mL;

[0083] (4) Take 4 # Place 15 mL of fingerprint-resistant liquid in a polytetrafluoroethylene beaker, add 1.0 mL of 100 μg / mL sulfur standard solution, and follow steps (1), (2), and (3). The value of the spiked sample is 2.225 μg / mL. Calculate the spiked recovery using the following formula:

[0084] Spiked recovery rate (%) = (spike sample measurement value - sample measurement value) ÷ spike amount × 100%

[0085] 4 # The recovery rate of the anti-fingerprint liquid spiked was 99.67%.

[0086] Example 5

[0087] (1) Take 5 # Put 20mL of anti-fingerprint liquid into a polytetrafluoroethylene beaker, add 15mL of concentrated nitric acid and 15mL of concentrated hydrochloric acid, heat at 200℃ until the yellow smoke of the sample disappears and there is no more foam, add deionized water to the beaker to dilute the volume to 150mL, filter quickly with filter paper, transfer all the precipitate to the filter paper, rinse the original beaker and precipitate with deionized water 5 to 7 times, collect the filtrate and washing liquid in a clean beaker as the main liquid, and wrap the precipitate with filter paper;

[0088] (2) Place the precipitate wrapped with filter paper in a porcelain crucible, dry it, incinerate the filter paper, burn it in a high-temperature furnace at 800°C for 50 min, cool it, transfer the precipitate to the original polytetrafluoroethylene beaker, add 2 mL of deionized water to moisten the precipitate, add 15 mL of concentrated nitric acid and 15 mL of hydrofluoric acid, heat to dissolve the precipitate, then add 10 mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool it slightly, add 15 mL of dilute hydrochloric acid prepared by a volume ratio of 1:1 with concentrated hydrochloric acid and deionized water, heat to dissolve the salts, cool it, combine the solution with the main solution, heat to concentrate the volume, transfer it to a 100 mL volumetric flask, dilute it, and make it up to volume to obtain the test solution;

[0089] (3) Take 1000 μg / mL of sulfur standard solution and dilute it step by step to obtain sulfur calibration curve solution. The concentrations of sulfur calibration curve solution are: 0 μg / mL, 5 μg / mL, 15 μg / mL, 25 μg / mL, 35 μg / mL, 50 μg / mL, respectively. Use inductively coupled plasma spectrometer to measure each solution to obtain a standard curve. Then use inductively coupled plasma spectrometer to measure the solution to be tested. The sulfur content of the solution to be tested is obtained by marking the curve. The sulfur content in the fingerprint-resistant liquid is calculated by the following formula:

[0090]

[0091] in:

[0092] c-the sulfur content of the solution to be tested, μg / mL;

[0093] V1 - volume of the solution to be tested, mL;

[0094] V0 - volume of anti-fingerprint liquid, mL;

[0095] S - sulfur content in the anti-fingerprint liquid, μg / mL.

[0096] In Example 5, 5 # The sulfur content of the anti-fingerprint liquid is 11.08μg / mL.

[0097] Take 5 # 20 mL of anti-fingerprint liquid was placed in a polytetrafluoroethylene beaker, and 2 mL of 100 μg / mL sulfur standard solution was added. The operation was carried out according to steps (1), (2), and (3). The value of the spiked sample was 4.22 μg / mL. The spiked recovery was calculated using the following formula:

[0098] Spiked recovery rate (%) = (spike sample measurement value - sample measurement value) ÷ spike amount × 100%

[0099] 5 # The recovery rate of the anti-fingerprint liquid spiked was 100.2%.

[0100] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the implementation methods. The protection scope of the present invention shall be subject to the scope defined in the claims. Other different forms of changes or modifications may be made based on the above description. Obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for detecting the sulfur content in anti-fingerprint liquid, characterized in that: The method comprises the following steps: (1) Weigh 10-20 mL of the original solution of the anti-fingerprint liquid and place it in a polytetrafluoroethylene beaker, add 7-15 mL of concentrated nitric acid and 7-15 mL of concentrated hydrochloric acid, heat the sample at 150-200° C. until the yellow smoke of the sample is gone and there is no more foam, add deionized water to dilute the volume to 100-150 mL, filter with filter paper, wash with deionized water, collect the precipitate and wrap it with filter paper, and collect the filtrate and washing liquid as the main liquid; (2) Place the precipitate wrapped with filter paper in a crucible, dry, incinerate the filter paper, calcine at 700-800°C for 30-50 min, cool, transfer the precipitate into a polytetrafluoroethylene beaker, add 1-2 mL of deionized water to moisten the precipitate, add 7-15 mL of concentrated nitric acid and 7-15 mL of hydrofluoric acid, heat to dissolve the precipitate, then add 5-10 mL of perchloric acid, continue heating until the perchloric acid smoke disappears, cool slightly, add 10-15 mL of dilute hydrochloric acid, heat to dissolve the salts, combine the solution with the main solution after cooling, heat to concentrate the volume, transfer to a 100 mL volumetric flask, dilute, and fix the volume to obtain a test solution; (3) preparing sulfur standard curve solutions with different concentration gradients, setting the working conditions of the inductively coupled plasma spectrometer, testing each solution to obtain a standard curve, and testing the test solution obtained in step (2) under the same working conditions to obtain the sulfur content detection value in the test solution, and calculating the sulfur content in the anti-fingerprint liquid stock solution.

2. The method for detecting sulfur content in anti-fingerprint liquid according to claim 1, characterized in that: In step (1), the precipitate is rinsed with deionized water 5 to 7 times.

3. The method for detecting sulfur content in anti-fingerprint liquid according to claim 1, characterized in that: In step (2), the dilute hydrochloric acid is prepared from concentrated hydrochloric acid and deionized water, and the volume ratio of concentrated hydrochloric acid to deionized water is 1:

1.

4. The method for detecting sulfur content in anti-fingerprint liquid according to claim 1, characterized in that: In step (2), the crucible is a porcelain crucible.

5. The method for detecting sulfur content in anti-fingerprint liquid according to claim 1, characterized in that: In step (3), the concentration range of the sulfur element standard curve solution is 0 to 50 μg / mL.

6. The method for detecting sulfur content in anti-fingerprint liquid according to claim 1, characterized in that: In step (3), the calculation formula is as follows: in: c-the sulfur content of the solution to be tested, μg / mL; V1 - volume of the solution to be tested, mL; V0 - volume of anti-fingerprint liquid, mL; S - sulfur content in the anti-fingerprint liquid, μg / mL.

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