Method for rapidly testing iodine and bromide ions in nylon polymer

Abstract

The invention relates to a method for rapidly testing iodine and bromide ions in a nylon polymer, which comprises the following steps: a pretreatment step: dissolving a nylon polymer to be tested in an acid solution to obtain a nylon solution, adding a precipitator into the nylon solution, extracting to obtain a supernatant containing elements to be tested, and collecting the supernatant; diluting the supernate with a diluent to obtain a solution to be detected; and a determination step: determining the content of iodine and bromide ions in the solution to be determined through an inductively coupled plasma mass spectrometer. By adopting the testing method disclosed by the invention, the recovery rate of iodine and bromine reaches 95-105%; the method is simple in operation, wide in quantification range and high in universality, the addition amount of iodine and bromine in a conventional nylon polymer is 40-2000 [mu] g / g, accurate quantification can be achieved, and detection of trace iodine and bromine elements in the nylon polymer can be achieved; pretreatment equipment is simple, and an expensive pretreatment device is not needed.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to a rapid testing method for iodine and bromide ions in nylon polymers. Background Art

[0002] For the detection and analysis of non-metallic elements such as bromine and iodine, commonly used determination methods include titration, spectrophotometry, ion chromatography (IC) or inductively coupled plasma mass spectrometry (ICP-MS). Among them, the determination steps of titration and spectrophotometry are cumbersome, the chemical reactions are complex and easily interfered with, and the accuracy is poor; although ion chromatography can analyze multiple non-metallic elements at the same time, it takes a long time to determine a sample, and sometimes multiple elements cannot be analyzed at the same time; inductively coupled plasma mass spectrometry is a rapid detection technology that has developed rapidly in recent years. It has high sensitivity, relatively small interference between elements, and can determine multiple elements at the same time.

[0003] However, the detection of bromine and iodine in nylon polymers cannot be used directly for detection. The test samples need to be pre-treated before their element content can be analyzed and determined. The current sample pre-treatment methods mainly include: (1) combustion method, carbonizing or burning the compound at high temperature, and extracting the element to be tested in the compound with a suitable absorption liquid; (2) acid digestion method, using a strong oxidizing acid substance to fully oxidize or destroy the polymer structure, and extracting the element to be tested after obtaining the digestion solution; (3) solvent extraction method, selecting a suitable extraction solvent to directly extract the element to be tested from the sample. Among the above pre-treatment methods, the combustion method and the acid digestion method both involve high temperature or strong acid, and the iodine and bromine elements are very easy to turn into volatile substances such as iodine element, bromine element, hydrogen iodide, and hydrogen bromide, resulting in the loss of the element to be tested and a low recovery rate; while the amount of iodine and bromine added in nylon polymers is small, and they are compatible with polymers. Conventional extraction solvents and extraction equipment cannot achieve complete extraction of iodine and bromine elements, and usually need to be matched with expensive microwave extractors, and microwave extraction also takes a long time. Summary of the invention

[0004] Technical problem: The purpose of the present invention is to overcome the shortcomings of the prior art and provide a rapid test method for iodine and bromide ions in nylon polymers. The method has a wide quantitative range and strong universality. The amount of iodine and bromine added in conventional nylon polymers is 40-2000ug / g, and accurate quantification can be achieved, and trace iodine and bromine elements in nylon polymers can be detected; the pretreatment equipment is simple and no expensive pretreatment device is required.

[0005] Technical solution: The present invention provides a rapid testing method for iodine and bromide ions in nylon polymers, the testing method comprising the following steps:

[0006] Pretreatment step: dissolving the nylon polymer to be tested in an acid solution to obtain a nylon solution, adding a precipitant to the nylon solution, extracting to obtain a supernatant containing the element to be tested, and diluting the supernatant with a diluent to obtain a solution to be tested;

[0007] Determination steps: The solution to be tested is measured by inductively coupled plasma mass spectrometry to determine the content of iodine and bromide ions.

[0008] in,

[0009] In the pretreatment step: the acidity of the acid solution is greater than or equal to formic acid, and the oxidizing power is less than or equal to formic acid.

[0010] In the pre-treatment step: the acid solution includes one or more of formic acid, hydrofluoric acid and hydrochloric acid.

[0011] In the pre-treatment step, the precipitant includes water.

[0012] In the pre-treatment step, the amount of acid solution added can fully dissolve the nylon polymer.

[0013] In the pre-treatment step, the extraction uses ultrasonic treatment to treat the nylon solution to remove the precipitate to obtain the supernatant containing the element to be tested.

[0014] In the pre-treatment step, the diluent includes dilute ammonia water.

[0015] In the pre-treatment step, the mass concentration of the dilute ammonia water is 1-5%.

[0016] In the pre-treatment step, the supernatant is diluted with a diluent, and the dilution multiple is between 10-50 times; the pH of the solution to be tested is greater than or equal to 8.

[0017] In the determination step, the content of I and Br in the solution to be tested is determined by an external standard method or an internal standard method.

[0018] Beneficial effects: The present invention uses a weakly oxidizing acid solution to dissolve the nylon polymer, which can effectively reduce the volatilization of bromine and iodine, and then uses a precipitant to further extract to obtain a supernatant containing the element to be tested, and uses dilute ammonia water to dilute the supernatant, and then uses ICP-MS (inductively coupled plasma mass spectrometer) to determine the iodine and bromine elements therein, wherein the detection limits of iodine and bromine can reach 1.8ug / g and 2.2ug / g. The test method of the present invention uses an iodine and bromine recovery rate of 95-105%; the quantitative range is wide, the method has strong universality, and the amount of iodine and bromine added in conventional nylon polymers is 40-2000ug / g, which can achieve accurate quantification, and can detect trace iodine and bromine elements in nylon polymers; the pretreatment equipment is simple, and no expensive pretreatment device is required. DETAILED DESCRIPTION

[0019] The present invention provides a rapid testing method for iodine and bromide ions in nylon polymers, the testing method comprising the following steps:

[0020] Pretreatment step: dissolving the nylon polymer to be tested in an acid solution to obtain a nylon solution, adding a precipitant to the nylon solution, extracting to obtain a supernatant containing the element to be tested, and diluting the supernatant with a diluent to obtain a solution to be tested;

[0021] Determination steps: The solution to be tested is measured by inductively coupled plasma mass spectrometry to determine the content of iodine and bromide ions.

[0022] In the pre-treatment steps:

[0023] The acidic property of the acid solution is greater than or equal to formic acid, and the oxidizing property is less than or equal to formic acid;

[0024] Furthermore, the acid solution includes one or more of formic acid, hydrofluoric acid, and hydrochloric acid;

[0025] In some embodiments of the present invention, the pH value of the acid solution is 1-3, preferably 1-2;

[0026] The precipitant includes water;

[0027] The amount of acid added can fully dissolve the nylon polymer;

[0028] As an example, the mass of nylon polymer is 50-200 mg, the volume of acid solution is 5-10 mL, and the volume of precipitant is 50-100 mL;

[0029] Furthermore, the extraction can be performed by ultrasonically treating the nylon solution to remove the precipitate to obtain the supernatant containing the element to be detected;

[0030] In some embodiments of the present invention, the ultrasonic treatment time is controlled according to the precipitation situation, and the ultrasonic treatment time is 10 to 60 minutes;

[0031] Furthermore, the precipitate can be removed by centrifugation or static method. Preferably, the centrifugation method can be used to shorten the time.

[0032] The diluent includes dilute ammonia water;

[0033] The mass concentration of the dilute ammonia water is 1-5%, wherein the dilute ammonia water can reduce the memory effect of elements such as iodine and bromine.

[0034] The dilution multiple is between 10-50 times; the pH of the solution to be tested is greater than or equal to 8.

[0035] In the determination steps:

[0036] The content of I and Br in the test solution can be determined by external standard method or internal standard method.

[0037] In some examples of the present invention, the internal standard curve method is used to quantitatively analyze I and Br in the test solution.

[0038] Preferably, the test mode can be selected and the instrument can be optimized and calibrated according to the brand and model of the inductively coupled plasma mass spectrometer used.

[0039] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0040] Example:

[0041] Pretreatment step: dissolving 50-200 mg of the nylon polymer to be tested in 5-10 mL of acid solution to obtain a nylon solution, adding 100 mL of a precipitant to the nylon solution, ultrasonically treating for 15 minutes, centrifuging to remove the supernatant containing the element to be tested, diluting the supernatant with a diluent to obtain a solution to be tested, and controlling the pH value of the solution to be tested to 8.5.

[0042] Determination steps: The solution to be tested is passed through an inductively coupled plasma mass spectrometer, and the contents of I and Br in the solution to be tested are determined using an internal standard curve method in collision mode.

[0043] In the examples and comparative examples of the present invention, the inductively coupled plasma mass spectrometer used is Perkin-Elmer NEXION 350X ICP-MS.

[0044] The instrument was optimized and calibrated before determination: 1ug / L Be, Ce, and In tuning solutions were used to optimize to Be>2000cps, In>40000cps, Ce++ / Ce≤0.03, and CeO / Ce≤0.25; germanium and indium were used as internal standards for iodine and bromine, respectively, and inert gas was used as collision gas; the collision gas flow rates of iodine and bromine were 4-6mL / min and 2-4mL / min, respectively.

[0045] Determination of standard curve:

[0046] Take 1000ug / ml bromine and iodine single standard solution standards (prepared with potassium bromide and potassium iodide respectively), prepare them into 1ug / ml mixed standard substance solution, and use dilute ammonia solution with a mass fraction of 4-20g / mL to dilute them into mixed standard solutions of bromine and iodine according to a concentration gradient, with concentrations of 0, 5, 10, 20, 50, 100, 200, and 500ug / L.

[0047] The test method of the embodiment is as follows:

[0048]

[0049] Comparative Example 1

[0050] The difference from the embodiment is that no diluent is added for dilution in the pretreatment step, and the determination step is directly performed, and the other steps remain unchanged.

[0051] Comparative Example 2

[0052] The difference from the embodiment is that the pre-treatment step uses 1% HNO3 diluent to replace the original ammonia water, and the rest remains unchanged.

[0053] Comparative Example 3

[0054] The difference from Example 1 is that the pretreatment step adopts the acid digestion method. After 100 mg of the nylon polymer to be tested is microwave-digested with 6 mL of concentrated nitric acid, the volume is fixed to 50 ml with ultrapure water, and then diluted to pH 8.5 with dilute ammonia water, and the measurement step is carried out. The measurement step is consistent with Example 1.

[0055] Comparative Example 4

[0056] The difference from Example 1 is that the pretreatment step adopts solvent extraction method, 100 mg of nylon polymer to be tested is added to 50 ml of 10% formic acid solution for ultrasonic extraction for 1 hour, and then diluted with dilute ammonia water to pH 8.5, and the measurement step is carried out. The measurement step is consistent with Example 1.

[0057] The above Examples 1-7 and Comparative Examples 1-4 were used to test the iodine and bromine contents of the nylon polymer to be tested. The test results are as follows:

[0058]

[0059] The iodine and bromine contents of different nylon polymers were tested using the test method of Example 1. The test results are as follows:

[0060]

[0061]

[0062] It can be seen from the above performance test results that the test method of the present invention can be used to simply and quickly detect bromine and iodine in nylon polymerization without the need for strong oxidizing acid treatment or long-term extraction. The measurement accuracy of the embodiment of the present application is much higher than the acid digestion method and solvent extraction method of Comparative Examples 2 and 3, and the bromine and iodine content measurement range is wide, and the iodine and bromine contents in the range of 40-2000ug / g can be accurately quantified.

Claims

1. A rapid test method for iodine and bromide ions in nylon polymers, characterized in that: The testing method comprises the following steps: Pretreatment step: dissolving the nylon polymer to be tested in an acid solution to obtain a nylon solution, adding a precipitant to the nylon solution, extracting to obtain a supernatant containing the element to be tested, and diluting the supernatant with a diluent to obtain a solution to be tested; Determination steps: The solution to be tested is measured by inductively coupled plasma mass spectrometry to determine the content of iodine and bromide ions.

2. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pretreatment step: the acidity of the acid solution is greater than or equal to formic acid, and the oxidizing power is less than or equal to formic acid.

3. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step: the acid solution includes one or more of formic acid, hydrofluoric acid and hydrochloric acid.

4. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step, the precipitant includes water.

5. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step, the amount of acid solution added can fully dissolve the nylon polymer.

6. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step, the extraction uses ultrasonic treatment to treat the nylon solution to remove the precipitate to obtain the supernatant containing the element to be tested.

7. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step, the diluent includes dilute ammonia water.

8. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step, the mass concentration of the dilute ammonia water is 1-5%.

9. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the pre-treatment step, the supernatant is diluted with a diluent, and the dilution multiple is between 10-50 times; the pH of the solution to be tested is greater than or equal to 8.

10. The rapid testing method for iodine and bromide ions in nylon polymer according to claim 1, characterized in that: In the determination step, the content of I and Br in the solution to be tested is determined by an external standard method or an internal standard method.

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