阅读说明：本技术 一种水溶性荧光增白剂的荧光增强方法 (Fluorescence enhancement method of water-soluble fluorescent whitening agent ) 是由 沈晓芳 赵翔宇 庞月红 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种水溶性荧光增白剂的荧光增强方法,属于化工及分析检测技术领域。本发明首次发现了离子对试剂对荧光增白剂的荧光增强作用,旨在减少荧光增白剂的使用量而达到相同的增白效果,降低荧光增白剂对环境的影响,减少其在食物链中的积累；可用于水溶性荧光增白剂的检测,使得检测方法的检测速度快,线性关系良好,灵敏度高,其中决定系数R<Sup>2</Sup>在0.9991-0.9998之间,检出限(LOD)为0.43-1.19ng/mL,定量限(LOQ)为1.44-3.97ng/mL；同时,应用于实际样品的检测时,获得了良好的回收率,均达83.44％以上。本发明不仅拓展了离子对试剂的应用领域,减少荧光增白剂的使用,可以降低成本,对环境友好,操作简便,检测成本低,是一种便捷方便、绿色环保的检测方法。(The invention discloses a fluorescence enhancement method of a water-soluble fluorescent whitening agent, belonging to the technical field of chemical engineering and analysis and detection. The invention discovers the fluorescence enhancement effect of the ion pair reagent on the fluorescent whitening agent for the first time, and aims to reduce the using amount of the fluorescent whitening agent to achieve the same whitening effect, reduce the influence of the fluorescent whitening agent on the environment and reduce the accumulation of the fluorescent whitening agent in a food chain; can be used for detecting water-soluble fluorescent whitening agent, and has the advantages of high detection speed, good linear relation, high sensitivity, and determination coefficient R 2 Between 0.9991 and 0.9998, the detection Limit (LOD) is 0.43 to 1.19ng/mL, and the quantification Limit (LOQ) is 1.44 to 3.97 ng/mL; meanwhile, when the method is applied to detection of actual samples, good recovery rates are obtained, and the recovery rates are all more than 83.44%. The invention not only expands the application field of the ion pair reagent, reduces the use of fluorescent whitening agent, can reduce cost, is environment-friendly, simple and convenient to operate and low in detection cost, and is a convenient, green and environment-friendly detection method.)

1. A method for enhancing the fluorescence intensity of a water-soluble fluorescent whitening agent is characterized in that an ion-pairing reagent is added into a water-soluble fluorescent whitening agent sample, and the fluorescence intensity emitted by the fluorescent whitening agent can be enhanced after the mixture is mixed and reacted completely.

2. The pretreatment method according to claim 1, wherein the ion-pairing reagent comprises any one or more of tetrabutylammonium bromide, tetraethylammonium bromide and tetrabutylammonium hydrogen sulfate.

3. A process according to claim 1 or 2, characterized in that the water-soluble fluorescent whitening agent is of the diphenylethylene type.

4. A process according to any one of claims 1 to 3, characterized in that the representative water-soluble fluorescent whitening agent is any one of fluorescent whitening agent 113, fluorescent whitening agent 220, fluorescent whitening agent 71, fluorescent whitening agent 85.

5. The method according to any one of claims 1 to 4, further comprising adjusting the pH of the water-soluble fluorescent whitening agent and ion pair system to from 2 to 12.

6. The method according to any one of claims 1 to 5, wherein alkali metal salts are further added, wherein the alkali metal salts comprise sodium salts, potassium salts; the salt includes hydrochloride, sulfate, nitrate.

7. The process according to any one of claims 1 to 6, wherein the reaction time is from 0 to 5 min.

8. A method for detecting fluorescent whitening agent, wherein a sample of fluorescent whitening agent is treated by the method of any one of claims 1 to 7 to obtain a solution to be detected; then the sample is placed in a fluorescence spectrophotometer for detection.

9. The method according to claim 8, characterized in that it comprises the steps of:

(1) determination of the standard curve: preparing a standard solution to be tested of the fluorescent whitening agent with known concentration by using the method of any one of claims 1 to 7, and placing the standard solution in a fluorescence spectrophotometer to measure the fluorescence intensity; establishing a standard curve through the concentration and the fluorescence intensity of the standard solution to be detected;

(2) and (3) determination of a sample to be tested: preparing a solution to be tested of a sample to be tested by using the method of any one of claims 1 to 7, measuring the fluorescence intensity by using a fluorescence spectrophotometer, and then obtaining the content of the fluorescent whitening agent in the sample to be tested by using the standard curve obtained in the step (1).

10. A method for detecting the content of fluorescent whitening agent in food packaging, characterized in that it comprises the following steps:

(1) packaging and chopping food, adding water for mixing, shaking, and filtering to obtain an aqueous solution sample;

(2) the method according to any one of claims 1 to 7, wherein an ion-pair reagent is added to the aqueous solution sample to prepare a solution to be measured, and the fluorescence intensity is measured by a fluorescence spectrophotometer;

(3) using the calibration curve according to claim 9, the content of fluorescent whitening agent in the food packaging is obtained.

Technical Field

The invention relates to a fluorescence enhancement method of a water-soluble fluorescent whitening agent, belonging to the technical field of chemical engineering and analysis and detection.

Background

Fluorescent Whitening Agents (FWAs) are industrial organic dyes with complex chemical structures that absorb ultraviolet light (290- & ltSUB & gt 400nm) and emit visible blue light (400- & ltSUB & gt 480nm) to enhance the whiteness and brightness of objects, and thus are widely used in the textile, paper, household detergents, and plastic industries. In order to reduce costs, some undesirable merchants have added optical brighteners to food packaging in recent years in order to increase the whiteness and brightness of the packaging.

Fluorescent whitening agents have a stable chemical structure and are difficult to metabolize out after entering the human body, and are likely to accumulate in the human body for a long time, thereby injuring important organs of the human body. Fluorescent whitening agents have been reported to be at risk of carcinogenesis and have been tested to have a damaging effect on zebrafish embryos. The fluorescent whitening agents in food packaging can enter the human body by direct contact or by migration into the food and thus into the human body, potentially causing harm to the human body. Many countries, including china, the united states and the european union, have clear restrictions on the use of optical brighteners in food packaging, requiring that chemical dyes such as optical brighteners cannot be used in food packaging. Therefore, it is important to establish a simple and effective detection method for detecting the fluorescent whitening agent in the food package.

The existing detection methods for the fluorescent whitening agent include a whiteness method, an ultraviolet lamp irradiation observation method, an ultraviolet spectrophotometry method, a fluorescence spectrophotometry method, a high performance liquid chromatography and a liquid chromatography-tandem mass spectrometry. Although the ultraviolet lamp irradiation method is simple and rapid to operate and low in technical requirement, the detection precision is poor, the detection method is easy to be interfered by the outside, and large subjective factors exist. Uv spectrophotometry, although quantitative, is relatively insensitive and cannot detect traces of fluorescent whitening agent migrating into food. Although the high performance liquid chromatography can carry out quantitative detection on the fluorescent whitening agent, the operation process is complex, needs professional personnel to operate, and is time-consuming and labor-consuming. Meanwhile, most of fluorescent whitening agents in food paper packaging are water-soluble, most of the current research objects of liquid chromatography are fat-soluble fluorescent whitening agents, and a detection method for water-soluble fluorescent whitening agents in food paper packaging needs to be developed.

Meanwhile, the water-soluble fluorescent whitening agent is widely applied to the detergent industry, the fluorescent whitening agent is widely applied in Europe and America, and 40% of the world fluorescent whitening agent output is applied to the detergent industry according to incomplete statistics. Some products of the known laundry detergent brand in europe and the usa incorporate fluorescent whitening agents. The relative dosage of the fluorescent whitening agent in the detergent is small and is only equivalent to 0.1-0.5 percent of the mass of the detergent. The fluorescent brightener for the detergent is classified into distyryl biphenyl and bistriazinyl amino stilbene according to QB/T2953-2008 fluorescent brightener for the detergent in the light industry standard of China. The standard specifies sensory indexes (smell, appearance) and physical and chemical indexes (ultraviolet absorption value, solubility, moisture, volatile matter, and water-insoluble substance).

The fluorescent whitening agent is a substance with a relatively stable chemical structure, so that the fluorescent whitening agent is not easy to decompose and is easy to cause certain harm to water and soil environment. We find that the ion pair agent can effectively enhance the fluorescence intensity of the fluorescent whitening agent, thereby reducing the use amount of the fluorescent whitening agent, achieving the same whitening effect and reducing the harm of the fluorescent whitening agent to the ecological environment; meanwhile, for trace fluorescent whitening agent contained in food package, ion pair reagent can be used for fluorescence enhancement, a new fluorescent whitening agent detection method is established, and rapid, convenient and high-sensitivity detection is realized.

Disclosure of Invention

Aiming at the problems, the method for detecting the fluorescent whitening agent in the food paper package is established by utilizing an ion-pairing reagent to enhance the fluorescence of the fluorescent whitening agent in an aqueous matrix and combining a fluorescence spectrophotometry method. The effectiveness and accuracy of the method are verified by optimizing the detection conditions and the detection of actual samples. Compared with the previously reported method, the method is simple to operate, reduces the detection limit of the previous fluorescence spectrophotometry, expands the application field of the ion pair reagent, has important significance for detecting the trace fluorescent whitening agent in food packaging, and provides a new idea for detecting the fluorescent whitening agent.

The first purpose of the invention is to provide a method for enhancing fluorescent intensity of a fluorescent whitening agent, which comprises the steps of adding an ion-pairing reagent into an aqueous solution of a fluorescent whitening agent sample, and obtaining a fluorescent whitening agent sample after complete mixing and reaction.

In one embodiment of the invention, the method further comprises adjusting the pH of the sample to be tested to 2 to 12.

In one embodiment of the invention, the fluorescent whitening agent is a water-soluble stilbene-type fluorescent whitening agent; including any one or more of fluorescent brightener 113(FWA 113), fluorescent brightener 220(FWA 220), fluorescent brightener 71(FWA 71), and fluorescent brightener 85(FWA 85).

In one embodiment of the invention, the ion-pair reagent comprises all kinds of ion pairs, such as tetrabutylammonium bromide (TBAB), tetraethylammonium bromide (TEAB), tetrabutylammonium hydrogen sulfate (TBA-HS). Tetrabutylammonium bromide (TBAB) is preferred.

The second purpose of the invention is to provide a method for detecting fluorescent whitening agent based on ion-pair reagent fluorescence enhancement method combined with fluorescence spectrophotometer, wherein the method comprises the steps of treating a fluorescent whitening agent sample by using the pretreatment method to obtain a solution to be detected; then the sample is placed in a fluorescence spectrophotometer for detection.

In one embodiment of the invention, the method comprises the steps of:

(1) determination of the standard curve: preparing standard solution to be detected of the fluorescent whitening agent with known concentration by the pretreatment method, and placing the standard solution to be detected in a fluorescence spectrophotometer to detect fluorescence intensity; establishing a standard curve through the concentration and the fluorescence intensity of the standard solution to be detected;

(2) and (3) determination of a sample to be tested: and (2) preparing a to-be-detected liquid of the to-be-detected sample by using the pretreatment method, measuring the fluorescence intensity by using a fluorescence spectrophotometer, and then obtaining the content of the fluorescent whitening agent in the to-be-detected sample by using the standard curve obtained in the step (1).

A third object of the present invention is to provide a method for detecting the content of fluorescent whitening agent in food packaging, comprising the steps of:

(1) packaging and chopping food, adding water for mixing, shaking, and filtering to obtain an aqueous solution sample;

(2) adding an ion pair reagent into the aqueous solution sample to prepare a solution to be detected, and measuring the fluorescence intensity by a fluorescence spectrophotometer;

(3) the content of the fluorescent whitening agent in the food packaging is obtained by using the standard curve.

In one embodiment of the invention, the food package is paper food package of all kinds on the market, including instant noodle barrel, paper cup, paper bowl, popcorn barrel, etc.

Has the advantages that:

the invention discovers the fluorescence enhancement effect of the ion pair reagent on the fluorescent whitening agent for the first time, different ion pair reagents have different fluorescence enhancement effects on different fluorescent whitening agents, the maximum enhancement multiple can reach 5-6 times, and the ion pair reagent has obvious enhancement effect. Compared with the traditional analysis method, the method has the advantages of high detection speed, good linear relation and high sensitivity, wherein the coefficient R is determined²Between 0.9991 and 0.9998, the detection Limit (LOD) is 0.43 to 1.19ng/mL, and the quantification Limit (LOQ) is 1.44 to 3.97 ng/mL; tests prove that the method has effectiveness and accuracy, and is applied to the detection of actual samples to obtain good recovery rates which are all more than 83.44%.

The method reduces the use amount of the fluorescent whitening agent to a certain extent, reduces the influence of the fluorescent whitening agent on the environment, does not need complex pretreatment, has low detection cost, is a convenient, convenient and environment-friendly detection method, expands the application field of ions to reagents, and provides a new idea for the detection of the fluorescent whitening agent.

Drawings

FIG. 1 shows the result of enhancement of the fluorescence intensity of fluorescent whitening agent 85;

FIG. 2 shows the result of enhancement of the fluorescence intensity of the fluorescent whitening agent 113;

FIG. 3 shows the result of the enhancement of the fluorescence intensity of the fluorescent whitening agent 220;

FIG. 4 is a graph showing the effect of pH on the fluorescent effect of optical brighteners 85, 113 and 220;

FIG. 5 shows the effect of the concentration of the ion pairing agent on the fluorescent effect of fluorescent whitening agent 85, fluorescent whitening agent 113 and fluorescent whitening agent 220.

Detailed Description

Exemplified according to what is contained in the claims.