Rapid detection method and kit for anion synthetic detergent in recyclable tableware

Abstract

The invention relates to a rapid detection method and kit for an anionic synthetic detergent in recyclable tableware, and the detection method comprises the following steps: washing the tableware with pure water, and collecting a washing solution; taking the washing liquid, sequentially adding a color developing agent solution and ethyl acetate into the washing liquid, uniformly shaking, and standing for a period of time; and sucking supernatant liquid, comparing the supernatant liquid with a standard colorimetric card in color, and calculating the concentration of the anionic synthetic detergent in the washing liquid according to the color gradation of the standard colorimetric card. The detection method provided by the invention has the advantages of simple pretreatment operation and convenient detection, and is suitable for rapid detection requirements; and 2) the lowest detection mass concentration of the detection method provided by the invention is 0.030 mg / L, which is lower than 0.050 mg / L required by the limit of GB 14934-2016, and the detection method has higher sensitivity and can completely meet the requirement of limited supervision on the anion synthetic detergent.

Description

Technical Field

[0001] The invention relates to the field of chemical detection, and in particular to a method and a kit for rapid detection of anionic synthetic detergents in reusable tableware. Background Art

[0002] Anionic synthetic detergents are the main active ingredients of washing powder, laundry detergent, and dishwashing liquid. The use of such products in daily life will produce anionic surfactant wastewater. Anionic surfactants have the advantages of being easy to use, easy to dissolve, stable, and low cost. They are widely used in the cleaning of tableware in hotels, restaurants, canteens, etc. Anionic synthetic detergents are toxic to a certain extent. If the tableware is not fully rinsed during cleaning, detergents will remain on the tableware and accumulate in the human body through food, endangering human health. It may also cause acute poisoning in people, and the main manifestations of poisoning are symptoms of the central nervous system and gastrointestinal tract. Therefore, my country has formulated GB 14934-2016 "National Food Safety Standard for Disinfection of Tableware (Drinking)", which stipulates that the residual amount of anionic synthetic detergents in tableware (drinking) disinfected by chemical disinfection should not be detected. The regulatory departments at all levels of the state, provinces, and cities have included the residual anionic synthetic detergents in tableware in the sampling monitoring items.

[0003] At present, the main methods for detecting anionic synthetic detergents are spectrophotometry and flow injection method. Spectrophotometry methods include: methylene blue spectrophotometry, phenanthroline extraction spectrophotometry, and the principle of spectrophotometry is to use positively charged ion complexes to react with negatively charged anionic synthetic detergents to form complexes that are insoluble in water but soluble in organic solvents, and then extract with chloroform to quantitatively determine the content of anionic synthetic detergents in the sample by measuring the absorbance value according to the depth of color in the organic layer. Flow injection method uses a continuous flow instrument for continuous online detection, which saves manpower and improves efficiency. All of the above methods can accurately quantify, but the required instruments are expensive, time-consuming, and the detection steps are complicated, which is not conducive to rapid on-site detection. Summary of the invention

[0004] In view of the problems of complicated detection steps and inability to separate the organic layer in the current standard test methods, this paper provides a simple-to-operate, highly sensitive and rapid detection method and kit for anionic synthetic detergents in reusable tableware, which can provide certain technical support for the supervision of anionic synthetic detergents in tableware.

[0005] The specific technical solutions are as follows:

[0006] The first aspect of the present invention is to provide a rapid detection method for anionic synthetic detergents in reusable tableware, comprising:

[0007] Wash tableware with pure water and collect the washing liquid;

[0008] Take the washing liquid, add the developer solution and ethyl acetate to it in sequence, shake well and let it stand for a while;

[0009] Aspirate the upper clear liquid, compare the color with the standard colorimetric card, and calculate the concentration of anionic synthetic detergent in the washing liquid according to the color depth of the standard colorimetric card;

[0010] The color developer is one of rhodamine B, safranin T, rhodamine 6G, and ethyl violet.

[0011] Furthermore, when washing, the surface area of ​​tableware in contact with food is calculated as per 1cm 2 The contact area was washed with 1 mL of pure water.

[0012] Furthermore, the volume of the washing solution is not less than 20 mL, the volume of the developer solution is 0.5-3.0 mL, and the volume of ethyl acetate is 4-8 mL.

[0013] Furthermore, the concentration of the developer solution is 20-70 mg / L.

[0014] Further, the preparation method of the standard colorimetric card is:

[0015] Prepare a standard solution of sodium dodecylbenzene sulfonate with gradient concentrations;

[0016] Add the color developer solution and ethyl acetate to the sodium dodecylbenzene sulfonate standard solution in sequence, shake well and let stand for a while;

[0017] The upper clear liquid is aspirated to prepare standard color scale solutions, and standard color comparison cards are printed according to the color values ​​of each standard color scale solution.

[0018] Further, the concentrations of the sodium dodecylbenzene sulfonate standard solutions are 0.00 mg / L, 0.010 mg / L, 0.020 mg / L, 0.030 mg / L, 0.040 mg / L, 0.050 mg / L, 0.10 mg / L, 0.20 mg / L, 0.40 mg / L, 0.50 mg / L, 1.0 mg / L, and 2.0 mg / L. 。

[0019] Furthermore, the volume of the sodium dodecylbenzenesulfonate standard solution is not less than 20 mL, the volume of the developer solution is 0.5-3.0 mL, and the volume of ethyl acetate is 4-8 mL.

[0020] Furthermore, the concentration of the developer solution is 20-70 mg / L.

[0021] The second aspect of the present invention is to provide a rapid detection kit for anionic synthetic detergents in reusable tableware, comprising a washing solution, an extracting solution, and a color developer solution; wherein the washing solution is pure water, the extracting solution is ethyl acetate, and the color developer is one of rhodamine B, safranin T, rhodamine 6G, and ethyl violet.

[0022] Furthermore, the kit also includes an area measuring device, which is a ruler-type tool, including but not limited to a folding ruler, a ruler or a vernier caliper and other conventional tools that can calculate or read the area.

[0023] In the present invention, sodium dodecylbenzene sulfonate (SDBS), a main component of anionic synthetic detergent, reacts with a color developer to form an organic dye with obvious color and high recognizability, and then the organic dye is extracted with an organic solvent to form a system with different color depths, which is then compared with a standard colorimetric card to determine the residual amount of anionic synthetic detergent in tableware.

[0024] Considering that ethyl acetate has a lower density than water, is slightly soluble in water, and has low toxicity, it can easily meet market regulatory requirements. Therefore, ethyl acetate is selected as the extraction solvent in the present invention. The selection and use of the above extraction solvent allows the upper clear liquid to be quickly separated using only a rubber-tipped dropper, thereby further meeting the needs of rapid detection.

[0025] The beneficial effects of the above scheme are:

[0026] 1) The detection method provided by the present invention has simple and efficient pre-treatment operation, convenient and fast detection, and is suitable for rapid detection needs;

[0027] 2) The minimum detection mass concentration of the detection method provided by the present invention is 0.030 mg / L, which is lower than the limit requirement of 0.050 mg / L in GB 14934-2016. It has higher sensitivity and can fully meet the requirements for the limit regulation of anionic synthetic detergents. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The color diagram of each sodium dodecylbenzene sulfonate standard solution when the rapid detection method provided by the present invention is used for detection in Example 1;

[0029] Figure 2 The color diagram of each sodium dodecylbenzene sulfonate standard solution when the rapid detection method provided by the present invention is used for detection in Example 2;

[0030] Figure 3 The color diagram of each sodium dodecylbenzene sulfonate standard solution when the rapid detection method provided by the present invention is used for detection in Example 3;

[0031] Figure 4This is a color diagram of each sodium dodecylbenzene sulfonate standard solution when the rapid detection method provided by the present invention is used for detection in Example 4. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0035] Example 1

[0036] This embodiment provides a method for rapid detection of anionic synthetic detergents in reusable tableware, comprising:

[0037] Use a vernier caliper to calculate the surface area of ​​tableware in contact with food, and then take samples according to the sampling method specified in GB 14934-2016 National Food Safety Standard for Disinfected Tableware (Drinking Utensils), that is, take samples every 100cm 2 Wash the tableware with pure water at a ratio of 100 mL of pure water to the contact surface area, and collect the washing liquid; use a measuring cylinder to measure 40 mL of washing liquid, add 2 mL and 60 mg / L rhodamine B solution and 7 mL of ethyl acetate (analytical grade) thereto in sequence, shake well and let stand for 1 min; use a rubber-tipped dropper to draw the upper clear liquid into a 5 mL centrifuge tube, compare the color with the standard colorimetric card, and calculate the concentration of anionic synthetic detergent in the washing liquid according to the color depth of the standard colorimetric card.

[0038] The preparation method of the standard colorimetric card of the present invention is as follows: prepare a sodium dodecylbenzene sulfonate standard solution with gradient concentrations of 0.00 mg / L, 0.010 mg / L, 0.020 mg / L, 0.030 mg / L, 0.040 mg / L, 0.050 mg / L, 0.10 mg / L, 0.20 mg / L, 0.40 mg / L, 0.50 mg / L, 1.0 mg / L and 2.0 mg / L respectively; use a measuring cylinder to measure 20 mL of the sodium dodecylbenzene sulfonate standard solution, add 2 mL and 60 mg / L of rhodamine B solution and 7 mL of ethyl acetate (analytical grade) respectively thereto, shake well and let stand for 1 minute; use a rubber-tipped dropper to absorb the upper clear liquid to obtain a standard color scale solution (such as Figure 1As shown), a standard colorimetric card is printed according to the color value of each standard color scale solution.

[0039] In the present invention, sodium dodecylbenzene sulfonate standard is taken and prepared with pure water to form sodium dodecylbenzene sulfonate standard solutions with concentrations of 0 mg / L, 0.010 mg / L, 0.020 mg / L, 0.030 mg / L, 0.040 mg / L, and 0.050 mg / L, respectively. The detection is carried out according to the above method, and the blank sample is used as a reference to observe whether the color of each sample can be recognized by the naked eye. Observation shows that the blank sample is colorless and transparent, and samples at concentrations of 0.030 mg / L and above have obvious visible red. It can be seen from the conversion that the detection limit of the method provided by the present invention is 0.0030 mg / 100 cm 2 .

[0040] In order to verify whether the rapid detection method provided by the present invention is consistent with the results measured by the national standards, industry standards or verified normative methods involved in the corresponding project (GB 14934-2016 "National Food Safety Standard for Disinfection of Tableware (Drinking Utensils") stipulates that anionic synthetic detergents (calculated as sodium dodecylbenzene sulfonate) in tableware shall not be detected), the present invention selects 100 sample liquids for random inspection and conducts tests according to the method provided by the present invention, wherein 20 samples with obvious red color are screened out and 80 samples are colorless samples; GB / T 5750.4-2006 "Standard Test Method for Drinking Water Sensory Properties and Physical Indicators" (methylene blue spectrophotometry) is then used as a reference method, and the 20 samples are tested again to confirm that they are indeed unqualified samples and 80 samples are qualified samples. This shows that the rapid detection method provided by the present invention is consistent with the results of the reference method, with a specificity of 100%.

[0041] In the present invention, 25 samples of laboratory tested liquid were taken (divided into positive samples and negative samples), and colorimetric analysis was performed according to the rapid detection method provided by the present invention. The sample results were consistent with the results of the reference method GB / T 5750.4-2006 "Standard Test Method for Drinking Water Sensory Properties and Physical Indicators" (Methylene Blue Spectrophotometry). This shows that the false negative rate of the rapid detection method provided by the present invention is 0%, and the false positive rate is 0%.

[0042] It should be noted that the conventional principle of GB 14934-2016 "National Food Safety Standard for Disinfecting Tableware (Drinking Utensils)" and similar spectrophotometric methods is: using positively charged ion complexes to react with negatively charged anionic synthetic detergents to form complexes that are insoluble in water and soluble in organic solvents, extracting with chloroform or other organic solvents, and then measuring the absorbance value of the color developing solution to quantitatively determine the content of anionic synthetic detergents in the sample. The above spectrophotometric detection steps are cumbersome and time-consuming, and require the use of a matching instrument spectrophotometer, which cannot meet the needs of rapid detection. In the present invention, after preparing the standard colorimetric card, only rhodamine B and ethyl acetate need to be added and left to stand for a while to perform rapid detection, and the results are correct, the overall operation takes a short time, and can meet the needs of rapid detection.

[0043] Example 2

[0044] The method used in this example is basically the same as that in Example 1, except that 2 mL of 60 mg / L safranin T solution and 5 mL of ethyl acetate (analytical grade) are added to 20 mL of washing solution and then the color is compared with the standard colorimetric card (the preparation method of the standard colorimetric card is the same as that in Example 1).

[0045] The detection limit in this embodiment is based on the reference in Example 1. Figure 2 As shown, the blank sample is colorless and transparent, and the samples at a concentration of 0.030 mg / L and above are obviously red. The detection limit of the method provided by the present invention is 0.0030 mg / 100 cm 2 .

[0046] The specificity test and the false negative rate and false positive rate in this example were performed with reference to Example 1. The results showed that the rapid detection method provided in this example had a specificity of 100%, a false negative rate of 0%, and a false positive rate of 0%.

[0047] Example 3

[0048] The method used in this example is basically the same as that in Example 1, except that 1 mL of 30 mg / L rhodamine 6G solution and 5 mL of ethyl acetate (analytical grade) are added to 20 mL of washing solution and then the color is compared with a standard colorimetric card (the preparation method of the standard colorimetric card is the same as that in Example 1).

[0049] The detection limit in this embodiment is based on the reference in Example 1. Figure 2 As shown, the blank sample is colorless and transparent, and the samples at a concentration of 0.030 mg / L and above have a clearly visible pink color. The detection limit of the method provided by the present invention is 0.0030 mg / 100 cm 2 .

[0050] The specificity test and the false negative rate and false positive rate in this example were performed with reference to Example 1. The results showed that the rapid detection method provided in this example had a specificity of 100%, a false negative rate of 0%, and a false positive rate of 0%.

[0051] Example 4

[0052] The method used in this example is basically the same as that in Example 1, except that 1 mL of 60 mg / L ethyl violet solution and 6 mL of ethyl acetate (analytical grade) are added to 30 mL of washing solution and then the color is compared with a standard colorimetric card (the preparation method of the standard colorimetric card is the same as that in Example 1).

[0053] The detection limit in this embodiment is carried out with reference to Example 1. Figure 2 As shown, the blank sample is colorless and transparent, and the samples at a concentration of 0.030 mg / L and above have a clearly visible purple color. The detection limit of the method provided by the present invention is 0.0030 mg / 100 cm 2 .

[0054] The specificity test and the false negative rate and false positive rate in this example were performed with reference to Example 1. The results showed that the rapid detection method provided in this example had a specificity of 100%, a false negative rate of 0%, and a false positive rate of 0%.

[0055] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A rapid detection method for anionic synthetic detergents in reusable tableware, characterized in that: include: Wash tableware with pure water and collect the washing liquid; Take the washing liquid, add the developer solution and ethyl acetate to it in sequence, shake well and let it stand for a while; Aspirate the upper clear liquid, compare the color with the standard colorimetric card, and calculate the concentration of anionic synthetic detergent in the washing liquid according to the color depth of the standard colorimetric card; Wherein, the color developing agent is rhodamine B, safranin T, rhodamine 6G, and ethyl violet.

2. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 1, characterized in that: When washing, the surface area of ​​tableware in contact with food is measured at 1 cm 2 The contact area was rinsed with 1-1.5 mL of pure water.

3. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 1, characterized in that: The volume of the washing solution is not less than 20 mL, the volume of the color developer solution is 0.5-3.0 mL, and the volume of ethyl acetate is 4-8 mL.

4. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 3, characterized in that: The concentration of the developer solution is 20-70 mg / L.

5. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 1, characterized in that: The preparation method of the standard colorimetric card is: Prepare a standard solution of sodium dodecylbenzene sulfonate with gradient concentrations; Add the color developer solution and ethyl acetate to the sodium dodecylbenzene sulfonate standard solution in sequence, shake well and let stand for a while; The upper clear liquid is aspirated to prepare standard color scale solutions, and standard color comparison cards are printed according to the color values ​​of each standard color scale solution.

6. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 5, characterized in that: The concentrations of standard sodium dodecylbenzenesulfonate solutions are 0.00mg / L, 0.010mg / L, 0.020mg / L, 0.030mg / L, 0.040mg / L, 0.050mg / L, 0.10mg / L, 0.20mg / L, 0.40mg / L, 0.50mg / L, 1.0mg / L, 2.0mg / L. 。 7. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 5, characterized in that: The volume of the sodium dodecylbenzenesulfonate standard solution is not less than 20 mL, the volume of the developer solution is 0.5-3.0 mL, and the volume of ethyl acetate is 4-8 mL.

8. The method for rapid detection of anionic synthetic detergents in recyclable tableware according to claim 5, characterized in that: The concentration of the developer solution is 20-70 mg / L.

9. A rapid detection kit for anionic synthetic detergents in tableware, characterized in that: It includes washing liquid, extracting liquid and color developing agent solution; wherein, the washing liquid is pure water, the extracting liquid is ethyl acetate, and the color developing agent is rhodamine B, safranin T, rhodamine 6G and ethyl violet.

10. The rapid detection kit for anionic synthetic detergents in tableware according to claim 9, characterized in that: The kit also includes an area measurer, which is a ruler-type tool.

Images