Method for preparing milk powder containing phthalate plasticizer and application thereof

Abstract

The invention discloses a method for preparing milk powder containing phthalate plasticizer and its application, wherein the method comprises: dissolving the phthalate plasticizer in an alcohol solution to obtain a plasticizer solution; dissolving a theoretical value of the plasticizer solution in a dairy solution, stirring it for the first time and then standing it, and stirring it for the second time to obtain a milk base liquid containing the plasticizer; and using the milk base liquid containing the plasticizer to prepare milk powder, wherein the milk powder contains the phthalate plasticizer. The method overcomes the problem that the phthalate plasticizer is difficult to dissolve in the emulsion, and the phthalate plasticizer is evenly distributed in the prepared milk powder, meeting the characteristic requirements of the standard substance.

Description

Technical Field

[0001] The present invention relates to the field of analytical chemistry, and in particular to a method for preparing milk powder containing phthalate plasticizers, and a standard milk powder containing phthalate prepared by the method. Background Art

[0002] Phthalate acid esters (PAEs) are a general term for a class of organic pollutants, which are often used in plastic products to improve product toughness. PAEs do not exist in the form of covalent bonds with the matrix, so PAEs can easily migrate into external environmental media such as air, water and soil. Studies have shown that PAEs are a class of endocrine disruptors that produce effects similar to estrogen. Some PAEs have carcinogenic properties. Among them, di(2-ethyl)hexyl phthalate (DEHP) is classified as Class 2B based on its carcinogenicity. Therefore, the U.S. Environmental Protection Agency (USEPA) lists PAEs as a priority controlled pollutant; the European Food Safety Authority (EFSA) stipulates that the maximum daily intake of dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and DEHP are 0.01 mg / kg, 0.5 mg / kg and 0.05 mg / kg respectively. Phthalate plasticizers have been detected in milk powders from Europe, the United States, Canada and Asia, with DEHP and DBP concentrations ranging from 34 to 500 μg / kg and 15 to 77 μg / kg, respectively. Plasticizers are introduced into milk powders mainly in two stages: first, they are introduced into fresh milk raw materials due to plasticizer contamination in water sources, soil and pastures; second, they migrate during the milk powder production process, such as in PVC pipes for collecting milk sources and storage tanks, due to the lipophilic properties of plasticizers.

[0003] At present, the determination of phthalates in milk powder adopts "GB 5009.271-2016 National Food Safety Standard Determination of Phthalates in Food". As an important part of analysis and detection, the role of standard substances is irreplaceable. However, standard substances for phthalates in milk powder matrix are relatively scarce, with only a few solution standard substances. For matrix detection, matrix standard substances play an indispensable role in method confirmation and evaluation, measurement quality control and other fields. The composition of milk powder matrix is ​​complex, mainly containing fat, protein and carbohydrates, and also has a small amount of vitamins, minerals and nucleotides, which increases the difficulty of plasticizer detection.

[0004] Matrix standard substances can provide a guarantee for the establishment of detection methods, accuracy and comparability of test results. Therefore, milk powder standards containing phthalate compounds that are easily soluble in water and emulsions such as cow's milk need to be studied. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a method for preparing milk powder containing phthalate plasticizer, which overcomes the problem that phthalate plasticizer is poorly soluble in emulsion, and the phthalate plasticizer is evenly distributed in the prepared milk powder.

[0006] It should be noted that the present invention is completed based on the following work of the inventors:

[0007] At present, there are difficulties in the production of plasticizer standard substances. Naturally contaminated samples are uneven, and when samples are prepared artificially, plasticizer standards are mostly soluble in organic solvents and cannot be evenly miscible with milk or reconstituted milk. The inventor creatively dissolves the plasticizer evenly into milk or reconstituted milk through a plasticizer standard solution dissolved in an alcohol solution, and adopts a wet production process to ensure that the uniformity of the plasticizer standard substance in the developed milk powder meets the requirements of ISO Guide 35 through homogenization, pasteurization, concentration, powder spraying and ingredient mixing processes. By overcoming the technical difficulties of dissolving plasticizer standards, the development and mature production process technology of milk powder matrix plasticizer standard substances have been fully mastered, filling the technical gap in my country's milk powder matrix standard substances.

[0008] Therefore, according to one aspect of the present invention, the present invention provides a method for preparing milk powder containing phthalate plasticizer. According to an embodiment of the present invention, the method comprises: dissolving the phthalate plasticizer in an alcohol solution to obtain a plasticizer solution; dissolving the theoretical value of the plasticizer solution in a dairy solution, stirring it for the first time and then standing it, and stirring it for the second time to obtain a milk base liquid containing the plasticizer; and preparing milk powder using the milk base liquid containing the plasticizer, wherein the milk powder contains the phthalate plasticizer.

[0009] According to the method for preparing milk powder containing phthalate plasticizers according to an embodiment of the present invention, the plasticizer dissolved in an alcohol solution is evenly mixed in a dairy solution, and the dairy solution is then prepared into milk powder, so that the phthalate plasticizer is evenly distributed in the milk powder, thereby solving the problem of uneven distribution of plasticizers when plasticizer standard substances are artificially prepared; and the prepared milk powder is easily soluble in water, as well as emulsions such as cow's milk and reconstituted milk, and meets the national standard requirements for milk powder matrices; and by controlling the amount of plasticizer solvent added and the total amount of milk, the expected target content of phthalate plasticizers in the milk powder can be obtained.

[0010] In addition, the method for preparing milk powder containing phthalate plasticizer according to the above embodiment of the present invention may also have the following additional technical features:

[0011] According to an embodiment of the present invention, the alcohol solution is a methanol solution.

[0012] According to an embodiment of the present invention, the theoretical value is the concentration of the methanol solution of the phthalate plasticizer multiplied by the mass of added methanol, which is added to a certain amount of milk and mixed evenly.

[0013] According to an embodiment of the present invention, the first stirring and the second stirring are both performed for 20-30 minutes, and the standing time is 30 minutes.

[0014] According to an embodiment of the present invention, the stirring and the standing are performed when the dairy solution is at 40-60°C.

[0015] According to an embodiment of the present invention, in a method for preparing milk powder by wet addition method, the milk powder containing phthalate plasticizer is prepared by using the milk base liquid containing plasticizer.

[0016] According to an embodiment of the present invention, the method for preparing milk powder using the milk base liquid containing the plasticizer includes: homogenizing the milk base liquid to obtain a homogenized liquid; sterilizing the homogenized liquid to obtain a sterilized liquid; concentrating the sterilized liquid to obtain a concentrated liquid; and powdering the concentrated liquid to obtain the milk powder containing the phthalate plasticizer.

[0017] According to an embodiment of the present invention, the phthalate plasticizer is a phthalate compound formed by phthalic acid and an alcohol having 4 to 15 carbon atoms. Specifically, according to some embodiments of the present invention, the phthalate plasticizer is selected from dimethyl phthalate / DMP, diethyl phthalate / DEP, diisobutyl phthalate / DIBP, dimethoxyethyl phthalate / DMEP, di(4-methyl-2-pentyl)phthalate / BMPP, di(2-ethoxy)ethyl phthalate / DEEP, dipentyl phthalate / DPP ...isobutyl phthalate / DIBP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DMPP, diisobutyl phthalate / DMEP, diisobutyl phthalate / DM The concentration of dihexyl phthalate / DHXP, di(2-butoxy)ethyl phthalate / DBEP, dicyclohexyl phthalate / DCHP, diphenyl phthalate / DPHP, di-n-octyl phthalate / DNOP, dinonyl phthalate / DNP is 1 mg / mL, and at least one of dibutyl phthalate / DBP, butyl benzyl phthalate / BBP and di(2-ethyl)hexyl phthalate / DEHP.

[0018] Further, according to another aspect of the present invention, the present invention provides a standard milk powder containing phthalates. According to an embodiment of the present invention, the standard milk powder is prepared by the aforementioned method for preparing milk powder containing phthalate plasticizers. As a result, the phthalate plasticizer is evenly distributed in the milk powder, solving the problem of uneven distribution of plasticizers when artificially preparing plasticizer standard substances; and the milk powder is easily soluble in water, and emulsions such as cow's milk and reconstituted milk, solving the problem that artificially prepared plasticizer standards are mostly soluble in organic solvents and cannot be miscible with cow's milk or reconstituted milk.

[0019] According to an embodiment of the present invention, the phthalate plasticizer is a phthalate compound formed by phthalic acid and an alcohol having 4 to 15 carbon atoms. Specifically, according to some embodiments of the present invention, the phthalate plasticizer is selected from dimethyl phthalate / DMP, diethyl phthalate / DEP, diisobutyl phthalate / DIBP, dimethoxyethyl phthalate / DMEP, di(4-methyl-2-pentyl)phthalate / BMPP, di(2-ethoxy)ethyl phthalate / DEEP, dipentyl phthalate / DPP, dimethoxyethyl phthalate / DMEP, di(4-methyl-2-pentyl)phthalate / BMPP, di(2-ethoxy)ethyl phthalate / DEEP, dipentyl phthalate / DPP, di(2-ethoxy)ethyl phthalate / DEEP, di(2-pentyl)phthalate / DPP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DM ...EP, di(2-pentyl)phthalate / DMPP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2-pentyl)phthalate / DMEP, di(2 The concentration of dihexyl phthalate / DHXP, di(2-butoxy)ethyl phthalate / DBEP, dicyclohexyl phthalate / DCHP, diphenyl phthalate / DPHP, di-n-octyl phthalate / DNOP, dinonyl phthalate / DNP is 1 mg / mL, and at least one of dibutyl phthalate / DBP, butyl benzyl phthalate / BBP and di(2-ethyl)hexyl phthalate / DEHP.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] Figure 1 The gas chromatography-mass spectrometry detection spectrum of phthalates in a milk powder sample according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] In the description of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0025] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0026] According to one aspect of the present invention, the present invention provides a method for preparing milk powder containing phthalate plasticizers. According to the method for preparing milk powder containing phthalate plasticizers according to an embodiment of the present invention, the phthalate plasticizers are uniformly distributed in the milk powder by uniformly mixing the plasticizer soluble in an alcohol solution in a dairy solution, and then preparing the dairy solution into milk powder, thereby solving the problem of uneven distribution of plasticizers when artificially preparing plasticizer standard substances; and the prepared milk powder is easily soluble in water, and emulsions such as cow's milk and reconstituted milk, solving the problem that artificially prepared plasticizer standards are mostly soluble in organic solvents and cannot be miscible with cow's milk or reconstituted milk. In addition, by controlling the amount of plasticizer solvent added and the total amount of milk, the phthalate plasticizer in the milk powder at the expected target content can be obtained.

[0027] In order to facilitate understanding of the method for preparing milk powder containing phthalate plasticizer, the method is explained here:

[0028] S100 Plasticizer Dissolution

[0029] According to an embodiment of the present invention, the phthalate plasticizer is dissolved in an alcohol solution to obtain a plasticizer solution. Thus, the phthalate plasticizer is easily soluble in organic solvents, and has good solubility in solvents such as methanol and n-hexane, but organic solvents such as n-hexane are immiscible with water and milk, and the addition of the organic solvents will result in uneven distribution of the plasticizer, while methanol has good solubility in water and milk, and is convenient for subsequent uniform distribution of the plasticizer.

[0030] According to an embodiment of the present invention, the alcohol solution is methanol. Phthalate has good solubility in methanol, a small amount of addition, and negligible effect on the milk matrix. Phthalate also has good solubility in water and milk, and it is easy to achieve uniform distribution of plasticizer after addition. According to an embodiment of the present invention, the methanol is pure methanol.

[0031] Preparation of S200 milk-based liquid

[0032] According to an embodiment of the present invention, a theoretical plasticizer solution is dissolved in a dairy solution, stirred for the first time and then allowed to stand, and then stirred for the second time, so as to obtain a milk base liquid containing the plasticizer. Thus, the plasticizer is evenly distributed in the dairy solution.

[0033] According to an embodiment of the present invention, the theoretical value is the theoretical concentration of the phthalate plasticizer multiplied by the total amount of the methanol solution used in the method. Specifically, the total amount of the dairy solution is the total amount of all dairy solutions used to prepare subsequent milk powder, including liquid milk and solid milk powder. The milk and milk powder are converted proportionally, that is, the ratio of milk to milk powder is 8:1. The total amount of the dairy solution includes both dairy products with plasticizer directly added and dairy products used for containers containing plasticizers again.

[0034] According to an embodiment of the present invention, the first stirring and the second stirring are both for 20-30 minutes, and the standing time is 30 minutes. This is conducive to fully mixing the plasticizer with the dairy solution, so that the plasticizer is more evenly distributed.

[0035] According to an embodiment of the present invention, the stirring and the standing are performed when the dairy solution is at 40-60° C. Specifically, the stirring temperature can be changed according to the volume and temperature of the dairy product. For example, if a new dairy solution is added during the stirring process and the temperature of the new dairy solution is low, the stirring temperature needs to be appropriately increased to keep the temperature of the dairy solution at 40-60° C. Therefore, standing under this condition is conducive to keeping the milk in a homogeneous state without causing milk stratification.

[0036] S300 milk powder preparation

[0037] According to an embodiment of the present invention, milk powder is prepared using a milk base liquid containing a plasticizer, and the milk powder contains a phthalate plasticizer. Since the plasticizer is evenly distributed in the milk base liquid, the plasticizer is evenly distributed in the milk powder prepared by the plasticizer, thereby solving the problem of uneven distribution of the plasticizer when artificially preparing a plasticizer standard substance.

[0038] According to an embodiment of the present invention, in a method for preparing milk powder by wet addition method, the milk powder containing phthalate plasticizer is prepared by using the milk base liquid containing plasticizer.

[0039] According to an embodiment of the present invention, the method for preparing milk powder using the milk base liquid containing the plasticizer includes: homogenizing the milk base liquid to obtain a homogenized liquid; sterilizing the homogenized liquid to obtain a sterilized liquid; concentrating the sterilized liquid to obtain a concentrated liquid; and powdering the concentrated liquid to obtain the milk powder containing the phthalate plasticizer.

[0040] According to an embodiment of the present invention, the pressure of the homogenization treatment is 50 / 200 bar and the time is 25 minutes.

[0041] According to an embodiment of the present invention, the sterilization treatment is a pasteurization treatment under the conditions of 90° C. for 15 seconds.

[0042] According to an embodiment of the present invention, the concentration process concentrates the sterilized liquid to 44-46%.

[0043] According to an embodiment of the present invention, in the powder spraying process, the air inlet temperature of the milk powder tower is 178-188°C, the exhaust temperature is 78-88°C, and the tower pressure is -1.0 mbar; all the milk powder after 30 minutes of feeding into the milk powder tower is collected and put into the milk powder dry mixer for mixing for 6 hours, rotating 90-100 times per hour; the dry-mixed milk powder is vacuum-packed in aluminum foil bags and stored in a freezer below -18°C.

[0044] According to an embodiment of the present invention, the phthalate plasticizer is a phthalate compound formed by phthalic acid and an alcohol having 4 to 15 carbon atoms. Specifically, according to some embodiments of the present invention, at least one of dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dimethoxyethyl phthalate (DMEP), di(4-methyl-2-pentyl) phthalate (BMPP), di(2-ethoxy)ethyl phthalate (DEEP), dipentyl phthalate (DPP), dihexyl phthalate (DHXP), di(2-butoxy)ethyl phthalate (DBEP), dicyclohexyl phthalate (DCHP), diphenyl phthalate (DPHP), di-n-octyl phthalate / DNOP, dinonyl phthalate (DNP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and di(2-ethyl)hexyl phthalate (DEHP).

[0045] Further, according to another aspect of the present invention, the present invention provides a standard milk powder containing phthalates. According to an embodiment of the present invention, the standard milk powder is prepared by the aforementioned method for preparing milk powder containing phthalate plasticizers. As a result, the phthalate plasticizer is evenly distributed in the milk powder, solving the problem of uneven distribution of plasticizers when artificially preparing plasticizer standard substances; and the milk powder is easily soluble in water, and emulsions such as cow's milk and reconstituted milk, solving the problem that artificially prepared plasticizer standards are mostly soluble in organic solvents and cannot be miscible with cow's milk or reconstituted milk.

[0046] According to an embodiment of the present invention, the phthalate plasticizer is a phthalate compound formed by phthalic acid and an alcohol having 4 to 15 carbon atoms, such as dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dimethoxyethyl phthalate (DMEP), di(4-methyl-2-pentyl) phthalate (BMPP), di(2-ethoxy)ethyl phthalate (DEEP), di(2-ethylhexyl)phthalate (DEEP), di(2-methyl-2-pentyl)phthalate (DMPP), di(2-ethylhexyl)phthalate (DEEP), di(2-ethylhexyl)phthalate (DEBP), di(2-methyl-2-pentyl)phthalate (DMPP), di(2-ethylhexyl)phthalate (DEBP), di(2-ethylhexyl)phthalate (DMEP), di(2-methyl-2-pentyl)phthalate (DMPP), di(2-ethylhexyl)phthalate (DEEP), di(2-ethylhexyl)phthalate (DEBP), di(2-methyl-2-pentyl)phthalate (DMEP), di(2-ethylhexyl)phthalate (DMEP), di(2-ethylhexyl)phthalate (DEBP), di(2-methyl-2-pentyl)phthalate (DMEP), di(2-ethylhexyl)phthalate (DEBP), di(2-ethylhexyl)phthalate (DMEP), di(2-methyl-2-pentyl)phthalate (BMPP), di(2-ethylhexyl)phthalate (DEEP), di(2-ethylhexyl)phthalate (DMEP), di(2-methyl-2-pentyl)phthalate (DMEP), di(2-ethylhex ... At least one of dibutyl phthalate (DBP), dibutyl phthalate (BBP), butyl benzyl phthalate (BBP) and di(2-ethyl)hexyl phthalate (DEHP).

[0047] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and are not to be construed as limiting the present invention.

[0048] Below in conjunction with embodiment, the scheme of the present invention will be explained.It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.Unrepresented specific techniques or conditions in the embodiment, according to the technology or conditions described in the document in this area or according to the product specification sheet.Reagents used or instruments that do not indicate manufacturers are conventional products that can be obtained commercially, for example, can be purchased from Sigma company.

[0049] Example 1

[0050] According to the method for preparing milk powder containing phthalate plasticizers according to an embodiment of the present invention, a standard milk powder containing phthalate plasticizers is prepared, and the specific steps are as follows:

[0051] Step 1: Prepare mother liquor: prepare 16 phthalate plasticizer solutions, the solvent is methanol, wherein the concentration of dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dimethoxyethyl phthalate, di(4-methyl-2-pentyl) phthalate, di(2-ethoxy)ethyl phthalate, dipentyl phthalate, dihexyl phthalate, di(2-butoxy)ethyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, di-n-octyl phthalate, and dinonyl phthalate is 1 mg / mL, and the concentration of dibutyl phthalate, butyl benzyl phthalate, and di(2-ethyl)hexyl phthalate is 12 mg / mL.

[0052] Table 1 Information on phthalate compounds

[0053]

[0054]

[0055]

[0056] Step 2 Preparation of plasticizer standard substance milk matrix intermediate liquid: Weigh 1mL of the above plasticizer solution and add it to a 500mL brown glass bottle containing 200mL of 60℃ pure water, and stir for 15min. X = theoretical addition amount per kilogram multiplied by the total amount of whole milk powder used in the batching process (the ratio of milk to milk powder is 8:1), transfer to a 5L stainless steel barrel containing 2L of 60℃ milk, add 60℃ milk to make up to 5L, stir for 30 minutes, and let stand for 30 minutes.

[0057] Step 3: Add 5L of the plasticizer standard substance milk matrix liquid prepared in step 2 into the batching tank, wash the matrix liquid container with milk three times, add all the washing milk into the batching tank, maintain the mixing temperature at 60°C, stir and mix at high shear for 20 minutes, let stand for 30 minutes for hydration, and stir and mix at high shear for 20 minutes to obtain the plasticizer standard substance milk matrix liquid.

[0058] Step 4: Homogenize: homogenize the plasticizer standard substance matrix liquid at a homogenization pressure of 50 / 200 bar for 25 minutes.

[0059] Step 5: Pasteurization: pasteurize the homogenized plasticizer standard substance matrix liquid at 90°C / 15s.

[0060] Step 6: Concentration: The pasteurized plasticizer standard substance matrix liquid is concentrated to 46%.

[0061] Step 7: Powder spraying: The uniformly concentrated plasticizer standard substance matrix liquid is powder sprayed, the milk powder tower inlet air temperature is 188°C, the exhaust air temperature is 88°C, and the tower pressure is -1.0 mbar.

[0062] Step 8 Dry Mixing: Collect all the milk powder from the milk powder tower 30 minutes after feeding, put it into the milk powder dry mixer for mixing for 6 hours, and rotate 90-100 times per hour.

[0063] Step 9: Packaging: vacuum-pack the dry-mixed milk powder in aluminum foil bags and store them in a frozen state below -18°C to obtain a standard milk powder containing phthalate plasticizers.

[0064] Example 2

[0065] Uniformity is a basic property of a standard substance, which is used to describe the spatial distribution characteristics of the properties of a standard substance. During the development (production) of a standard substance, a uniformity assessment must be performed to prove that it has good uniformity. In this example, the uniformity of the milk powder standard containing phthalate plasticizer prepared in Example 1 was tested, and the specific method is as follows:

[0066] (1) Sample pretreatment: Accurately weigh 0.5 g (accurate to 0.0001 g) of infant formula sample and add a known amount of 16 PAEs dissolved in ethanol as internal standard mixture. Vortex for 30 seconds, sonicate for 15 minutes, add 1 mL of ethanol, vortex for 1 minute, add 1 mL of n-hexane and 1 mL of acetone, and vortex for 1 minute. Centrifuge at 20°C, 1500 rpm for 1 minute, collect the upper layer of liquid into a clean 10 mL glass stoppered centrifuge tube, add 3 mL of n-hexane to the residue, vortex for 1 minute, centrifuge under the same conditions, collect the upper layer of liquid, and then use 3 mL of n-hexane to collect the upper layer of liquid under the same conditions. Liquid, the three extraction solutions were combined and slowly nitrogen-blown to 3 mL at 40 ° C to be purified. After 1.0 g of anhydrous sodium sulfate was placed on the top of the Dima glass PSA solid phase extraction column, 5 mL of acetone and 5 mL of n-hexane were used for activation, and 3 mL of the solution to be purified was added. After it was naturally drained, 5 mL of n-hexane and 5 mL of n-hexane-acetone mixed solution (V:V=60:40) were used for elution respectively. The two eluates were combined and nitrogen-blown at 40 ° C, re-dissolved in 1 mL of dichloromethane and vortexed for 30 seconds, and then divided into injection vials for GC-MS / MS detection. The parameters of GC-MS / MS detection are shown in Table 2, and the mass spectrometry parameters are shown in Table 3.

[0067] Table 2 Instrumental analysis method:

[0068]

[0069] Table 3 Mass spectrometry parameters:

[0070]

[0071]

[0072] (2) Sample testing: 11 packages were randomly selected from 200 packages of the standard substance, and 3 subsamples were taken from each package for inter-bottle and intra-bottle uniformity testing. The minimum sampling amount was 0.5 g, and the test was performed according to the gas chromatography-isotope dilution mass spectrometry method described below. The MRM test results of phthalates in milk powder samples are as follows: Figure 1 As shown. The results of variance analysis of uniformity s bb Reproducibility of the method used r Or the expected target of the uncertainty of the characteristic value. If it is not significant, the standard material is considered to be uniform. The uncertainty component u introduced by the inhomogeneity of the characteristic value to be measured should be calculated. bb , and include it in the total uncertainty of the standard material. The standard material was tested for uniformity according to the above method. The results of the uniformity test are shown in Tables 4 and 5. The results show that the uniformity of the sample is good.

[0073] Table 4 PAE uniformity data and analysis

[0074]

[0075]

[0076] Table 5 PAE uniformity data and analysis

[0077] Number of samples DHXP BBP DBEP DCHP DEHP DPHP DNOP DNP 1 0.109 1.795 0.107 0.107 3.736 0.135 0.098 0.558 2 0.108 1.797 0.106 0.106 3.72 0.125 0.105 0.555 3 0.107 1.802 0.107 0.106 3.729 0.124 0.110 0.559 4 0.109 1.813 0.106 0.107 3.746 0.125 0.095 0.557 5 0.109 1.823 0.108 0.107 3.761 0.121 0.102 0.572 6 0.106 1.801 0.105 0.107 3.719 0.123 0.106 0.571 7 0.108 1.825 0.107 0.108 3.768 0.123 0.112 0.57 8 0.107 1.797 0.105 0.108 3.697 0.129 0.104 0.567 9 0.108 1.792 0.104 0.107 3.696 0.128 0.109 0.569 10 0.105 1.802 0.108 0.106 3.734 0.127 0.100 0.567 11 0.106 1.796 0.111 0.107 3.733 0.128 0.099 0.581 12 0.106 1.795 0.111 0.107 3.748 0.134 0.110 0.567 13 0.105 1.785 0.109 0.107 3.718 0.127 0.105 0.56 14 0.106 1.81 0.108 0.106 3.716 0.128 0.102 0.571 15 0.107 1.795 0.109 0.105 3.715 0.124 0.100 0.576 average value 0.107 1.802 0.107 0.107 3.729 0.127 0.104 0.567 RSD(%) 0.01207614 0.60％ 1.90％ 0.80％ 0.60％ 3.10％ 4.80％ 1.30％ <![CDATA[Between-group variance s 1 2 > 0.0009 0.00023 0.000123 0.0017 0.0093 0.000416 0.00031 0.0019 <![CDATA[Within-group variance s 2 2 > 0.0017 1.96E-02 4.10E-03 1.60E-03 3.24E-02 8.90E-03 3.90E-03 1.80E-03 <![CDATA[s bb ]]> 0.40％ 1.70％ 0.90％ 1.60％ 2.20％ 1.80％ 1.4％ 0.30％

[0078] Comparative Example 1

[0079] Phthalate plasticizers have good solubility in n-hexane and are the preferred solvent for preparing solutions. In this comparative example, n-hexane was used to prepare 16 phthalate plasticizer solutions, including dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dimethoxyethyl phthalate, di(4-methyl-2-pentyl)phthalate, di(2-ethoxy)ethyl phthalate, dipentyl phthalate, dihexyl phthalate, di(2-butoxy)ethyl phthalate, di(2-butyl)phthalate, di(2-methoxy)ethyl phthalate, di(4-methyl-2-pentyl)phthalate, di(2-ethoxy)ethyl phthalate, di(2-butyl) ... Cyclohexyl ester, diphenyl phthalate, di-n-octyl phthalate, dinonyl phthalate concentration are all 1mg / mL, dibutyl phthalate, butyl benzyl phthalate, di(2-ethyl)hexyl phthalate are all 12mg / mL, preparation steps are the same as in Example 1, in the milk powder sample finally prepared, taking DBP as an example, the method of Example 1 is used to detect and analyze, and the sampling result is not detected, taking DEHP as an example, 3 sample results are respectively not detected, 0.5μg / g, 1.2μg / g. The result shows that phthalate plasticizer has poor uniformity, and the sample cannot meet the requirements. Therefore, n-hexane solvent can not be used to prepare phthalate plasticizer solution.

[0080] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0081] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing milk powder containing phthalate plasticizer, characterized in that: include: Step 1: Prepare stock solution dissolving a phthalate plasticizer in methanol to obtain a plasticizer solution; Step 2: Prepare the intermediate solution Add 1 mL of plasticizer solution to a 500 mL brown glass bottle containing 200 mL of 60°C pure water, stir for 15 min, then transfer to a 5 L stainless steel barrel containing 2 L of 60°C milk, add 60°C milk to make the volume 5 L, stir for 30 min, and let stand for 30 min to obtain an intermediate solution; Step 3: Preparation of standard milk-based solution containing phthalate plasticizers The intermediate liquid obtained after standing in step 2 is added to the batching tank, the stainless steel barrel is washed with milk for 3 times, and all the washing milk is added to the batching tank, the mixing temperature is maintained at 60° C., high shear stirring is performed for 20 minutes, and the mixture is allowed to stand for 30 minutes for hydration, and high shear stirring is performed for 20 minutes to obtain a standard substance milk-based liquid containing phthalate plasticizer; Step 4: Preparation of milk powder from standard milk-based liquid containing phthalate plasticizers Homogenizing a standard substance milk base liquid containing a phthalate plasticizer to obtain a homogenized liquid; Sterilize the homogenized liquid to obtain a sterilized liquid; Concentrating the sterilized liquid to obtain a concentrated liquid; and The concentrated liquid material is subjected to powder spraying treatment to obtain milk powder containing phthalate plasticizer.

2. The method according to claim 1, characterized in that Phthalate plasticizers are phthalate compounds formed by phthalic acid and alcohols with 4 to 15 carbon atoms.

3. The method according to claim 2, characterized in that The phthalate plasticizer is at least one of dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dimethoxyethyl phthalate, di(4-methyl-2-pentyl)phthalate, di(2-ethoxy)ethyl phthalate, dipentyl phthalate, dihexyl phthalate, di(2-butoxy)ethyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, di-n-octyl phthalate, dinonyl phthalate, dibutyl phthalate, butyl benzyl phthalate and di(2-ethyl)hexyl phthalate.

4. A standard milk powder containing phthalates, characterized in that: The milk powder standard is prepared by the method for preparing milk powder containing phthalate plasticizer according to any one of claims 1 to 3.

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