Method for analyzing content of chloropropanol in hydroxypropyl modified starch

Abstract

The invention belongs to the field of food detection, and particularly relates to a method for analyzing the content of chloropropanol in hydroxypropyl modified starch, which comprises the following steps: mixing a to-be-detected sample, amylase and water, and heating to hydrolyze the to-be-detected sample to obtain a hydrolysate; cooling the hydrolysate, mixing the cooled hydrolysate with a salting-out agent, adding an extracting agent, oscillating, centrifuging, and collecting an upper solution; mixing the upper-layer solution with an extracting agent, repeating the process of oscillating, centrifuging and collecting the upper-layer solution twice, combining the upper-layer solutions collected three times to obtain an extracting solution, and concentrating the extracting solution to obtain a solution to be detected; preparing gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol, carrying out GC-MS / MS (Gas Chromatography-Mass Spectrometry / Mass Spectrometry) analysis, and drawing a working curve; and analyzing the to-be-detected solution by using the same parameters, and calculating the actual content of chloropropanol in the to-be-detected sample. According to the method provided by the invention, the limit of quantitation can reach 0.01 mg / kg, the accuracy is high, and the chloropropanol in the modified starch can be accurately analyzed.

Description

Technical Field

[0001] The invention belongs to the field of food detection, and in particular relates to a method for analyzing the content of chloropropanol in hydroxypropyl modified starch. Background Art

[0002] Chloropropanol is an organic substance with the chemical formula C3H7ClO. It is a class of compounds produced by the replacement of the hydroxyl group on glycerol with chlorine. There are three isomers, namely 2-chloro-1-propanol, 3-chloro-1-propanol, and 1-chloro-2-propanol. All three isomers are colorless liquids. In the production process of hydroxypropyl modified starch, the main chloropropanols produced are 2-chloro-1-propanol and 1-chloro-2-propanol. Accordingly, the Joint Expert Committee on Food Additives (JECFA) and the United States Food Chemicals Pharmacopoeia (FCC 11) and the national standard GB29931-2013 "Food Additive Hydroxypropyl Distarch Phosphate" all clearly stipulate that the content of chloropropanol in hydroxypropyl modified starch shall not exceed 1 mg / kg, and its main concern is the total amount of 1-chloro-2-propanol and 2-chloro-1-propanol. Therefore, how to accurately analyze the content of 1-chloro-2-propanol and 2-chloro-1-propanol in hydroxypropyl modified starch and its products is very important for ensuring food safety and human health.

[0003] The existing standard pre-treatment steps for the analysis of chloropropanol in modified starch are cumbersome, using sulfuric acid for hydrolysis, which is dangerous and easy to cause loss of the target object. In addition, the hydrogen flame detector is used for testing, which has low sensitivity.

[0004] In addition, the related methods for detecting chloropropanol in hydroxypropyl modified starch disclosed in the prior art can only propose free 1-chloro-2-propanol and 2-chloro-1-propanol. Since no hydrolysis is performed, the 1-chloro-2-propanol and 2-chloro-1-propanol contained in the sample matrix cannot be completely extracted, resulting in the analysis result being lower than the actual value. Secondly, the chloropropanol mixed solution (including 1-chloro-2-propanol with a mass fraction of 75% and 2-chloro-1-propanol with a mass fraction of 25%) used in the method of the prior art only considers 1-chloro-2-propanol when calculating the quantitative limit, and does not simultaneously test the quantitative limit of 2-chloro-1-propanol. The final result obtained is actually different from the content of 1-chloro-2-propanol, 2-chloro-1-propanol and 2-chloro-1-propanol in the sample, and accurate analysis cannot be achieved.

[0005] Therefore, there is an urgent need in the art for a method for detecting the content of chloropropanol in hydroxypropyl-modified starch with high measurement accuracy. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for analyzing the content of chloropropanol in hydroxypropyl modified starch, aiming to solve the problem that the prior art cannot accurately analyze the content of chloropropanol in modified starch.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for analyzing the content of chloropropanol in hydroxypropyl modified starch, comprising the following steps:

[0009] S1. The sample to be tested, amylase, and water are mixed and heated to hydrolyze the sample to be tested to obtain a hydrolyzate;

[0010] S2. Cool the hydrolyzate, mix the cooled hydrolyzate with the salting-out agent, add the extractant, oscillate, centrifuge, and collect the upper solution;

[0011] S3. The upper solution was mixed with the extractant, and the process of oscillation, centrifugation, and collection of the upper solution was repeated twice, and the upper solution collected three times was combined to obtain an extract, and the extract was concentrated to obtain a test solution;

[0012] S4. Prepare gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol and perform GC-MS / MS analysis, and draw a working curve based on the analysis results;

[0013] S5. Analyze the test solution according to the GC-MS / MS analysis parameters of S4 and calculate the actual content of chloropropanol in the test sample. The result formula is as follows:

[0014]

[0015] Where:

[0016] X 氯丙醇 ——Total content of 1-chloro-2-propanol and 2-chloro-1-propanol in the sample, in milligrams per kilogram (mg / kg);

[0017] c1——the concentration of 1-chloro-2-propanol obtained from the working curve, in milligrams per liter (mg / L);

[0018] c2——the concentration of 2-chloro-1-propanol obtained from the working curve, in milligrams per liter (mg / L);

[0019] V——The volume of the test solution after concentration, in liters (L);

[0020] m——sample mass, in grams (g).

[0021] Optionally, in step S1, the mass volume ratio of the sample to be tested, amylase and water is (3.0-8.0) g: (0.8-1.2) g: (8-12) mL.

[0022] Optionally, the heating temperature in step S1 is 80-100° C., and the heating time is 40-80 min.

[0023] Optionally, the amylase is any one of α-amylase, β-amylase, glucoamylase and isoamylase.

[0024] Optionally, in step S2, the mass volume ratio of the salting-out agent to the extractant is (3-8) g: (10-20) mL.

[0025] Optionally, the salting-out agent in step S2 is one or more of sodium chloride, sodium sulfate, magnesium sulfate, and magnesium chloride, and the extracting agent is a mixed solution of ether and ethyl acetate.

[0026] Furthermore, the volume ratio of ether to ethyl acetate in the extractant is (3:7) to (7:3).

[0027] Optionally, the oscillation time in step S2 and step S3 is 3 to 8 minutes.

[0028] Optionally, the centrifugation time in step S2 and step S3 is 2 to 8 minutes, and the centrifugation speed is 3000 to 5000 rpm.

[0029] Optionally, in step S4, the concentrations of the gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol are 0.02 mg / L, 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, and 0.5 mg / L, respectively.

[0030] Optionally, the GC-MS / MS analysis in step S4 includes the following parameters:

[0031] Chromatographic temperature program: maintain at 50-70°C for 1-3 min, then increase to 210-230°C at a heating rate of 15-25°C / min and maintain for 1-3 min;

[0032] Carrier gas: helium, purity ≥ 99.999%;

[0033] Carrier gas flow rate: 0.5~1.5mL / min;

[0034] Inlet temperature: 220~240℃;

[0035] Injection volume: 1.0 μL;

[0036] Injection mode: split injection, split ratio 4:1;

[0037] Electron bombardment source: 70eV;

[0038] Ion source temperature: 220~240℃;

[0039] Mass spectrometer transmission interface temperature: 250~270℃;

[0040] Mass spectrometry monitoring mode: multiple reaction monitoring.

[0041] Beneficial effects of the present invention:

[0042] (1) Compared with the existing standards, the invention adopts the method of amylase hydrolysis, which can completely hydrolyze at 80-100°C without any excess sample residue, which is safe and efficient.

[0043] (2) Compared with the prior art, the present invention uses a mixed solution of ether and ethyl acetate as an extractant, which can fully extract the target substance from the sample to be tested under the action of a salting-out agent.

[0044] (3) The quantitative limit of the present invention can reach 0.01 mg / kg, with high precision, and can accurately analyze the content of chloropropanol in modified starch. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is the working curve diagram of 1-chloro-2-propanol in Example 1.

[0046] Figure 2 It is the working curve diagram of 2-chloro-1-propanol in Example 1.

[0047] Figure 3 The figure is a graph showing the recovery rate and hydrolysis temperature of 1-chloro-2-propanol in Verification Example 1.

[0048] Figure 4 The figure is a graph showing the recovery rate and hydrolysis temperature of 2-chloro-1-propanol in Verification Example 1.

[0049] Figure 5 Spectra of 0.5 mg / L of existing standard analysis and 0.5 mg / L of 1-chloro-2-propanol and 2-chloro-1-propanol samples.

[0050] Figure 6 The spectra of 0.05 mg / L and 0.05 mg / L 1-chloro-2-propanol and 2-chloro-1-propanol samples analyzed by the method of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0052] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0053] "Optional" or "any one" means that the subsequently described matter or event can or cannot occur, and that the description includes instances where the event occurs and instances where it does not.

[0054] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0055] The terms "one embodiment", "some embodiments", "exemplarily", "specific examples" or "some examples" described in the present invention mean 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 document, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0056] The numerical range described in the present invention not only includes the point values ​​listed in the embodiments, but also includes any point values ​​not listed between the numerical ranges described in the present invention. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0057] In the following examples, unless otherwise specified, all reagents and consumables were purchased from conventional reagent manufacturers in the field.

[0058] Modified starch is an indispensable food additive in our daily diet. It can be used as a thickener and stabilizer to improve the texture, taste and stability of food. Many scientists have developed a variety of functional modified starches to improve the quality of traditional foods such as vermicelli and noodles, such as hydroxypropyl modified starch, pregelatinized modified starch, acid-hydrolyzed modified starch, oxidized modified starch, esterified modified starch, etherified modified starch, cross-linked modified starch, etc. However, in the production process of modified starch, especially in the production of hydroxypropyl modified starch, propylene oxide, hydrogen chloride and other chemicals are used. If the reaction conditions are not properly controlled or the raw materials contain impurities, it may cause incomplete reaction or degradation of propylene oxide, thereby generating chloropropanol. Chloropropanol is genotoxic and long-term intake may be harmful to human health. Studies have shown that chloropropanol can bind to DNA, causing gene mutations and cell damage. In addition to genotoxicity, chloropropanol can also affect the nervous system, causing damage to the nervous system, which may lead to memory loss and abnormal behavior. At the same time, chloropropanol can also cause liver and kidney damage, increasing the risk of cancer. Due to the possible harm of chloropropanol to human body, it is very important to strictly control the content of chloropropanol in hydroxypropyl modified starch.

[0059] However, both the existing relevant standards and the existing methods have the problems of low precision and high quantitative limit when analyzing the content of chloropropanol in hydroxypropyl modified starch.

[0060] Based on this, in order to solve the above problems existing in the art, the present application provides a method for analyzing the content of chloropropanol in hydroxypropyl modified starch, comprising the following steps:

[0061] S1. The sample to be tested, amylase, and water are mixed and heated to hydrolyze the sample to be tested to obtain a hydrolyzate;

[0062] S2. Cool the hydrolyzate, mix the cooled hydrolyzate with the salting-out agent, add the extractant, oscillate, centrifuge, and collect the upper solution;

[0063] S3. The upper solution was mixed with the extractant, and the process of oscillation, centrifugation, and collection of the upper solution was repeated twice, and the upper solution collected three times was combined to obtain an extract, and the extract was concentrated to obtain a test solution;

[0064] S4. Prepare gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol and perform GC-MS / MS analysis, and draw a working curve based on the analysis results;

[0065] S5. Analyze the test solution according to the GC-MS / MS analysis parameters of S4 and calculate the actual content of chloropropanol in the test sample. The result formula is as follows:

[0066]

[0067] Where:

[0068] X 氯丙醇 ——Total content of 1-chloro-2-propanol and 2-chloro-1-propanol in the sample, in milligrams per kilogram (mg / kg);

[0069] c1——the concentration of 1-chloro-2-propanol obtained from the working curve, in milligrams per liter (mg / L);

[0070] c2——the concentration of 2-chloro-1-propanol obtained from the working curve, in milligrams per liter (mg / L);

[0071] V——The volume of the test solution after concentration, in liters (L);

[0072] m——sample mass, in grams (g).

[0073] In the scheme of the present application, the pre-treatment process of the sample to be tested is simple, which shortens the test time.

[0074] In some specific embodiments, the mass volume ratio of the sample to be tested, amylase, and water in step S1 is (3.0-8.0) g: (0.8-1.2) g: (8-12) mL. As an example, the mass volume ratio of the sample to be tested, amylase, and water in step S1 can be 3.0 g: 0.8 g: 8 mL, 3.5 g: 0.9 g: 9 mL, 4.0 g: 1.0 g: 10 mL, 4.5 g: 1.1 g: 11 mL, 5.5 g: 1.0 g: 10 mL, 6.0 g: 1.0 g: 10 mL, 7.0 g: 1.0 g: 10 mL, 8.0 g: 1.2 g: 12 mL, as long as the mass volume ratio of the sample to be tested, amylase, and water is within this range.

[0075] In some specific embodiments, the heating temperature in step S1 is 80-100°C. As an example, the heating temperature in step S1 can be 80°C, 85°C, 90°C, 95°C, or 100°C. As long as the heating temperature is within the range, the modified starch is hydrolyzed into a transparent state within the hydrolysis temperature range, which is conducive to the next step of extraction.

[0076] In some specific embodiments, the heating time in step S1 is 40 to 80 min. As an example, the heating time can be 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, or 80 min, as long as the heating time is within the range.

[0077] In some specific embodiments, the amylase is any one of α-amylase, β-amylase, glucoamylase and isoamylase, and the above amylases can hydrolyze the macromolecular modified starch in the test sample into small molecular substances under heating conditions, making the test sample clearer.

[0078] In particular, the amylase used is α-amylase, which randomly cuts α-1,4-glycosidic bonds inside the modified starch molecules to quickly liquefy the starch. When β-amylase acts on modified starch, the hydrolysis products are mainly maltose and limit dextrin. During the hydrolysis process, it cannot randomly cut α-1,4-glycosidic bonds inside the starch molecules like α-amylase to quickly liquefy the starch. Therefore, using α-amylase for hydrolysis can achieve a better hydrolysis effect.

[0079] In some specific embodiments, the mass volume ratio of the salting-out agent to the extractant in step S2 is (3-8) g: (10-20) mL. As an example, the mass volume ratio of the salting-out agent to the extractant in step S2 can be 3 g: 10 mL, 4 g: 10 mL, 4 g: 11 mL, 5 g: 12 mL, 5 g: 13 mL, 5 g: 14 mL, 5 g: 15 mL, 6 g: 15 mL, 7 g: 16 mL, 7 g: 17 mL, 7 g: 18 mL, 7 g: 19 mL, 8 g: 19 mL, 8 g: 20 mL, as long as the mass volume ratio is within the range.

[0080] In some specific embodiments, the salting-out agent in step S2 is sodium chloride, and the extracting agent is a mixed solution of ether and ethyl acetate. Sodium chloride is added to the hydrolyzate as a salting-out agent to form a saturated sodium chloride solution, which not only has a good extraction effect on the target in the hydrolyzate, but also can precipitate other components outside the target that interfere with the test.

[0081] In some specific embodiments, the salting-out agent may be sodium sulfate, magnesium sulfate, or magnesium chloride in addition to sodium chloride. The amount used may be determined based on actual conditions, and this embodiment does not impose any additional limitations.

[0082] In a specific embodiment, the volume ratio of diethyl ether to ethyl acetate in the extractant is (3:7) to (7:3). As an example, the volume ratio can be 3:7, 4:6, 5:5, 6:4, or 7:3, as long as the volume ratio of diethyl ether to ethyl acetate is within the range.

[0083] In a specific embodiment, the volume ratio of ether to ethyl acetate in the extractant is 6: 4. The extractant at this volume ratio has high extraction efficiency and is not prone to loss of the target when switching solvents.

[0084] In some specific embodiments, the oscillation time in step S2 and step S3 is 3 to 8 minutes. As an example, the oscillation time in step S2 and step S3 can be 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, as long as the oscillation time is within the range.

[0085] In some specific embodiments, the centrifugation time in step S2 and step S3 is 2 to 8 minutes. As an example, the centrifugation time can be 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, or 8 minutes, as long as the centrifugation time is within the range.

[0086] In some specific embodiments, the centrifugal speed in steps S2 and S3 is 3000-5000 rpm. As an example, the centrifugal speed can be 3000 rpm, 3250 rpm, 3500 rpm, 3750 rpm, 4000 rpm, 4250 rpm, 4500 rpm, 4750 rpm, or 5000 rpm, as long as the centrifugal speed is within the range.

[0087] In some specific embodiments, the volume of the extractant added in steps S2 and S3 is 10-20 mL. As an example, the volume of the extractant can be 10 mL, 11 mL, 12 mL, 13 mL, 14 mL, 15 mL, 16 mL, 17 mL, 18 mL, 19 mL, 20 mL, as long as the volume of the extractant is within the range.

[0088] In some specific embodiments, the concentrations of the gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol in step S4 are 0.02 mg / L, 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, and 0.5 mg / L, respectively.

[0089] In some specific embodiments, the analysis parameters of GC-MS / MS can be:

[0090] Chromatographic temperature program: maintain at 50-70°C for 1-3 min, then increase to 210-230°C at a heating rate of 15-25°C / min and maintain for 1-3 min;

[0091] Carrier gas: helium, purity ≥ 99.999%;

[0092] Carrier gas flow rate: 0.5~1.5mL / min;

[0093] Inlet temperature: 220-240°C; S4. Prepare gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol and perform GC-MS / MS analysis to draw a working curve. The specific parameters are as follows:

[0094] Chromatographic column: HP-INNOWAX, 30m×0.250mm×0.25μm, capillary column or equivalent;

[0095] Chromatographic temperature program: maintain at 50-70°C for 1-3 min, then increase to 210-230°C at a heating rate of 15-25°C / min and maintain for 1-3 min;

[0096] Carrier gas: Helium, purity ≥ 99.999%,

[0097] Carrier gas flow rate: 0.5~1.5mL / min;

[0098] Inlet temperature: 220~240℃;

[0099] Injection volume: 1.0 μL;

[0100] Injection mode: split injection, split ratio 4:1;

[0101] Electron bombardment source: 70eV;

[0102] Ion source temperature: 220~240℃;

[0103] Mass spectrometer transmission interface temperature: 250~270℃;

[0104] Mass spectrometry monitoring mode: multiple reaction monitoring;

[0105] Mass spectrometry quantitative ion pair and qualitative ion pair collision voltage:

[0106]

[0107] In some specific embodiments, the endpoint temperature of the first heating stage of the chromatography is 50-70°C. As an example, the endpoint temperature of the first heating stage can be 50°C, 55°C, 60°C, 65°C, or 70°C, as long as the endpoint temperature of the first heating stage is within the range.

[0108] In some specific embodiments, the holding time of the end point of the first heating stage of the chromatography is 1 to 3 minutes. As an example, the holding time can be 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, or 3 minutes, as long as the holding time of the first heating stage of the chromatography is within the range.

[0109] In some specific embodiments, the heating rate of the second heating stage of the chromatography is 15-25°C / min. As an example, the heating rate of the second heating stage of the chromatography can be 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, 20°C / min, 21°C / min, 22°C / min, 23°C / min, 24°C / min, or 25°C / min, as long as the heating rate of the second heating stage is within this range.

[0110] In some specific embodiments, the end point of the second heating stage of the chromatography is 210-230°C. As an example, the end point of the second heating stage can be 210°C, 215°C, 220°C, 225°C, or 230°C, as long as the end point of the second heating stage is within the range.

[0111] In some specific embodiments, the endpoint holding time of the second heating stage of the chromatography is 1 to 3 minutes. As an example, the endpoint holding time of the second heating stage can be 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, or 3 minutes, as long as the endpoint holding time of the second heating stage of the chromatography is within the range.

[0112] In some specific embodiments, the flow rate of the carrier gas is 0.5-1.5 mL / min. As an example, the flow rate of the carrier gas can be 0.5 mL / min, 0.6 mL / min, 0.7 mL / min, 0.8 mL / min, 0.9 mL / min, 1.0 mL / min, 1.1 mL / min, 1.2 mL / min, 1.3 mL / min, 1.4 mL / min, 1.5 mL / min, as long as the flow rate of the carrier gas is within the range.

[0113] In some specific embodiments, the temperature of the injection port is 220-240°C. As an example, the temperature of the injection port can be 220°C, 225°C, 230°C, 235°C, or 240°C, as long as the injection port temperature is within the range.

[0114] In some specific embodiments, the temperature of the ion source is 220-240°C. As an example, the temperature of the ion source can be 220°C, 225°C, 230°C, 235°C, or 240°C, as long as the temperature of the ion source is within the range.

[0115] In some specific embodiments, the temperature of the mass spectrometry transmission interface is 250-270°C. As an example, the temperature of the mass spectrometry transmission interface can be 250°C, 255°C, 260°C, 265°C, or 270°C, as long as the temperature of the mass spectrometry transmission interface is within the range.

[0116] Reagent preparation

[0117] The information of chloropropanol standard is shown in Table 1.

[0118] Table-1 Chloropropanol Product Information Table

[0119] Chinese name English name CAS Number purity 1-Chloro-2-propanol 1-Chloro-2-propanol 127-00-4 98.9％ 2-Chloro-1-propanol 2-Chloro-1-proranol 78-89-7 95.2％

[0120] Standard stock solution: Accurately weigh appropriate amounts of 1-chloro-2-propanol and 2-chloro-1-propanol standard substances, dissolve them in ethyl acetate to prepare a standard stock solution with a concentration of 1000 mg / L, and store the solution in a refrigerator at 0-4°C.

[0121] Standard intermediate solution (10 mg / L): Accurately pipette 1 mL of 1-chloro-2-propanol and 2-chloro-1-propanol standard stock solutions into a 100 mL volumetric flask, dilute to the mark with ethyl acetate, mix well, and set aside.

[0122] The following is a brief introduction to the principle of qualitative and quantitative analysis of chloropropanol in modified starch by this application:

[0123] qualitative principle

[0124] According to the conditions of step S4, a working curve is drawn. The retention time of the mass chromatographic peak of the sample to be tested should be consistent with that of the standard substance, with an allowable deviation of less than ±0.5%. In addition, in the mass spectrum of the sample after background subtraction, the selected ions all appear and the signal-to-noise ratio is ≥3. Moreover, the relative abundance of the qualitative ion pair and the relative abundance of the standard solution with equivalent concentration have an allowable deviation that does not exceed the range specified in Table 2. It can be determined that the corresponding analyte exists in the sample.

[0125] Table-2 Maximum allowable deviation of relative ion abundance in qualitative analysis

[0126] Relative ion abundance ＞50％ 20%~50%(inclusive) 10%~20%(inclusive) ≤10％ Maximum allowed deviation ±20％ ±25％ ±30％ ±50％

[0127] Quantitative principle

[0128] Inject the test solution into the gas chromatography-mass spectrometer / mass spectrometer to obtain the peak areas of 1-chloro-2-propanol and 2-chloro-1-propanol, and obtain the concentration of the test compound in the sample solution according to the working curve. The peak area of ​​chloropropanol in the sample solution should be within the linear range of the working curve; if the content exceeds the range of the working curve, adjust the sample weight or constant volume and retest to obtain the quantitative result.

[0129] The present invention will be further described below by means of specific embodiments:

[0130] Example 1

[0131] Weigh 5.0 g of cassava hydroxypropyl modified starch, put it in a 50 mL centrifuge tube, add 1 g of α-amylase, add 10 mL of pure water, mix and shake to dissolve the sample, make the sample into a paste, put it in an 80 ° C water bath and heat for 60 min, take it out and mix it evenly every 10 min, return to room temperature after hydrolysis is completed, add 5 g of sodium chloride and shake it, add 15 mL of ether: ethyl acetate (6:4) and shake it for 5 min, and then centrifuge it at 4000 rpm for 3 min after the shaking ends. The supernatant after centrifugation is further mixed with 10 mL of ether and ethyl acetate with a volume ratio of 6:4, and then centrifuged twice, using 10 mL of extractant for each extraction, and the supernatant is combined for 3 times and hydraulically concentrated to less than 1 mL, and the volume is fixed to 1 mL with ethyl acetate to obtain the test solution.

[0132] The standard intermediate solutions of 1-chloro-2-propanol and 2-chloro-1-propanol were used to prepare gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol, with concentrations of 0.02 mg / L, 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, and 0.5 mg / L, respectively. The gradient concentration standard solutions were analyzed by GC-MS / MS, and the working curve was drawn. The specific parameters are as follows:

[0133] Chromatographic column: HP-INNOWAX, 30m×0.250mm×0.25μm, capillary column;

[0134] Chromatographic temperature program: maintain at 60 °C for 2 min, then increase to 220 °C at a rate of 20 °C / min and maintain for 2 min;

[0135] Carrier gas: Helium, purity ≥ 99.999%,

[0136] Carrier gas flow rate: 1.0 mL / min;

[0137] Inlet temperature: 230°C;

[0138] Injection volume: 1.0 μL;

[0139] Injection mode: split injection, split ratio 4:1;

[0140] Electron bombardment source: 70eV;

[0141] Ion source temperature: 230°C;

[0142] Mass spectrometer transmission interface temperature: 260°C;

[0143] Mass spectrometry monitoring mode: multiple reaction monitoring;

[0144] Mass spectrometry quantitative ion pair and qualitative ion pair collision voltage:

[0145]

[0146] The working curve of 1-chloro-2-propanol is as follows Figure 1 As shown, the working curve of 2-chloro-1-propanol is as follows Figure 2 The same analytical parameters as those used to draw the working curve were used to perform GC-MS / MS analysis on the test solution, and the calculation was performed according to the formula, which is as follows:

[0147]

[0148] Where:

[0149] X 氯丙醇 ——Total content of 1-chloro-2-propanol and 2-chloro-1-propanol in the sample, in milligrams per kilogram (mg / kg);

[0150] c1——the concentration of 1-chloro-2-propanol obtained from the working curve, in milligrams per liter (mg / L);

[0151] c2——the concentration of 2-chloro-1-propanol obtained from the working curve, in milligrams per liter (mg / L);

[0152] V——The volume of the test solution after concentration, in liters (L);

[0153] m——sample mass, in grams (g).

[0154] The sample was analyzed to be a negative sample and did not contain 1-chloro-2-propanol or 2-chloro-1-propanol.

[0155] Example 2

[0156] Weigh 3.0 g of corn hydroxypropyl modified starch, put it in a 50 mL centrifuge tube, add 0.8 g of α-amylase, add 8 mL of pure water, mix and shake to dissolve the sample, make the sample into a paste, put it in a 90 ° C water bath and heat for 80 minutes, take it out and mix it evenly every 10 minutes, return to room temperature after hydrolysis is completed, add 3 g of sodium sulfate decahydrate and shake, add 15 mL of ether: ethyl acetate (6:4) and shake for 5 minutes, and then centrifuge at 3000 rpm for 8 minutes after the shaking ends. The supernatant after centrifugation is further mixed with 15 mL of ether and ethyl acetate with a volume ratio of 6:4. Centrifuge twice, use 15 mL of extractant for each extraction, and combine the supernatants of 3 times to obtain the test solution.

[0157] The working curve drawn in Example 1 was used to perform qualitative and quantitative analysis on the test liquid according to the GC-MS / MS parameters of Example 1. The analysis revealed that the sample contained 1-chloro-2-propanol at a content of 0.086 mg / kg.

[0158] Example 3

[0159] Weigh 8.0 g of potato hydroxypropyl modified starch, place it in a 50 mL centrifuge tube, add 1.2 g of α-amylase, add 12 mL of pure water, mix and shake to dissolve the sample, make the sample into a paste, put it in a 100 ° C water bath and heat for 40 minutes, take it out every 5 minutes and mix it evenly, return to room temperature after hydrolysis is completed, add 8 g of magnesium chloride and shake it, add 20 mL of ether: ethyl acetate (6:4) and shake it for 5 minutes, and then centrifuge it at 5000 rpm for 2 minutes after the shaking ends. The supernatant after centrifugation is continued to be mixed with 20 mL of ether and ethyl acetate with a volume ratio of 6:4. Centrifuge twice, use 20 mL of extractant for each extraction, and combine the supernatants of 3 times to obtain the test solution.

[0160] The working curve drawn in Example 1 was used to perform qualitative and quantitative analysis on the test liquid according to the GC-MS / MS parameters of Example 1. The analysis showed that the sample contained both 1-chloro-2-propanol and 2-chloro-1-propanol, wherein the content of 1-chloro-2-propanol was 0.208 mg / kg, and the content of 2-chloro-1-propanol was 0.0015 mg / kg.

[0161] In order to further prove the accuracy and reliability of the method provided by the present invention, verification tests and comparative tests are now carried out.

[0162] Verification Example 1

[0163] This verification example is to examine the effect of different hydrolysis temperatures on the recovery rate of chloropropanols, as follows:

[0164] Take a negative hydroxypropyl modified starch sample, add the same concentration (0.1 mg / kg) of 1-chloro-2-propanol and 2-chloro-1-propanol, hydrolyze under water bath conditions with different hydrolysis temperatures (65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 100°C), extract and concentrate according to the steps of Example 1, and finally measure 1-chloro-2-propanol and 2-chloro-1-propanol on the GC-MS / MS parameters of Example 1, and calculate the results with the response value of the standard substance of 0.5 mg / L, and the recovery results of 1-chloro-2-propanol and 2-chloro-1-propanol are shown in Table 3, and the curve diagram of the recovery rate of 1-chloro-2-propanol and the hydrolysis temperature is shown in Table 3. Figure 3 As shown, the curve of the recovery rate of 2-chloro-1-propanol and the hydrolysis temperature is as follows Figure 4 shown.

[0165] Table-3 Relationship between hydrolysis temperature and recovery rate

[0166]

[0167] Through Table 3, Figure 3 and Figure 4It can be seen that the recovery rate of the hydroxypropyl starch sample basically reaches the highest value under the water bath condition of 80°C, and the hydrolysis is completely completed. However, as the hydrolysis temperature gradually increases, when the temperature is higher than 85°C, the recovery rates of the two chloropropanols decrease slightly. The inventors speculate that this is because the excessively high hydrolysis temperature causes the two chloropropanols to volatilize and lose, but it still does not affect the analysis of the sample.

[0168] Verification Example 2

[0169] Six negative hydroxypropyl modified starch samples were weighed, 1-chloro-2-propanol and 2-chloro-1-propanol were added at a sample concentration of 0.05 mg / kg, and hydrolyzed in a water bath at 80°C. The samples were extracted and concentrated according to the steps of Example 1. Finally, 1-chloro-2-propanol and 2-chloro-1-propanol were determined on the GC-MS / MS machine according to the GC-MS / MS parameters of Example 1, and the precision was calculated as shown in Table 4.

[0170] Table-4 Precision verification of spike recovery test

[0171]

[0172]

[0173] As can be seen from Table 4, the method provided by the present invention has a small deviation from the standard result when analyzing two chloropropanols, which shows that the method provided by the present invention has good repeatability and precision.

[0174] Verification Example 3

[0175] Ten hydroxypropyl modified starches from different manufacturers were selected and subcontracted to a laboratory capable of testing this project for method comparison. The comparison was conducted using different methods, and the results are shown in Table 5.

[0176] Table 5 Analysis results of three modified starches by standard GB 29930-2013 and the method of Example 1

[0177]

[0178] It can be seen from Table 5 that the quantitative limit of the existing standard test is 0.1 mg / kg, while the quantitative limit of the test method of Example 1 can reach 0.01 mg / kg, which can accurately quantify the value below the quantitative limit of the national standard method.

[0179] Comparative Example 1

[0180] This comparative example compares the differences, advantages and disadvantages between the existing standards and the method provided by the present invention, as shown in Table 6.

[0181] Table-6 Comparison details between the present invention and existing standards

[0182]

[0183]

[0184] Comparative Example 2

[0185] This comparative example compares the differences, advantages and disadvantages between the prior art and the method provided by the present invention, as shown in Table 7.

[0186] Table-7 Comparison details between the present invention and the prior art

[0187]

[0188]

[0189] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for analyzing the content of chloropropanol in hydroxypropyl modified starch, characterized in that: The following steps are involved: S1. The sample to be tested, amylase, and water are mixed and heated to hydrolyze the sample to be tested to obtain a hydrolyzate; S2. Cool the hydrolyzate, mix the cooled hydrolyzate with the salting-out agent, add the extractant, oscillate, centrifuge, and collect the upper solution; S3. The upper solution was mixed with the extractant, and the process of oscillation, centrifugation, and collection of the upper solution was repeated twice, and the upper solution collected three times was combined to obtain an extract, and the extract was concentrated to obtain a test solution; S4. Prepare gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol and perform GC-MS / MS analysis, and draw a working curve based on the analysis results; S5. Analyze the test solution according to the GC-MS / MS analysis parameters of S4 and calculate the actual content of chloropropanol in the test sample. The result formula is as follows: Where: X 氯丙醇 ——Total content of 1-chloro-2-propanol and 2-chloro-1-propanol in the sample, in milligrams per kilogram (mg / kg); c1——the concentration of 1-chloro-2-propanol obtained from the working curve, in milligrams per liter (mg / L); c2——the concentration of 2-chloro-1-propanol obtained from the working curve, in milligrams per liter (mg / L); V——The volume of the test solution after concentration, in liters (L); m——sample mass, in grams (g).

2. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: In step S1, the mass volume ratio of the sample to be tested, amylase, and water is (3.0-8.0) g: (0.8-1.2) g: (8-12) mL.

3. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: The heating temperature in step S1 is 80-100° C., and the heating time is 40-80 min.

4. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: The amylase is any one of α-amylase, β-amylase, glucoamylase and isoamylase.

5. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: The mass volume ratio of the salting-out agent to the extractant in step S2 is (3-8) g: (10-20) mL.

6. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 5, characterized in that: The salting-out agent in step S2 is one or more of sodium chloride, sodium sulfate, magnesium sulfate, and magnesium chloride, and the extracting agent is a mixed solution of ether and ethyl acetate.

7. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 6, characterized in that: The volume ratio of ether to ethyl acetate in the extractant is (3:7) to (7:3).

8. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: The oscillation time in step S2 and step S3 is 3 to 8 minutes; The centrifugal time in step S2 and step S3 is 2 to 8 minutes, and the centrifugal speed is 3000 to 5000 rpm.

9. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: In step S4, the concentrations of the gradient concentration standard solutions of 1-chloro-2-propanol and 2-chloro-1-propanol are 0.02 mg / L, 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, and 0.5 mg / L, respectively.

10. The method for analyzing the content of chloropropanol in hydroxypropyl modified starch according to claim 1, characterized in that: The GC-MS / MS analysis in step S4 includes the following parameters: Chromatographic temperature program: maintain at 50-70°C for 1-3 min, then increase to 210-230°C at a heating rate of 15-25°C / min and maintain for 1-3 min; Carrier gas: helium, purity ≥ 99.999%; Carrier gas flow rate: 0.5~1.5mL / min; Inlet temperature: 220~240℃; Injection volume: 1.0 μL; Injection mode: split injection, split ratio 4:1; Electron bombardment source: 70eV; Ion source temperature: 220~240℃; Mass spectrometer transmission interface temperature: 250~270℃; Mass spectrometry monitoring mode: multiple reaction monitoring.

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