Method for detecting sorbitol and mannitol in coated metal can packaged beverage

Abstract

The invention discloses a method for detecting sorbitol and mannitol in a coated metal can packaged beverage, which comprises the following steps of: performing solid-phase extraction on a coated metal can packaged beverage sample to be detected by using a polyamide solid-phase extraction small column, then adding water for elution, and receiving eluent; diluting with water, and filtering the membrane to obtain a test solution; and carrying out ultra-high performance liquid chromatography-mass spectrometry detection on the test solution. The method for detecting sorbitol and mannitol in the coated metal can packaged beverage is simple in pretreatment, high in accuracy and low in detection limit, provides good technical support for quality control and safety monitoring and supervision of food, food contact coating metal materials and products, and has good economic and social benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of food analysis, and more specifically, relates to a method for detecting sorbitol and mannitol in beverages packaged in coated metal cans. Background Art

[0002] Sorbitol is an important class of sugar alcohol compounds. Natural sources of sorbitol include apples, pears and other fruits and vegetables. Sorbitol can also be made by catalytic hydrogenation of glucose. Sorbitol can be used as an anti-caries sweetener, food antifreeze agent, etc. It can also be used clinically to treat cerebral edema, glaucoma, and edema and oliguria with normal heart and kidney function.

[0003] Mannitol and sorbitol are isomers, and the chirality of only one carbon atom is different between the two. The main sources of natural mannitol are kelp, mushrooms, seaweed, etc. Industrial mannitol is mainly produced by hydrogenation after glucose isomerization. Mannitol is mainly used as a clinical hyperosmotic antihypertensive drug and is rarely used in food.

[0004] GB 2760-2024 "National Food Safety Standard for the Use of Food Additives" stipulates that sorbitol can be used in a variety of foods such as beverages, dairy products, jams, and candies. Mannitol can be used in candies. Excessive intake of sorbitol can increase the burden on the gastrointestinal tract and cause digestive tract disorders. It may cause abdominal pain, diarrhea and other discomfort symptoms. It may also cause water and electrolyte disorders, abnormal insulin secretion, and allergic reactions. Common hazards of mannitol include allergic reactions, water and electrolyte disorders, etc.

[0005] GB 9685-2016 "National Food Safety Standard for the Use of Additives in Food Contact Materials and Articles" stipulates that sorbitol can be used in food contact plastics, adhesives, and paper products, but does not include mannitol. The European Consumer Health Protection Committee (CEPC) stipulates in "Coatings intended to come in contact with foodstuffs" (2009) that sorbitol and mannitol can be used in food contact coatings and coatings. Coated metal cans are an important form of beverage packaging. my country produces more than 47 billion aluminum cans for beer and beverages annually.

[0006] At present, there are some standard or literature methods that can be used to detect sorbitol and mannitol in foods, but they all have some defects. GB 5009.279-2016 provides a high-performance liquid chromatography method for the determination of xylitol, sorbitol, maltitol, and erythritol in foods (mannitol is not included). This method uses an amino chromatographic column or a cation exchange chromatographic column. For non-protein beverages, the pretreatment method is to dilute 5-fold with water and then filter through a membrane. The detection limit of sorbitol is 0.02 g / 100 g. SN / T 3142-2012 provides a liquid chromatography-mass spectrometry / mass spectrometry method for the determination of mannitol, maltose, xylitol, and sorbitol in exported foods. This method uses the electrospray negative ion mode and an Agilent ZORBAX sugar analysis column. For beverage samples, the pretreatment method is to dilute 10-fold with water and then filter through a membrane. This method cannot separate mannitol and sorbitol chromatographically, and it is difficult to achieve quantification when both are present. Hou Shaoping et al. established a determination method for 5 sugars and 3 sugar alcohols by high-performance liquid chromatography-single quadrupole mass spectrometry. This method uses an amide column (amide), and separates sorbitol and mannitol by adding guanidine hydrochloride and diethylamine to the mobile phase. However, the decomposition products of guanidine hydrochloride and diethylamine are all high-boiling components, which may damage the mass spectrometer and are not conducive to the actual implementation of the method. Summary of the Invention

[0007] Based on this, the purpose of the present invention is to provide a method for simultaneously detecting sorbitol and mannitol in beverages packaged in coated metal cans under conventional mobile phase conditions.

[0008] The technical solutions for achieving the above-mentioned invention purpose are as follows.

[0009] In the first aspect of the present invention, a method for detecting sorbitol and mannitol in beverages packaged in coated metal cans is provided, including the following steps:

[0010] (1) Transfer the beverage sample packaged in the coated metal can to be tested to a polyamide solid-phase extraction small column, then add water for elution, and collect the eluate; dilute with water and filter through a membrane to obtain the test solution.

[0011] (2) Perform ultra-high performance liquid chromatography-mass spectrometry detection on the test solution.

[0012] The chromatographic column used in the ultra-high performance liquid chromatography is a Hilic-Diol chromatographic column. Mobile phase A is 4 mmol / L ammonium acetate to 6 mmol / L ammonium acetate, and mobile phase B is acetonitrile. The gradient elution program is: 0 min → 5.0 min, 5% A; 5 min → 5.5 min, 5% A → 30% A; 5.5 min → 8.0 min, 30% A; 8 min → 8.5 min, 30% A → 5% A; 8.5 min → 12 min, 5% A.

[0013] The mass spectrometry uses the atmospheric pressure chemical ionization negative ion mode.

[0014] The second aspect of the present invention provides the application of the above detection method in the quality control of coated metal can packaging or the beverages contained therein.

[0015] In the present invention, when pretreating the sample, the beverage sample in the coated metal can to be detected is passed through a polyamide solid phase extraction column. When performing ultra-high performance liquid chromatography-mass spectrometry detection, a specific chromatographic column and gradient elution program are selected. At the same time, the atmospheric pressure chemical ionization negative ion mode is adopted, and other chromatographic conditions and mass spectrometry conditions are combined. Thus, sorbitol and mannitol in the beverage sample in the coated metal can to be detected can be well separated under conventional mobile phase conditions, without causing damage to the mass spectrometer, and with a small matrix effect, realizing the highly sensitive detection of sorbitol and mannitol.

[0016] When preparing the test sample solution in the present invention, the beverage sample in the coated metal can to be detected is subjected to solid phase extraction through a polyamide solid phase extraction column, which can effectively remove the pigments in the beverage sample (after passing through the polyamide solid phase extraction column, most of the original colored beverages lose their color and become colorless (cola, orange juice) or very light yellow (beer)), and the polyamide solid phase extraction column basically has no adsorption on sorbitol and mannitol in the beverage sample, and will not affect the recovery rates of sorbitol and mannitol in the beverage sample.

[0017] The method for detecting sorbitol and mannitol in the beverage in the coated metal can of the present invention has simple pretreatment, high accuracy, and low detection limit, providing good technical support for the quality control, safety monitoring, and safety supervision of foods, food-contact coated metal materials and products, and having good economic and social benefits. Description of the Drawings

[0018] Figure 1 It is the extracted ion chromatogram of sorbitol and mannitol in the standard working solution in Example 1 of the present invention.

[0019] Figure 2 It is the extracted ion chromatogram of sorbitol and mannitol in the beer sample in Example 3 of the present invention.

[0020] Figure 3 It is the extracted ion chromatogram of sorbitol and mannitol when detected using a PEI chromatographic column in Comparative Example 2 of the present invention.

[0021] Figure 4 It is the working curve of sorbitol and mannitol in the APCI+ ion mode in Comparative Example 4 of the present invention.

[0022] Figure 5Effect of different spray gas pressures on compound response in Comparative Example 5 of the present invention.

[0023] Figure 6 Effect of different curtain gas pressures on compound response in Comparative Example 5 of the present invention.

[0024] Figure 7 Effect of different ion source temperatures on compound response in Comparative Example 5 of the present invention.

[0025] Figure 8 Effect of different spray currents on compound response in Comparative Example 5 of the present invention.

[0026] Figure 9 Effect of different declustering voltages on compound response in Comparative Example 5 of the present invention.

[0027] Figure 10 Extracted ion chromatograms of cola-spiked samples detected using different product ions in Comparative Example 5 of the present invention. Detailed Description of the Invention

[0028] To facilitate understanding of the present invention, the present invention will be described more comprehensively below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0029] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0030] The experimental methods without specific conditions noted in the following examples are generally in accordance with conventional conditions or in accordance with the conditions recommended by the manufacturer. All common chemical reagents used in the examples are commercially available products.

[0031] In some embodiments of the present invention, a method for detecting sorbitol and mannitol in beverages packaged in coated metal cans is disclosed, including the following steps:

[0032] (1) Transfer a sample of the beverage packaged in a coated metal can to be tested to a polyamide solid-phase extraction cartridge, then add water for elution, and collect the eluate; after dilution with water and filtration through a membrane, the test solution is obtained;

[0033] (2) Perform ultra-high performance liquid chromatography-mass spectrometry detection on the test solution;

[0034] The chromatographic column used in the ultra-high performance liquid chromatography is a hydrophilic-diol (Hilic-Diol) chromatographic column. Mobile phase A is ammonium acetate at 4 mmol / L to 6 mmol / L, and mobile phase B is acetonitrile. The gradient elution program is as follows: 0 min → 5.0 min, 5% A; 5 min → 5.5 min, 5% A → 30% A; 5.5 min → 8.0 min, 30% A; 8 min → 8.5 min, 30% A → 5% A; 8.5 min → 12 min, 5% A;

[0035] The mass spectrometry uses the atmospheric pressure chemical ionization negative ion mode.

[0036] In some of these embodiments, the polyamide solid phase extraction cartridge in step (1) is a Poly-sery PA polyamide solid phase extraction cartridge with a specification of 500 mg / 6 mL.

[0037] In some of these embodiments, the mass spectrometry conditions in step (2) further include: spray current -3 μA to -4 μA, declustering voltage -80 V to -40 V, nebulizer gas pressure 40 psi to 50 psi, curtain gas pressure 35 psi to 45 psi, ion source temperature 300 °C to 400 °C.

[0038] In some of these embodiments, the declustering voltage is -80 V to -60 V, the nebulizer gas pressure is 40 psi to 45 psi, the curtain gas pressure is 40 psi to 45 psi, and the ion source temperature is 300 °C to 350 °C.

[0039] In some of these embodiments, the ultra-high performance liquid chromatography conditions in step (2) further include: injection volume 0.1 μL to 0.3 μL; column temperature: 28 °C to 32 °C; flow rate: 0.3 mL / min to 0.5 mL / min.

[0040] In some of these embodiments, the mass spectrometry conditions in step (2) further include: quantitative ion pairs 181.1>101.024 and 181.1>119.035, collision energy -30 V to -20 V, collision energy spread 8 V to 12 V.

[0041] In some of these embodiments, before step (1), there is also a step of performing ultrasonic degassing treatment on the beverage sample in the metal can with a coated package to be measured.

[0042] In some of these embodiments, the polyamide solid phase extraction cartridge in step (1) is a pre-activated polyamide solid phase extraction cartridge, and the activation step includes sequentially activating with 9 mL to 11 mL of methanol and 9 mL to 11 mL of water.

[0043] In some of these embodiments, the volume of the beverage sample in the coated metal can to be tested loaded onto the column in step (1) is 0.9 mL to 1.1 mL, and the volume of the eluting water is 1.8 mL to 2.2 mL.

[0044] In some of these embodiments, the dilution factor in step (1) is 18 to 22 times.

[0045] In some other embodiments of the present invention, the application of the above detection method in the quality control of coated metal can packaging or the beverages contained therein is disclosed.

[0046] In some of these embodiments, the beverage in the coated metal can is a non-alcoholic beverage (cola, orange juice) or an alcoholic beverage (such as beer).

[0047] In the following examples, the polyamide solid-phase extraction cartridge used is the Poly-sery PA polyamide solid-phase extraction cartridge from CNW Technologies GmbH, Germany, with a specification of 500 mg / 6 mL; the chromatographic column is the ChromCore Hilic Diol 100 mm×2.1 mm, 3 μm chromatographic column from ChromCore; the ultra-high performance liquid chromatography is the Aquity UPLC H-Class Plus from Waters Corporation; the quadrupole time-of-flight mass spectrometer is the X500B from Sciex.

[0048] The present invention will be described in detail below in conjunction with the accompanying drawings and specific examples.

[0049] Example 1 A method for detecting sorbitol and mannitol in beverages packaged in coated metal cans

[0050] It includes the following steps:

[0051] 1. Prepare the standard working solution

[0052] ① Standard stock solution (10 mg / mL): Accurately weigh 100 mg (accurate to 0.01 mg) of D-sorbitol (CAS 50-70-4, Macklin, 98.0%) and D-mannitol (CAS 69-65-8, Macklin, 99%) into a 10 mL volumetric flask respectively, dissolve with water, make up to the mark, shake well, transfer to a reagent bottle, and store at -20°C to obtain the individual standard stock solutions of sorbitol and mannitol.

[0053] ② Mixed standard intermediate solution 1 (1 mg / mL): Pipette 1 mL of each individual standard stock solution into a 10 mL volumetric flask respectively, make up to the mark with water, shake well, transfer to a reagent bottle, and store at -20°C.

[0054] ③Mixed standard intermediate solution 2 (10 mg / L): Pipette 1 mL of the individual standard stock solution into a 100 mL volumetric flask, make up to the mark with water, shake well, transfer to a reagent bottle, and store at -20 °C.

[0055] ④Standard working solutions: Accurately pipette 0.20 mL, 0.50 mL, 0.75 mL, 1.00 mL, 2.00 mL, and 3.00 mL of the mixed standard intermediate solution 2 into six 10 mL volumetric flasks respectively, make up to the mark with water, shake well, and prepare before use. The concentrations of the corresponding target substances in each standard working solution are 0.20 mg / L, 0.50 mg / L, 0.75 mg / L, 1.00 mg / L, 2.00 mg / L, and 3.00 mg / L respectively.

[0056] 2. Preparation of test sample solution and blank test solution

[0057] Transfer the beverage to be tested to a wide-mouth reagent bottle, place it in an ultrasonic cleaner, perform ultrasonic degassing for 15 min, and take it out. Pipette 1.00 mL of the ultrasonically degassed sample into a polyamide solid-phase extraction small column pre-activated (activated successively with 10 mL of methanol and 10 mL of water, which is a conventional method in this field), add 2.00 mL of water for elution, collect the eluate, and vortex mix. Take 0.50 mL of the eluate into a 10 mL graduated tube, make up to the mark with water, and vortex mix. Take about 1 mL of the solution and filter it through a 0.22 μm aqueous filter membrane into a vial to obtain the test sample solution.

[0058] Prepare the blank test solution using the same method.

[0059] 3. Detection by ultra-high performance liquid chromatography - quadrupole time-of-flight mass spectrometer

[0060] Detect the standard working solutions, blank test solutions, and test sample solutions on the instrument respectively to obtain the original data.

[0061] ①Liquid chromatography conditions include:

[0062] Chromatographic column: ChromCore Hilic Diol 100 mm × 2.1 mm, 3 μm;

[0063] Column temperature: 30 °C;

[0064] Injection volume: 0.2 μL;

[0065] Mobile phase A: 5 mmol / L ammonium acetate;

[0066] Mobile phase B: Acetonitrile;

[0067] Flow rate: 0.4 mL / min;

[0068] Gradient elution program: 0 min → 5.0 min, 5% A; 5 min → 5.5 min, 5% A → 30% A; 5.5 min → 8.0 min, 30% A; 8 min → 8.5 min, 30% A → 5% A; 8.5 min → 12 min, 5% A;

[0069] ② Mass spectrometry conditions include (atmospheric pressure chemical ionization source):

[0070] Ion source temperature: 350 °C;

[0071] Spray current: -3 μA

[0072] Spray gas: 40 Psi;

[0073] Curtain gas: 40 Psi

[0074] Mass spectrometry scan mode: high resolution multiple reaction monitoring (MRMHR);

[0075] Parent ion (m / z): 181.1

[0076] Daughter ion scan range (m / z): 50 - 120;

[0077] Collision energy: -25 V;

[0078] Collision energy spread: 10 V

[0079] Extracted ion (m / z): 101.024 (quantitative ion), 119.035 (qualitative ion).

[0080] 4. Result analysis

[0081] Quantitative ion extracted ion chromatogram of the standard working solution Figure 1 as shown

[0082] The standard working curve, correlation coefficient, linear range and signal-to-noise ratio are shown in Table 1.

[0083] Table 1 Standard working curve, correlation coefficient and linear range

[0084]

[0085] The ratio of the retention time of the chromatographic peak of the analyte in the test solution to that in the standard working solution should have a deviation within ±5%.

[0086] Based on the chromatographic peak areas of the blank test solution and the test solution, the content of sorbitol or mannitol in the analyte injection solution is obtained from the standard working curve, and then calculated according to formula (1) to obtain the content of sorbitol or mannitol in the test solution.

[0087]

[0088] In the formula:

[0089] X—the content of the analyte (sorbitol or mannitol) in the test sample, mg / L;

[0090] c1—the content of the analyte in the solution of the test sample for machine analysis obtained from the standard working curve, mg / L;

[0091] c0—the content of the analyte in the solution of the blank sample for machine analysis obtained from the standard working curve, mg / L;

[0092] V1—the sampling volume of the sample, mL (1 mL);

[0093] V2—the volume of the eluent, mL (2 mL);

[0094] f—the dilution factor, 20.

[0095] Example 2 Methodological Verification of the Detection Method of the Present Invention

[0096] This example verified the accuracy, precision and detection limit of the detection method of the present invention.

[0097] Samples of cola, orange juice and beer packaged in coated metal cans were processed according to the method of Example 1, and different masses of standard products were added to the samples. Each added concentration point was measured in parallel 6 times. The accuracy and precision of the method were obtained through the standard addition recovery rate and relative standard deviation.

[0098] The recovery rates of sorbitol and mannitol at different concentrations are shown in Tables 2 and 3.

[0099] Table 2 Recovery Rates of Added Sorbitol

[0100]

[0101] Table 3 Recovery Rates of Added Mannitol

[0102]

[0103] As can be seen from Tables 2 and 3, the recovery rates of added sorbitol and mannitol are between 73.7% and 104%, and the RSDs are between 2.4% and 6.0%, indicating good accuracy and precision.

[0104] The detection limit of the method was obtained based on the signal-to-noise ratio of the spiked solution. The detection limit of the method (S / N≥3) could reach 4 mg / L.

[0105] Example 3 Determination of the Contents of Sorbitol and Mannitol in Actual Samples

[0106] Using the detection method of Embodiment 1 of the present invention, sorbitol and mannitol in cola, orange juice and beer packed in coated metal cans purchased from a supermarket were detected.

[0107] The results are shown in Table 4.

[0108] Table 4 Content of sorbitol in beverages packed in coated metal cans (n = 6)

[0109]

[0110] Table 5 Content of mannitol in beverages packed in coated metal cans (n = 6)

[0111]

[0112] It can be seen from the results of Table 4 and Table 5 that there is no sorbitol and mannitol in the purchased cola and orange juice packed in coated metal cans, while the purchased beer packed in coated metal cans contains sorbitol and mannitol. Among them, the quantitative ion extraction ion chromatography of the beer sample is Figure 2 as shown.

[0113] Comparative Example 1

[0114] This comparative example compared the adsorption of two pretreatment methods on the beverage to be tested.

[0115] Method 1 (same as Embodiment 1): Transfer the beverage sample packed in the coated metal can to be tested to a wide-mouth reagent bottle, place it in an ultrasonic cleaner, perform ultrasonic degassing for 15 min, and take it out. Pipette 1.00 mL of the sample treated by ultrasonic degassing into a polyamide small column pre-activated (activated successively with 10 mL of methanol and 10 mL of water, which is a conventional method in the art), add 2.00 mL of water for elution, collect the eluate, and vortex mix.

[0116] Method 2: Pipette 1.00 mL of the beverage sample into a 10 mL centrifuge tube containing 50 mg of coconut shell activated carbon, vortex for 1 min, centrifuge at 4000 rpm, remove the upper layer of liquid, add 5 mL of water again, soak at 95 °C for 1 hour, filter the soaking solution through a filter membrane while it is hot, and detect the content of sorbitol and mannitol in the soaking solution.

[0117] When using Method 1 to treat the samples to be tested such as cola, orange juice, and beer, the pigments are basically retained on the small column. After treating the 20 mg / L standard working solution according to Method 1 and then performing subsequent detection according to the method of Embodiment 1, the recoveries of the two analytes of sorbitol and mannitol are about 100% and 99%. This result proves that the polyamide small column has basically no adsorption effect on sorbitol and mannitol.

[0118] After treating the 4 mg / L standard working solution with Method 2 and then detecting the soaking solution according to the instrumental method of Example 1, the recovery rates of both sorbitol and mannitol, the two analytes, were less than 50%. It can be seen that coconut shell activated carbon will have irreversible adsorption on sorbitol and mannitol. Therefore, the pretreatment method using coconut shell activated carbon is not suitable for detecting sorbitol and mannitol.

[0119] Comparative Example 2

[0120] This comparative example compared the effects of three chromatographic columns on the simultaneous detection of sorbitol and mannitol.

[0121] 1. The preparation method of the test solution was the same as that in Example 1.

[0122] 2. Detection by ultra-high performance liquid chromatography - quadrupole time-of-flight mass spectrometer

[0123] The standard working solution (2 mg / L) was detected using three chromatographic columns, ChromCore Hilic Diol (100 mm × 2.1 mm, 3 μm), Welch Hilicamide (100 mm × 2.1 mm, 3 μm); HYPERSIL GOLD Hilic PEI (100 mm × 2.1 mm, 1.9 μm) respectively, and other conditions were the same as those in Example 1.

[0124] The results showed that the two compounds could not be separated at all using the Welch Hilic amide chromatographic column. Compared with using the ChromCore Hilic Diol chromatographic column, using the HYPERSIL GOLD Hilic PEI chromatographic column had a better separation effect on the two compounds. See the chromatogram of the standard working solution in Figure 3 .

[0125] However, when detecting actual samples, the matrix effect of the HYPERSIL GOLD Hilic PEI chromatographic column was very obvious. In cola (n = 6), the absolute recovery rate of sorbitol was only about 55%; in orange juice (n = 6), the absolute recovery rate of mannitol was also only about 55%.

[0126] Therefore, both the Welch Hilic amide and HYPERSIL GOLD Hilic PEI chromatographic columns are not suitable for simultaneously detecting sorbitol and mannitol.

[0127] Comparative Example 3

[0128] This comparative example compared the effects of two mobile phases A on the simultaneous detection of sorbitol and mannitol.

[0129] 1. The preparation method of the test solution was the same as that in Example 1.

[0130] 2. Detection by ultra - performance liquid chromatography - quadrupole time - of - flight mass spectrometry

[0131] The standard working solution (2 mg / L) was detected using two mobile phases A (5 mmol / ammonium acetate, methanol + water = 1 + 9) respectively, and other conditions were the same as those in Example 1.

[0132] The results showed that under the two mobile phases, the separation effects of the two compounds were similar. However, compared with using methanol + water = 1 + 9 as mobile phase A, when using 5 mmol / ammonium acetate as mobile phase A, the response of the compounds doubled.

[0133] Comparative Example 4

[0134] This comparative example compared the effects of different ion sources and ionization modes on the simultaneous detection of sorbitol and mannitol.

[0135] 1. The preparation method of the test solution was the same as that in Example 1.

[0136] 2. Detection by ultra - performance liquid chromatography - quadrupole time - of - flight mass spectrometry

[0137] Four ion sources and ionization modes (electrospray ionization negative mode (ESI -), electrospray ionization positive mode (ESI +), atmospheric pressure chemical ionization negative mode (APCI -), atmospheric pressure chemical ionization positive mode (APCI +)) were used to detect cola samples (n = 6) respectively, and other conditions were the same as those in Example 1.

[0138] The results showed that the matrix effect of mannitol in cola samples was 41% in ESI + and 61% in ESI -. For APCI +, due to source fragmentation, the response showed a quadratic curve ( Figure 4 ).

[0139] Therefore, only APCI - is suitable as the ionization mode for the simultaneous detection of mannitol and sorbitol.

[0140] Comparative Example 5

[0141] This comparative example compared the effects of different mass spectrometry parameters on the simultaneous detection of sorbitol and mannitol.

[0142] 1. Spray gas pressure

[0143] (1) The preparation method of the test solution was the same as that in Example 1.

[0144] (2) Detection by ultra - performance liquid chromatography - quadrupole time - of - flight mass spectrometry

[0145] The standard working solution (2 mg / L) was detected using three kinds of spray gas pressures (40 Psi, 50 Psi, 60 Psi) respectively, and other conditions were the same as those in Example 1.

[0146] The results are shown in Figure 5 , and the results show that the response of the compound decreased significantly under the spray gas pressure of 60 Psi, and the responses of the compound under the sprayer pressures of 40 Psi and 50 Psi were close.

[0147] 2. Curtain gas pressure

[0148] (1) The preparation method of the test solution was the same as that in Example 1.

[0149] (2) Detection by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometer

[0150] The standard working solution (2 mg / L) was detected using four kinds of curtain gas pressures (30 Psi, 35 Psi, 40 Psi, 45 Psi) respectively, and other conditions were the same as those in Example 1.

[0151] The results are shown in Figure 6 , and the results show that when the curtain gas was at 35 Psi - 45 Psi, the response of the compound was significantly higher than that when the curtain gas was at 30 Psi.

[0152] 3. Ion source temperature

[0153] (1) The preparation method of the test solution was the same as that in Example 1.

[0154] (2) Detection by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometer

[0155] The standard working solution (2 mg / L) was detected using three kinds of ion source temperatures (400 °C, 350 °C, 300 °C) respectively, and other conditions were the same as those in Example 1.

[0156] The results are shown in Figure 7 , and the results show that the responses of the compound were all relatively high at the three ion source temperatures, and the response of the compound reached the highest at 350 °C.

[0157] 4. Spray current

[0158] (1) The preparation method of the test solution was the same as that in Example 1.

[0159] (2) Detection by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometer

[0160] The standard working solution (2 mg / L) was detected using three kinds of spray currents (-2 μA, -3 μA, -4 μA) respectively, and other conditions were the same as those in Example 1.

[0161] The results are shown in Figure 8 , and the results show that when the spray gas flow rates are -3 μA and -4 μA, the compound responses are significantly improved. Although the compound response is the highest at -4 μA, a smaller spray current is beneficial to the long-term stability of the instrument operation. Therefore, the optimal spray gas flow rate is -3 μA.

[0162] 5. Desolvation voltage

[0163] (1) The preparation method of the test solution is the same as that in Example 1.

[0164] (2) Detection by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry

[0165] The standard working solution (2 mg / L) was detected using three desolvation voltages (-80 V, -60 V, -40 V) respectively, and other conditions were the same as those in Example 1.

[0166] The results are shown in Figure 9 , and the results show that when the desolvation voltage is -60 V, the compound response is the highest.

[0167] 6. Monitoring ion pairs

[0168] Both sorbitol and mannitol can produce daughter ions such as 59.01, 71.01, 73.03, 85.03, 89.02, 101.02, 113.02, 119.04 from their precursor ions. In the SN / T 3142-2012 standard and some existing literature, the commonly used ion pairs for mannitol and sorbitol are 181>89, 181>71, 181>101. The inventors used 71.01 and 101.02 as daughter ions to detect the cola spiked sample (20 mg / L) (the test solution and other detection conditions were the same as those in Example 1), and the extracted ion chromatogram is shown in Figure 10 , as can be seen from Figure 10 , there are significantly more interfering peaks for the 71.01 daughter ion, which is not suitable as the daughter ion for detecting sorbitol and mannitol.

[0169] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0170] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for detecting sorbitol and mannitol in beverages packaged in coated metal cans, characterized in that: The following steps are involved: (1) Pipette a sample of a beverage packaged in a coated metal can to be tested onto a polyamide solid phase extraction column, add water for elution, and receive the eluate; Dilute with water and filter through the membrane to obtain the test solution; (2) subjecting the test solution to ultra-high performance liquid chromatography-mass spectrometry; The chromatographic column used in the ultra-high performance liquid chromatography is a Hilic-Diol chromatographic column, the mobile phase A is 4 mmol / L to 6 mmol / L ammonium acetate, the mobile phase B is acetonitrile, and the gradient elution program is: 0 min→5.0 min, 5% A; 5 min→5.5 min, 5% A→30% A; 5.5 min→8.0 min, 30% A; 8 min→8.5 min, 30% A→5% A; 8.5 min→12 min, 5% A; The mass spectrometry was performed using atmospheric pressure chemical ionization negative ion mode.

2. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to claim 1, characterized in that: The polyamide solid phase extraction column in step (1) is a Poly-sery PA polyamide solid phase extraction column.

3. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to claim 1, characterized in that: The mass spectrometry conditions in step (2) also include: spray current -3μA to -4μA, declustering voltage -80V to -40V, spray gas pressure 40psi to 50psi, curtain gas pressure 35psi to 45psi, and ion source temperature 300℃ to 400℃.

4. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to claim 3, characterized in that: The declustering voltage is -80V to -60V, the spray gas pressure is 40psi to 45psi, the curtain gas pressure is 40psi to 45psi, and the ion source temperature is 300°C to 350°C.

5. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to claim 3, characterized in that: The mass spectrometry conditions in step (2) also include: quantitative ion pairs 181.1>101.024 and 181.1>119.035, collision energy -30V to -20V, and collision energy extension 8V to 12V.

6. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to claim 1, characterized in that: The ultra-high performance liquid chromatography conditions in step (2) also include: injection volume 0.1 μL to 0.3 μL; column temperature: 28° C. to 32° C.; flow rate: 0.3 mL / min to 0.5 mL / min.

7. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to any one of claims 1 to 6, characterized in that: Before step (1), the method further includes subjecting the coated metal can packaged beverage sample to ultrasonic degassing treatment.

8. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to any one of claims 1 to 6, characterized in that: The polyamide solid phase extraction column in step (1) is a pre-activated polyamide solid phase extraction column, and the activation step comprises sequentially using 9 mL to 11 mL of methanol and 9 mL to 11 mL of water for activation.

9. The method for detecting sorbitol and mannitol in beverages packaged in coated metal cans according to any one of claims 1 to 6, characterized in that: In step (1), the column volume of the coated metal can packaged beverage sample to be tested is 0.9 mL to 1.1 mL, the volume of the eluted water is 1.8 mL to 2.2 mL, and the dilution multiple is 18 to 22 times.

10. Use of the detection method according to any one of claims 1 to 9 in quality control of coated metal can packaging or beverages contained therein.

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