Method for detecting low-molecular aldehyde substances in white spirit

Abstract

The invention relates to the technical field of Baijiu detection, and particularly provides a method for detecting low-molecular aldehyde substances in Baijiu. The detection method comprises the following steps: adding an isotope internal standard substance into a white spirit sample, carrying out water bath derivatization, adding sodium chloride into a sample solution to saturate the solution, adding an extracting agent in proportion, carrying out ultrasonic centrifugation, and dehydrating with anhydrous Na2SO4 to obtain a sample solution. The method comprises the following steps: preparing an aldehyde compound mixed standard solution by adopting a simulated matrix, and treating according to a white spirit sample pretreatment method to obtain a standard solution; and simultaneously injecting the sample solution and the standard solution into a gas chromatograph-mass spectrometer, and determining the mass concentration of each aldehyde compound in the sample solution by adopting an internal standard curve method. According to the method, various aldehyde compounds in the white spirit can be detected at the same time, detection errors caused by the difference between a standard solution and a sample matrix are eliminated, the detection limit of the method is 0.47 microgram / L-6. 10 microgram / L, and the method has the advantages of being high in specificity, low in detection limit, high in accuracy and stable in result.

Description

Technical Field

[0001] The invention relates to the technical field of liquor detection, and in particular to a method for detecting low-molecular aldehyde substances in liquor. Background Art

[0002] The composition of liquor flavor substances is extremely complex. Aldehyde compounds are important trace components in liquor. There are many ways to generate aldehyde compounds in liquor, such as alcohol oxidation, amino acid deamination and decarboxylation, keto acid decarboxylation, etc. Small molecule aldehyde substances have strong irritation and spicy taste, which can easily cause dizziness and dry mouth, and have a certain impact on the quality of liquor products.

[0003] There are many methods currently used to quantitatively detect aldehyde compounds in alcoholic beverages, including gas chromatography-mass spectrometry, derivatization agents combined with gas chromatography-mass spectrometry, and derivatization agents combined with high performance liquid chromatography.

[0004] The patent application with publication number CN201410107254.3 provides a method for quantifying 14 trans-2-enal and dienal compounds in liquor by HS-SPME-GC-MS using o-pentafluorobenzylhydroxylamine (PFBHA) derivatization. However, o-pentafluorobenzylhydroxylamine (PFBHA) is expensive and the solid phase microextraction method has poor repeatability.

[0005] The direct injection method of gas chromatography-mass spectrometry can be used to detect aldehyde compounds. Due to the strong polarity of aldehyde compounds, they are poorly separated on the chromatographic column and usually show tailing phenomenon, especially for low-boiling point and low-content aldehyde compounds. At the same time, they are easily interfered by other components in liquor, have poor repeatability and low accuracy. How to accurately detect low-molecular aldehyde substances in liquor has become one of the technical problems that need to be solved urgently. Summary of the invention

[0006] In view of this, the present invention proposes a method for detecting low molecular weight aldehyde compounds in liquor, aiming to improve the accuracy of detecting aldehyde compounds in liquor.

[0007] The technical solution of the present invention is implemented as follows: The present invention provides a method for detecting low molecular weight aldehyde substances in liquor, comprising the following steps:

[0008] Step 1: using a derivatizing agent to perform a derivatization reaction on a liquor sample to be tested containing an internal standard solution and a series of standard solutions containing a mixed aldehyde standard stock solution and an internal standard solution, wherein the derivatizing agent is 4-fluorobenzyloxyamine hydrochloride dissolved in ultrapure water;

[0009] Step 2: performing liquid-liquid microextraction on the liquor sample to be tested and the standard after the derivatization reaction to obtain a sample test solution and a standard test solution;

[0010] Step 3: using gas chromatography-mass spectrometry to measure the sample test solution and the standard test solution respectively;

[0011] Step 4: Prepare a standard curve with the chromatographic peak area ratio of the aldehyde compound derivatives to the internal standard derivatives in the standard test solution as the ordinate and the mass concentration ratio of the aldehyde compound to the internal standard as the abscissa; substitute the chromatographic peak area ratio of the aldehyde compound derivatives to the internal standard derivatives in the sample test solution measured in step 3 into the standard curve to calculate the mass concentration of the aldehyde compound in the liquor sample to be tested.

[0012] In some embodiments, the concentration of the derivatizing agent is 20 g / L.

[0013] In some embodiments, the internal standard liquid is hexanal-d 12 It is prepared by dissolving in 95% aldehyde-free ethanol. The concentration of the internal standard solution is 250 mg / L.

[0014] In some embodiments, the mixed aldehyde standard stock solution is prepared by dissolving formaldehyde, propionaldehyde, acrolein, isobutyraldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptanal, octanal, nonanal, and decanal standards in 95% aldehyde-free ethanol, and the concentration of the mixed aldehyde standard stock solution is 24.40-1556.80 mg / L.

[0015] The method of the present invention can detect one aldehyde compound in liquor, or can detect multiple aldehyde compounds at the same time. Preferably, when detecting one or more of the above 13 aldehyde compounds, the effect is better, that is, the detection repeatability is good, the sensitivity is high, and the result is more accurate.

[0016] In some embodiments, the preparation method of the standard series solution includes adding 95% aldehyde-free ethanol and purified water to prepare an ethanol solution with a volume fraction of 50%-60%, then adjusting the pH to 3-4 with lactic acid to obtain a simulated matrix, adding a mixed aldehyde standard stock solution to the simulated matrix, and then diluting the simulated matrix in 2.5 times to obtain a standard series solution.

[0017] In some embodiments, the derivatization reaction method includes heating the derivatization treatment in a water bath at 40-70° C. for 20-40 min.

[0018] In some embodiments, the specific steps of the derivatization reaction include diluting 2-4 mL of the liquor sample to be tested and the standard series solution with ultrapure water to an ethanol volume fraction of 10-15%, then adding 10-20 μL of the internal standard solution and 0.5-1 mL of the derivatization agent, and then heating the derivatization treatment in a 40-70°C water bath for 20-40 minutes.

[0019] In some embodiments, the liquid-liquid microextraction method includes adding sodium chloride to the derivatization solution until it is saturated, then adding the extraction solvent, the volume ratio of the saturated solution to the extraction solvent is 2:1, ultrasonic treatment in an ice bath for 20 minutes, centrifugation at 8000-10000 rpm for 5-10 minutes, standing overnight, taking the organic phase, adding anhydrous sodium sulfate to the organic phase for dehydration, and obtaining a sample test solution and a standard test solution.

[0020] In some embodiments, the extraction solvent is one or a mixture of ethyl acetate, dichloromethane, anhydrous ether, and n-pentane, preferably ethyl acetate.

[0021] In some embodiments, when establishing a standard curve, if the derivative product has cis and trans isomers, it is calculated as the sum of the two ion peak areas, and the peak area ratio of the aldehyde compound derivative to the internal standard derivative in the standard test solution is used as the ordinate, and the mass concentration ratio of the aldehyde compound to the internal standard in the standard test solution is used as the abscissa.

[0022] In some embodiments, the gas chromatography conditions are to use a (50% phenyl)-50% dimethylpolysiloxane capillary chromatographic column; the carrier gas is high-purity He (purity ≥99.999%), constant flow mode, and a flow rate of 1.0 mL / min; the temperature program is an initial temperature of 50°C, maintained for 2 minutes, increased to 200°C at 5°C / min, maintained for 8 minutes, and then increased to 250°C at 30°C / min, maintained for 5 minutes; the injection port temperature is 250°C, non-split mode, and the injection volume is 1 μL; the mass spectrometry conditions are an electron ionization source (electronionization, Extractor); electron energy 70 eV; ion source temperature 230°C; quadrupole temperature 150°C; mass spectrometry transmission line temperature 280°C.

[0023] In some embodiments, the mass concentration of the aldehyde compound is calculated as follows:

[0024]

[0025] Where:

[0026] C s : The mass concentration of aldehyde compounds in the liquor sample to be tested, in μg / L;

[0027] A s : The peak area of ​​aldehyde compound derivatives in the liquor sample to be tested;

[0028] A i : Peak area of ​​internal standard derivative;

[0029] C i : concentration of internal standard;

[0030] b: intercept value of the standard curve;

[0031] k: slope of the standard curve.

[0032] The present invention adopts an ethanol aqueous solution after adjusting the pH value as a simulated matrix to prepare a standard solution, and simultaneously uses a derivatizing agent to derivatize the standard solution and the sample into corresponding oximes, thereby improving the mass-to-charge ratio of the quantitative ion and reducing interference; further, a liquid-liquid microextraction method is used for extraction, and an isotope internal standard curve method is used for quantification, which can avoid interference from other components in the liquor and effectively avoid detection errors caused by the matrix effect.

[0033] The invention adopts gas chromatography-mass spectrometry to analyze and detect aldehyde compounds in liquor, which has the advantages of strong specificity, high sensitivity, large response value, small interference, rapidity and accuracy.

[0034] The present invention uses isotopes of aldehyde compounds as internal standards during sample pretreatment, which can reduce detection errors. In addition, since the carbonyl group in the aldehyde compound has extremely high reactivity, the C=O double bond can undergo a substitution reaction with the hydroxylamine compound to generate the corresponding oxime (C=NOH), thereby improving the mass-to-charge ratio of the quantitative ion, reducing interference, and increasing the accuracy of the quantitative result; the liquid-liquid microextraction method is adopted, and only a small amount of organic solvent is used for extraction, which greatly reduces the amount of organic solvent used, reduces costs, and reduces pollution to the environment.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention adopts gas chromatography-mass spectrometry to determine aldehyde compounds in liquor, adopts low-cost 4-fluorobenzyloxyamine hydrochloride to derive aldehyde compounds into corresponding oximes, and simultaneously uses isotopes with the same properties as the aldehyde compounds as internal standards, prepares a matrix similar to the liquor sample as a simulated matrix, and extracts the simulated matrix using the same pretreatment method as the liquor sample, and performs determination under the same instrument conditions, thereby eliminating the detection error caused by the matrix effect and ensuring the accuracy of the detection result. The method of the present invention can simultaneously detect a variety of aldehyde compounds in liquor, with a detection limit of 0.47μg / L-6.10μg / L, and has the advantages of wide application range, low detection limit, high specificity and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 The selected ion mass spectra of 13 aldehyde compound derivatives and the internal standard derivative in Example 1;

[0039] Figure 2 is the standard curve diagram of formaldehyde in Example 1;

[0040] Figure 3 is the standard curve diagram of propionaldehyde in Example 1;

[0041] Figure 4 is the standard curve diagram of acrolein in Example 1;

[0042] Figure 5 is the standard curve diagram of isobutyraldehyde in Example 1;

[0043] Figure 6 is the standard curve diagram of butyraldehyde in Example 1;

[0044] Figure 7 is the standard curve diagram of isovaleraldehyde in Example 1;

[0045] Figure 8 It is the standard curve diagram of 2-butenal in Example 1;

[0046] Fig. 9 is the standard curve diagram of valeraldehyde in Example 1;

[0047] Fig.10 It is the standard curve diagram of hexanal in Example 1;

[0048] Fig.11 is the standard curve diagram of heptanal in Example 1;

[0049] Fig.12 It is the standard curve diagram of octanal in Example 1;

[0050] Fig.13 is the standard curve diagram of nonanal in Example 1;

[0051] Fig.14 is the standard curve diagram of decanal in Example 1;

[0052] Fig.15 This is the selected ion mass spectrum of the light-flavor liquor sample in Example 1;

[0053] Fig.16 This is the selected ion mass spectrum of the recovery rate experiment of the light-fragrance liquor sample in Example 1;

[0054] Fig.17 It is the selected ion mass spectrum of the Luzhou-flavor liquor sample in Example 2;

[0055] Fig.18This is the selected ion mass spectrum of the Maotai-flavor liquor sample in Example 3;

[0056] Fig.19 This is the selected ion mass spectrum of the light-flavor liquor sample treated by the comparative method in Comparative Example 1;

[0057] Fig. 20 This is the selected ion mass spectrum of the light-fragrance liquor sample treated by the comparative method in Comparative Example 2. DETAILED DESCRIPTION

[0058] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0060] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0061] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0062] Example 1

[0063] This embodiment provides a method for detecting the mass concentration of low molecular weight aldehyde compounds in liquor (including formaldehyde, propionaldehyde, acrolein, isobutyraldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptanal, octanal, nonanal, and decanal), which is as follows:

[0064] 1. Reagents:

[0065] Aldehyde-free ethanol (95%), anhydrous ether, and n-pentane were of chromatographic grade; lactic acid, anhydrous Na2SO4, and NaCl were of analytical grade; water was ultrapure water;

[0066] Simulated matrix: Pipette 65 mL of aldehyde-free ethanol into a 100 mL volumetric flask, add about 0.2 mL of lactic acid aqueous solution (60.0 g / L), and dilute to the mark with ultrapure water to a pH of 3-4.

[0067] 20g / L derivatization agent: Weigh 2g of 4-fluorobenzyloxyamine hydrochloride, dissolve it in ultrapure water, transfer it to a 100mL volumetric flask, dilute to the mark, and mix well for later use.

[0068] 2. Test samples and aldehyde standards

[0069] Light-flavor liquor, alcohol content 60.1% vol;

[0070] Formaldehyde, propionaldehyde, acrolein, isobutylaldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptaldehyde, octanal, nonanal, decanal, hexanal-d 12 , purity greater than 97.8%, purchased from Shanghai Anpu Laboratory Technology Co., Ltd.

[0071] 3. Preparation of standard solution

[0072] 3.1 Mixed aldehyde standard stock solution

[0073] Accurately weigh appropriate amounts of 13 aldehyde compound standards into a 10 mL volumetric flask, dissolve them in aldehyde-free ethanol and make up to the mark to obtain a mixed standard stock solution of 13 aldehyde compounds, labeled as SS-1, and stored at -20 °C in the dark. The specific concentrations are shown in Table 1.

[0074] Table 1 Concentrations of 13 aldehyde compounds in mixed aldehyde standard stock solution

[0075]

[0076] 3.2 Standard solution series

[0077] Accurately pipette 0.2 mL of 13 mixed aldehyde standard stock solutions (SS-1) into a 10 mL volumetric flask, and dilute to the mark with simulated matrix to obtain 13 aldehyde standard solutions, labeled as HB1. Then, HB1 was diluted 2.5 times with simulated matrix to obtain HB2 to HB6, and a series of aldehyde standard solutions were obtained. Store at 4°C in the dark, with a shelf life of 1 month.

[0078] 3.3 Internal standard solution

[0079] Weigh 2.5 mg of hexanal-d 12 The standard was placed in a 10 mL volumetric flask and dissolved to volume with aldehyde-free ethanol to obtain a 250 mg / L internal standard solution, which was stored at -20 °C in the dark.

[0080] 4. Sample processing

[0081] 4.1 Derivatization of aldehyde compounds

[0082] Accurately pipette 4 mL of the light-flavor liquor sample and the standard series solutions (HB1-HB6) in step 3.2 into 50 mL centrifuge tubes, dilute the sample solution with ultrapure water to an ethanol volume fraction of 10%, add 20 μL of internal standard solution and 1 mL of derivatization agent, shake for 5 min, derivatize in a 60°C water bath for 30 min, take out, and cool to room temperature.

[0083] 4.2 Extraction of aldehyde derivatives

[0084] Add NaCl to the sample after derivatization with aldehyde compounds in step 4.1 until the solution is saturated, add 2 mL of ethyl acetate, shake for 5 min, ultrasonicate in an ice bath for 10 min, centrifuge at 8000 rpm for 5 min, let stand overnight, collect the lower organic phase in a brown injection vial, add anhydrous Na2SO4 for dehydration, and filter the resulting sample for GC-MS analysis.

[0085] 5. Sample determination

[0086] 5.1 Instrument conditions

[0087] GC conditions: Agilent 8890-5977B gas spectrometer; the stationary phase of the chromatographic column was a 50% phenyl / 50% dimethylpolysiloxane capillary column, with a column length of 30 m, an inner diameter of 0.25 mm, and a liquid film of 0.25 μm or a chromatographic column with equivalent performance; the carrier gas was high-purity He (purity ≥ 99.999%), in constant flow mode with a flow rate of 1.0 mL / min; the heating program was an initial temperature of 50°C, maintained for 2 min, increased to 200°C at 5°C / min, maintained for 8 min, and then increased to 250°C at 30°C / min, maintained for 5 min; the injection port temperature was 250°C, in splitless mode, and the injection volume was 1 μL;

[0088] MS conditions: electron ionization source (electron ionization, Extractor); electron energy 70eV; ion source temperature 230℃; quadrupole temperature 150℃; mass spectrometer transmission line temperature 280℃; first use GC-MS to perform a full scan (m / z 30-500) in SCAN mode to obtain a full scan mass spectrum, and optimize the instrument parameters to determine the retention time and characteristic ions of 13 aldehyde compound derivatives and internal standard derivatives, then group the compounds, and then use the selected ion mode scan (SIM) and use the internal standard method for quantification. The selected ion mass spectrum information of the 13 aldehyde compound derivatives and internal standard derivatives is shown in Table 2, and the mass spectrum is shown in the attached Figure 1 If the derivative product has cis-isomers and trans-isomers, it is calculated as the sum of the two ion peak areas.

[0089] Table 2 Quantitative information of 13 aldehyde compounds and internal standards

[0090]

[0091]

[0092] 5.2 Establishment of standard curve

[0093] Take the derivatized HB1-HB6 standard series solutions in step 4.2, and inject them into the GC-MS in order from low to high concentrations, monitor the mass spectra of the 13 aldehyde derivatives and the internal standard derivatives, and make a standard curve with the chromatographic peak area ratio of the aldehyde compound derivatives and the internal standard derivatives in the standard series solutions as the ordinate and the mass concentration of the aldehyde compound as the abscissa. The parameters of the standard curves of the 13 aldehyde compounds are shown in Table 3. The standard curves of the 13 aldehyde compounds are as follows: Figure 2 to Figure 14 As shown, Figure 1 The chromatographic peaks 1 to 13 are formaldehyde, propionaldehyde, acrolein, isobutylaldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptaldehyde, octanal, nonanal, and decanal, respectively. The chromatographic peak 14 is hexanal-d 12 (internal standard).

[0094] Table 3 Standard curve parameters of 13 aldehyde compounds

[0095] serial number Compound Slope / k Intercept / b <![CDATA[R 2 ]]> Concentration range / (μg / L) 1 Formaldehyde derivatives 5.0113 0.1877 0.9991 107.8～10529.0 2 Propionaldehyde derivatives 0.8482 0.1038 0.9952 62.0～6055.8 3 Acrolein derivatives 2.8513 0.0575 0.9973 12.0～1170.2 4 Isobutyraldehyde derivatives 25.386 0.6480 0.9999 125.0～12203.2 5 Butyraldehyde derivatives 55.4700 -0.5435 0.9994 8.5～833.0 6 Isovaleraldehyde derivatives 0.4747 0.0279 0.9998 318.8～31136.0 7 2-Butenal derivatives 26.4630 0.3079 0.9979 9.2～898.4 8 Valeraldehyde derivatives 1.6531 0.0458 0.9991 5.9～576.8 9 Hexanal derivatives 3.4794 0.1208 0.9981 62.8～6134 10 Heptaldehyde derivatives 15.7630 0.0813 0.9991 5.9～573.6 11 Octanal derivatives 1.9027 0.0074 0.9985 5.0～488.0 12 Nonanal derivatives 2.9899 -0.0015 0.9971 6.2～605.8 13 Decanal derivatives 6.8528 0.0150 0.9992 6.4～625.2

[0096] 5.3 Sample determination

[0097] The sample solution and the standard solution were measured under the same detection conditions, and the peak areas A i Peak area A of the internal standard derivative f Substitute into the standard curve and calculate the mass concentration X of the corresponding aldehyde compound in the sample iThe chromatogram of the light-flavor liquor sample to be tested is as follows: Fig.15 shown.

[0098] 5.4 Calculation

[0099] The contents of 13 aldehyde compounds in the liquor sample to be tested are calculated according to the following formula:

[0100]

[0101] Where:

[0102] C s ------Mass concentration of aldehyde compounds in the sample, in micrograms per liter (μg / L);

[0103] A s ------Peak area of ​​aldehyde derivatives in the sample;

[0104] A i ------Peak area of ​​internal standard derivative;

[0105] C i ------Mass concentration of internal standard;

[0106] b------The intercept value of the standard curve;

[0107] k------the slope of the standard curve.

[0108] The calculation result is expressed as the arithmetic mean of two independent determination results obtained under repeatability conditions, retained to 2 decimal places.

[0109] 6. Precision experiment

[0110] Take the derivatized HB4 solution in step 5.2 and repeat the injection 6 times. The RSD value of the precision test was calculated based on the peak area ratio of the 13 aldehyde compound derivatives and the internal standard derivative. The RSD values ​​were all less than 5%. The results are shown in Table 4.

[0111] Table 4 Precision experimental data results of 13 aldehyde compounds

[0112]

[0113]

[0114] 7. Repeatability Experiment

[0115] Accurately pipette 4 mL of the sample to be tested into a 50 mL centrifuge tube, a total of 6 portions, marked as S-1 to S-6, and treat the sample solution according to the above method, determine the content of aldehyde compounds, and calculate the repeatability of the determination results of 13 aldehyde compounds. The RSD values ​​are all less than 5%, indicating that the method has good repeatability. The specific results are shown in Table 5.

[0116] Table 5 Repeatability test data results of 13 aldehyde compounds

[0117]

[0118] 8. Limit of detection (LOD) and limit of quantification (LOQ)

[0119] The limit of detection (LOD) is the sample mass concentration corresponding to the signal intensity / baseline noise (S / N) = 3:1; the limit of quantification (LOQ) is the sample mass concentration corresponding to the signal intensity / baseline noise (S / N) = 10:1.

[0120] In this example, the detection limits (LOD) of the 13 aldehyde compounds were 0.47 μg / L to 6.10 μg / L, and the quantification limits (LOQ) were 1.58 μg / L to 20.34 μg / L. The specific calculation results are shown in Table 6.

[0121] Table 6 Calculation results of limit of detection (LOD) and limit of quantification (LOQ) for 13 aldehyde compounds

[0122] name S / N Concentration / (μg / L) LOD / (μg / L) LOQ / (μg / L) formaldehyde 6192.22 1684.60 0.82 2.72 Propionaldehyde 2201.92 968.90 1.32 4.40 Acrolein 345.20 702.10 6.10 20.34 Isobutyraldehyde 2015.76 1952.50 2.91 9.69 Butyraldehyde 842.09 133.30 0.47 1.58 Isovaleraldehyde 4540.71 4981.80 3.29 10.97 2-Butenal 229.27 143.80 1.88 6.27 Valeraldehyde 251.32 92.30 1.10 3.67 Hexanal 783.44 981.40 3.76 12.53 Heptanal 136.53 91.80 2.02 6.72 Octanal 153.87 78.10 1.52 5.08 Nonanal 279.14 96.90 1.04 3.47 Decanal 161.33 100.00 1.86 6.20

[0123] 9. Accuracy Experiment

[0124] Accurately pipette 4 mL of the sample to be tested into a 50 mL centrifuge tube and divide it into 3 groups, A, B, and C, with 3 portions in each group, for a total of 9 portions, marked as Group A (R1-1, R1-2, and R1-3), Group B (R2-1, R2-2, and R2-3), and Group C (R3-1, R3-2, and R3-3); take the mixed standard stock solution (SS-1) of 13 aldehyde compounds in step 3.1, add 30 μL SS-1 to Group A, add 40 μL SS-1 to Group B, and add 50 μL SS-1 to Group C; then refer to steps 4.1 and 4.2 for pretreatment to obtain the sample solution for GC-MS analysis. The selected ion mass spectrum of the accuracy experiment of the sample to be tested is shown in Figure 2. Fig.16 shown.

[0125] The peak areas of aldehyde compound derivatives and internal standard derivatives were substituted into the standard curve to calculate the content and recovery rate of each aldehyde compound. The recovery rates of the 13 aldehyde compounds were all greater than 85%, and the RSD values ​​were all less than 10%, indicating that the method had good accuracy. The specific calculation results are shown in Table 7.

[0126] Table 7 Accuracy test results of 13 aldehyde compounds

[0127]

[0128]

[0129] Example 2

[0130] This embodiment provides a method for detecting the content of aldehyde compounds (formaldehyde, propionaldehyde, acrolein, isobutylaldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptaldehyde, octanal, nonanal, decanal) in Luzhou-flavor liquor, which is as follows:

[0131] 1. Reagents: Same as in Example 1.

[0132] 2. Samples and standards to be tested

[0133] The sample to be tested is a Luzhou-flavor liquor with an alcohol content of 63.2% vol; the standard product is the same as that in Example 1.

[0134] 3. Preparation of standard solution: same as in Example 1.

[0135] 4. Sample processing

[0136] 4.1 Derivatization of aldehyde compounds

[0137] Accurately pipette 4 mL of Luzhou-flavor liquor sample and the standard series solutions (HB1-HB6) in step 3.2 into 50 mL centrifuge tubes, dilute the sample solution with ultrapure water to an ethanol volume fraction of 10%, add 20 μL of internal standard solution and 1 mL of derivatization agent, shake for 5 min, derivatize in a 60°C water bath for 30 min, take out, and cool to room temperature.

[0138] 4.2 Extraction of aldehyde derivatives

[0139] Add NaCl to the sample derived from aldehyde compounds in step 4.1 until the solution is saturated, add 2 mL of ethyl acetate, shake for 5 min, ultrasonicate in an ice bath for 20 min, centrifuge at 8000 rpm for 5 min, let stand overnight, collect the lower organic phase in a brown injection vial, add anhydrous Na2SO4 for dehydration, and filter the resulting sample for GC-MS analysis.

[0140] 5. Drawing of standard curve: same as Example 1.

[0141] 6. Sample determination

[0142] The determination conditions and methods are the same as those in Example 1. The selected ion mass spectrum of the obtained Luzhou-flavor liquor sample is as follows: Fig.17Substituting the peak areas of the aldehyde compound derivatives and the internal standard derivatives into the standard curve, the content of each aldehyde compound in the Luzhou-flavor liquor sample was calculated, as shown in Table 8.

[0143] Table 8 Contents of 13 aldehyde compounds in Luzhou-flavor liquor (μg / L)

[0144]

[0145] Example 3

[0146] The present embodiment provides a method for detecting the content of aldehyde compounds (formaldehyde, propionaldehyde, acrolein, isobutylaldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptaldehyde, octanal, nonanal, decanal) in Maotai-flavor liquor, which is as follows:

[0147] 1. Reagents: Same as in Example 1.

[0148] 2. Samples and standards to be tested

[0149] The sample to be tested is a Maotai-flavor liquor with an alcohol content of 53.2% vol; the standard product is the same as that in Example 1.

[0150] 3. Preparation of standard solution: same as in Example 1.

[0151] 4. Sample processing

[0152] 4.1 Derivatization of aldehyde compounds

[0153] Accurately pipette 4 mL of Maotai-flavor liquor sample and the standard series solutions (HB1-HB6) in step 3.2 into 50 mL centrifuge tubes, dilute the sample solution with ultrapure water to an ethanol volume fraction of 10%, add 20 μL of internal standard solution and 1 mL of derivatization agent, shake for 5 min, derivatize in a 60°C water bath for 30 min, take out, and cool to room temperature.

[0154] 4.2 Extraction of aldehyde derivatives

[0155] Add NaCl to the sample derived from aldehyde compounds in step 4.1 until the solution is saturated, add 2 mL of ethyl acetate, shake for 5 min, ultrasonicate in an ice bath for 20 min, centrifuge at 8000 rpm for 5 min, let stand overnight, collect the lower organic phase in a brown injection vial, add anhydrous Na2SO4 for dehydration, and filter the resulting sample for GC-MS analysis.

[0156] 5. Drawing of standard curve: same as Example 1.

[0157] 6. Sample determination

[0158] The determination conditions and methods are the same as those in Example 1. The selected ion mass spectrum of the obtained Maotai-flavor liquor sample is as follows: Fig.18 Substituting the peak areas of the aldehyde compound derivatives and the internal standard derivatives into the standard curve, the content of each aldehyde compound in the Maotai-flavor liquor sample was calculated, as shown in Table 9.

[0159] Table 9 Contents of 13 aldehyde compounds in Maotai-flavor liquor (μg / L)

[0160]

[0161] Comparative Example 1

[0162] Liquid-liquid microextraction combined with gas chromatography-mass spectrometry was used as a comparative method to determine aldehyde compounds in liquor. The specific steps are as follows:

[0163] Accurately transfer 4 mL of light-flavor liquor sample into a 50 mL centrifuge tube, dilute the sample solution with ultrapure water to an ethanol volume fraction of 10%, add 20 μL of internal standard solution, mix well, add NaCl until the solution is saturated, add 2 mL of ethyl acetate, shake for 5 min, ultrasonicate in an ice bath for 10 min, centrifuge at 8000 rpm for 5 min, let stand overnight, collect the lower organic phase into a brown injection vial, add anhydrous Na2SO4 for dehydration, and filter the obtained sample solution for GC-MS analysis. The selected ion mass spectrum of the obtained light-flavor liquor is shown in the figure below: Fig.19 shown.

[0164] The comparison results of Example 1 and Comparative Example 1 are shown in Table 9. The recovery rates of 13 aldehyde compounds in Example 1 were 86.54% to 104.11%, the relative standard deviation was 1.83% to 6.40%, and the detection limit was 0.47 μg / L to 6.10 μg / L. The recovery rates of 13 aldehyde compounds in Comparative Example 1 were 43.55% to 88.61.%, the relative standard deviation was 7.11% to 28.23%, and the detection limit was 5.22 μg / L to 91.63 μg / L, indicating that the accuracy and detection limit of the method provided by the present invention are better than those of the comparative method.

[0165] Table 9 Comparison results of accuracy experiments on 13 aldehyde compounds

[0166]

[0167] Comparative Example 2

[0168] This comparative example uses the method in application publication number CN201410107254.3 as a comparative method:

[0169] Take a sample of light-flavor liquor, dilute the sample with ultrapure water that has been boiled and cooled to room temperature to an ethanol volume fraction of 10%; accurately pipette 8 mL of the diluted liquor sample, place it in a 20 mL headspace bottle, add NaCl until the solution is saturated, add 20 μL of 176.5 mg / L internal standard p-fluorobenzaldehyde and 300 μL of derivatization reagent PFBHA solution, and tighten the bottle cap. Place the headspace bottle in an MPS2 incubator at 65°C for 5 minutes, extract at 65°C for 45 minutes, and desorb at 250°C for 5 minutes. The selected ion mass spectrum of the light-flavor liquor obtained is shown below: Fig. 20 shown.

[0170] The comparison results of Example 1 and Comparative Example 2 are shown in Table 10. In Example 1, the recovery rates of 13 aldehyde compounds were 86.54% to 104.11%, the relative standard deviation was 1.83% to 6.40%, and the detection limit was 0.47 μg / L to 6.10 μg / L. The recovery rates of 13 aldehyde compounds in Comparative Example 2 were 71.75% to 118.43%, the relative standard deviation was 7.75% to 16.23%, and the detection limit was 0.23 μg / L to 1.44 μg / L, indicating that the repeatability and accuracy of the method provided by the present invention are better than those of the comparative method.

[0171] Table 10 Comparison results of accuracy experiments on 13 aldehyde compounds

[0172]

[0173] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting low molecular weight aldehydes in liquor, characterized in that: include: Step 1: using a derivatizing agent to perform a derivatization reaction on a liquor sample to be tested containing an internal standard solution and a series of standard solutions containing a mixed aldehyde standard stock solution and an internal standard solution, wherein the derivatizing agent is 4-fluorobenzyloxyamine hydrochloride dissolved in ultrapure water; Step 2: performing liquid-liquid microextraction on the liquor sample to be tested and the standard after the derivatization reaction to obtain a sample test solution and a standard test solution; Step 3: using gas chromatography-mass spectrometry to measure the sample test solution and the standard test solution respectively; Step 4, prepare a standard curve with the chromatographic peak area ratio of the aldehyde compound derivative and the internal standard derivative in the standard test solution as the ordinate and the mass concentration ratio of the aldehyde compound and the internal standard as the abscissa; Substitute the chromatographic peak area ratio of the aldehyde compound derivative and the internal standard derivative in the sample test solution measured in step 3 into the standard curve to calculate the mass concentration of the aldehyde compound in the liquor sample to be tested.

2. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The concentration of the derivatizing agent was 20 g / L.

3. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The internal standard solution used was hexanal-d 12 It is prepared by dissolving in 95% aldehyde-free ethanol. The concentration of the internal standard solution is 250 mg / L.

4. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The mixed aldehyde standard stock solution is prepared by dissolving formaldehyde, propionaldehyde, acrolein, isobutyraldehyde, butyraldehyde, isovaleraldehyde, 2-butenal, valeraldehyde, hexanal, heptanal, octanal, nonanal, and decanal standard products in 95% aldehyde-free ethanol. The concentration of the mixed aldehyde standard stock solution is 24.40-1556.80 mg / L.

5. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The preparation method of the standard series solution includes: adding 95% aldehyde-free ethanol and purified water to prepare an ethanol solution with a volume fraction of 50%-60%, then adjusting the pH to 3-4 with lactic acid to obtain a simulated matrix, adding a mixed aldehyde standard stock solution to the simulated matrix, and then diluting the simulated matrix in 2.5 times to obtain a standard series solution.

6. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The derivatization reaction method includes heating the derivatization treatment in a water bath at 40-70° C. for 20-40 minutes.

7. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The liquid-liquid microextraction method includes adding sodium chloride to the derivatization solution to a saturated state, and then adding an extraction solvent, wherein the volume ratio of the saturated solution to the extraction solvent is 2:1, ultrasonically treating in an ice bath for 20 minutes, centrifuging for 5-10 minutes, standing overnight, taking an organic phase, and dehydrating the organic phase to obtain a sample test solution and a standard test solution.

8. The method for detecting low molecular weight aldehydes in liquor according to claim 7, characterized in that: The extraction solvent is one of ethyl acetate, dichloromethane, anhydrous ether and n-pentane or a mixture of two of them.

9. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The gas chromatography conditions were as follows: a (50% phenyl)-50% dimethylpolysiloxane capillary column; the carrier gas was high-purity He (purity ≥ 99.999%), in constant flow mode with a flow rate of 1.0 mL / min; the temperature program was an initial temperature of 50°C, maintained for 2 min, increased to 200°C at 5°C / min, maintained for 8 min, then increased to 250°C at 30°C / min, maintained for 5 min; the injection port temperature was 250°C, in splitless mode, and the injection volume was 1 μL; the mass spectrometry conditions were an electron ionization source (electron ionization, Extractor); electron energy was 70 eV; ion source temperature was 230°C; quadrupole temperature was 150°C; and mass spectrometry transmission line temperature was 280°C.

10. The method for detecting low molecular weight aldehydes in liquor according to claim 1, characterized in that: The calculation formula for the mass concentration of aldehyde compounds is: Where: C s : The mass concentration of aldehyde compounds in the liquor sample to be tested, in μg / L; A s : The peak area of ​​aldehyde compound derivatives in the liquor sample to be tested; A i : Peak area of ​​internal standard derivative; C i : concentration of internal standard; b: intercept value of the standard curve; k: slope of the standard curve.

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