Determination of individual carbon isotopes of trace substances in Maotai-flavor liquor

Abstract

The present invention relates to monomer carbon isotope (δ 13 C) analysis technology provides a novel monomer carbon isotope analysis method. This method uses gas chromatography (GC) to separate trace substances in Maotai-flavor liquor samples, then uses a conversion device to convert these substances into carbon dioxide (CO2), and finally uses a stable isotope ratio mass spectrometer (IRMS) to determine its monomer δ 13 The determination technology of the present invention not only provides the trace substances δ 13 The accuracy of C value measurement provides a scientific basis for identifying the authenticity of Maotai-flavor liquor, effectively curbing the counterfeiting of Maotai-flavor liquor on the market.

Description

Technical Field

[0001] The present invention relates to the field of analytical chemistry, in particular to a method for analyzing the carbon isotope content (δ 13 C) determination method, which provides a new scientific means for quality control and authenticity identification of Maotai-flavor liquor through advanced analytical technology. Background Art

[0002] Due to its complex process and microbial system, Maotai-flavor liquor contains a variety of trace components. According to literature reports, nearly a thousand components have been qualitatively and quantitatively detected in Maotai-flavor liquor. Among them, acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid and furfural are very important flavor components in Maotai-flavor liquor, with a total content of no more than 2%. Although studies have analyzed these flavor components, there has been no specific method for determining the single carbon isotope of trace substances in Maotai-flavor liquor. Most studies have only determined the carbon, hydrogen and oxygen isotopes of ethanol, with a single method and limited scope of application.

[0003] In the prior art, some documents (such as the isotope identification technology of solid-state liquor and solid-liquid liquor, and the determination of carbon stable isotopes of several important flavor substances in Luzhou-flavor liquor) have established carbon isotope ratios of specific substances in liquor, but these methods either do not point out the stability of the method, or are only applicable to specific types of liquor, such as Luzhou-flavor liquor, and the types of substances determined are limited, and are not applicable to Maotai-flavor liquor. Chinese patent CN114062556A discloses a method for detecting the carbon isotope composition of liquor flavor substances, but the patent does not provide a method for determining the monomer carbon isotope of furfural, a hallmark compound of Maotai-flavor liquor. Chinese patent CN103792300A discloses a detection method for identifying whether liquor is adulterated, but the patent does not provide qualitative analysis results, and there is a possibility of misjudgment of the target substance, and does not provide a method for determining the monomer carbon isotope of furfural, a hallmark compound of Maotai-flavor liquor.

[0004] The present invention aims to overcome the limitations of the prior art and provide a method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor, so as to improve the progress of Maotai-flavor liquor determination technology and provide a method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor. 13 The application of C value in the field of Maotai-flavor liquor identification provides technical support and effectively curbs the counterfeiting of Maotai-flavor liquor. Summary of the invention

[0005] (1) Problems to be solved

[0006] This aspect aims to solve the limitations of the existing methods for determining the carbon isotope of trace substances in Maotai-flavor liquor, and provides a method that does not require sample pretreatment, is simple, fast, accurate, and uses less sample. According to the physicochemical properties of Maotai-flavor liquor and the characteristics of gas chromatography-isotope mass spectrometry (GC-C-IRMS), the present invention achieves accurate and stable determination of the carbon isotope of various trace substances in Maotai-flavor liquor, promotes the progress of carbon isotope analysis technology of trace components in Maotai-flavor liquor, and provides a technical method for formulating detection standards.

[0007] (2) Specific solutions of the present invention

[0008] The present invention combines gas chromatography separation theory and isotope detection technology to achieve accurate determination of carbon isotopes of trace components in Maotai-flavor liquor. Specifically, the method for determining carbon isotopes of trace components in Maotai-flavor liquor of the present invention preferably:

[0009] The method comprises using a gas chromatograph (GC) to separate trace substances in the Maotai-flavor liquor sample, including at least one of acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, and furfural;

[0010] The Maotai-flavor liquor sample is directly injected without pre-treatment;

[0011] The gas chromatograph described therein is equipped with a highly polar capillary chromatographic column;

[0012] The GC working conditions are as follows: HP-INNOWAX chromatographic column (60m×0.25mm, 0.25μm), carrier gas is high-purity helium, constant flow mode, flow rate is 1.0-1.2mL / min; injection volume is 0.5-1.0μL, injection port temperature is 200-230°C; heating program is: heating to 55°C at 2.5°C / min, hold for 10min; heating to 118°C at 10.0°C / min, hold for 1.5min; heating to 123°C at 0.6°C / min, hold for 2min; heating to 240°C at 25°C / min, hold for 5min;

[0013] The stable isotope ratio mass spectrometer conditions are as follows: the ion source vacuum is 1.2×10 -6 mBr, voltage 2.996~3.06KV, current 1.5mA; the conversion device is GC Isolink; the operating temperature of the conversion device is 960~1060℃.

[0014] (3) Beneficial effects

[0015] The beneficial effects of the present invention are: 1) no sample pretreatment is required, saving time and cost, and improving detection efficiency; 2) it is capable of simultaneously determining the monomer δ of trace substances in 9 kinds of Maotai-flavor liquors. 13 C value, which improves the accuracy and efficiency of detection; 3) It is conducive to the advancement of Maotai-flavor liquor detection technology, reduces the cost of counterfeiting, and effectively curbs counterfeiting behavior; 4) It is a trace substance δ 13 The invention provides technical support for the application of C in the field of authenticity identification of Maotai-flavor liquor. The invention provides a new scientific detection method for domestic and foreign colleges and universities, research institutes and food testing institutions engaged in Maotai-flavor liquor analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Trace substance monomer δ in standard solution 13 GC-C-IRMS spectrum of C.

[0017] Figure 2 Trace substances in Maotai-flavor liquor samples 13 GC-C-IRMS spectrum of C. DETAILED DESCRIPTION

[0018] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0019] Example 1: Monomer δ of trace substances in standard solution 13 C value determination

[0020] 1. Instruments and reagents

[0021] Instruments: Delta V Advantage stable isotope ratio mass spectrometer (equipped with Trance GC), electronic balance, Milli-Q ultrapure water system preparation, 2 mL brown vials, pipettes, volumetric flasks.

[0022] Reagents: anhydrous ethanol, acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, furfural, all of chromatographic grade.

[0023] 2. Preparation of standard solution

[0024] Take anhydrous ethanol in a volumetric flask and prepare an ethanol-water solution (53:47, v / v). Use ethanol-water solution (53:47, v / v) to prepare single standard solutions of acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isoamyl alcohol, ethyl lactate, acetic acid, furfural and 9 mixed standard solutions.

[0025] 3. Sample determination

[0026] The standard solution was placed in a brown injection bottle and directly injected into the GC-C-IRMS for determination. The specific instrument parameters were as follows: HP-INNOWAX column (60m×0.25mm, 0.25μm), carrier gas was high-purity helium, constant flow mode, flow rate was 1.0mL / min; injection volume was 1.0μL, injection port temperature was 230℃; heating program was: heating to 55℃ at 2.5℃ / min, maintained for 10min; heating to 118℃ at 10.0℃ / min, maintained for 1.5min; heating to 123℃ at 0.6℃ / min, maintained for 2min; heating to 240℃ at 25℃ / min, maintained for 5min. Ion source vacuum was 1.2×10 -6 mBr, voltage 2.996KV, current 1.5mA; the conversion device is GCIsolink; the operating temperature of the conversion device is 1000℃.

[0027] 4. Result calculation

[0028] The sample was completely burned and converted into CO2 under high temperature of 1000℃ and oxygen conditions. GC-C-IRMS automatically detected the 44, 45, and 46 ion currents of acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, and furfural in the sample, and the δ 13 C value converted to the sample's δ 13 C value, and then according to the δ 13 C value converted to the sample's δ 13 C value.

[0029] 5. Results display

[0030] Depend on Figure 1 It is shown that under the determination conditions of the present invention, trace substances in the standard solution can be separated into individual monomers with excellent separation, and the order of peaks is acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid and furfural.

[0031] Repeated determination of δ10-100 of acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, and furfural in standard solutions 13 C, the results are shown in Table 1. As can be seen from Table 1, the method of the present invention repeatedly determines the δ 13 C, standard deviation SD are all less than 0.5‰, and repeatability limit are all less than 1.0‰, indicating that the method of the present invention has good stability and meets the measurement requirements.

[0032] Table 1 Trace substances in standard solutions δ 13 Repeated determination results of C (‰)

[0033]

[0034] Example 2: Monomer δ of trace substances in Maotai-flavor liquor samples 13 C value determination

[0035] 1. Instruments and reagents

[0036] Same as Example 1.

[0037] 2. Wine samples

[0038] The sample of Maotai-flavor liquor has an alcohol content of 53% vol.

[0039] 3. Quality Control

[0040] The measurement sequence was arranged according to a two-point standard drift correction mode: 2 standard solutions, 4 to 6 samples, 2 standard solutions, 4 to 6 samples, ... 2 standard solutions, 4 to 6 samples.

[0041] 4. Sample determination

[0042] According to the above method, the δ 13 C value, and then calibrate the trace substances in the wine sample according to the two-point standard drift correction mode 13 C value.

[0043] 5. Results display

[0044] Figure 2 The ion flow diagrams of 44, 45, and 46 of acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, and furfural in Maotai-flavor liquor under the determination conditions of the present invention are shown. Figure 2 The separation degree of each substance to be tested is excellent, and other trace substances are excluded from the substance to be tested. 13 C determination interference, meet the sauce-flavor liquor acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, furfural δ 13 Requirements for determination of C.

[0045] Table 2 Trace substances in Maotai-flavor liquor δ 13 Repeated determination results of C (‰)

[0046]

[0047] As shown in Table 2, the method of the present invention was used to repeatedly determine the δ 13The standard deviation SD is less than 0.5‰, and the repeatability limit is less than 1.0‰, indicating that the method of the present invention has good stability and the precision of the present method meets the requirements of trace substances in Maotai-flavor liquor, such as acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, furfural δ 13 Requirements for determination of C.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be covered by the scope of the claims of the present invention.

Claims

1. A method for determining the stable isotope composition of trace substances in Maotai-flavor liquor, characterized in that The following steps are involved: 1) Using gas chromatograph (GC) to separate trace substances in Maotai-flavor liquor samples; 2) converting the separated trace substances into carbon dioxide (CO2) through a conversion device; 3) Determination of the δ of the converted CO2 using a stable isotope ratio mass spectrometer (IRMS) 13 C value.

2. The method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor according to claim 1, characterized in that: The trace substances include at least one of acetaldehyde, ethyl acetate, n-propanol, isobutanol, n-butanol, isopentanol, ethyl lactate, acetic acid, and furfural.

3. The method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor according to claim 1, characterized in that: The Maotai-flavor liquor samples were directly injected into the gas chromatograph (GC).

4. The method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor according to claim 1, characterized in that: The gas chromatograph (GC) is equipped with a highly polar capillary column.

5. The method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor according to claim 1, characterized in that: The GC working conditions are as follows: using an HP-INNOWAX chromatographic column (60m×0.25mm, 0.25μm), the carrier gas is high-purity helium, the constant flow mode, the flow rate is 1.0-1.2mL / min; the injection volume is 0.5-1.0μL, and the injection port temperature is 200-230°C; the heating program is specifically as follows: starting temperature 40°C, heating to 55°C at 2.5°C / min, and holding for 10min; heating to 118°C at 10.0°C / min, and holding for 1.5min; heating to 123°C at 0.6°C / min, and holding for 2min; heating to 240°C at 25°C / min, and holding for 5min.

6. The method for determining the monomer carbon isotope of trace substances in Maotai-flavor liquor according to claim 1, characterized in that: The stable isotope ratio mass spectrometer (IRMS) was operated under the following conditions: ion source vacuum 1.2×10 -7 mbar, voltage 2.996~3.06KV, current 1.5mA; the conversion device is GC Isolink; the operating temperature of the conversion device is 960~1060℃.

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