Rapid detection method for butyric acid and isomeride thereof in Baijiu

Abstract

The invention discloses a method for rapidly detecting butyric acid and isomeride thereof in baijiu, which comprises the following steps of: directly adding 0.5-3ml of baijiu sample into a sampling bottle of a rapid gas chromatography-PTR photochemical ionization source-time-of-flight mass spectrometer without any pretreatment process and a large amount of organic solvent; appropriate rapid gas chromatography-mass spectrometry conditions are selected, and rapid gas chromatography-PTR photochemical ionization source-time-of-flight mass spectrometry is utilized to rapidly complete detection of butyric acid and isomeride thereof in Baijiu. According to the method established by the invention, the sample does not need any pretreatment process or a large amount of organic solvents, the butyric acid and the isomeride thereof in the Baijiu can be rapidly detected within five minutes, and a powerful means is provided for adjusting the acidity and taste of the Baijiu.

Description

Technical Field

[0001] The invention belongs to the field of analytical chemical instruments, and particularly relates to a method for rapid detection of butyric acid and its isomers in liquor. Background Art

[0002] Butyric acid is a colorless, transparent liquid with a certain pungent smell and taste. It is an organic acid that is commonly used in food, medicine, cosmetics and industrial fields. In light-flavor liquor, the role of butyric acid is to increase the acidity and taste of the liquor. Under normal circumstances, the acidity of light-flavor liquor is usually between 0.2% and 0.5%. Butyric acid can keep the acidity within a suitable range and improve the taste of the liquor. Butyric acid is an important acidity regulator. In light-flavor liquor, it can control the acidity of the liquor, adjust the taste of the liquor, improve its taste balance and smoothness, make it more lubricated, and feel more comfortable when entering the mouth. GC-MS is often used to detect butyric acid. However, in actual regulation, because liquor contains a variety of complex organic and inorganic matrices, including alcohols, acids, esters, aldehydes, ketones, furans, pyrazines, aromatics and phenols, it needs to be purified and enriched before processing. The complex pretreatment is time-consuming and affects the repeatability of the quantitative results. Therefore, it is necessary to develop highly sensitive, rapid and efficient detection methods for the detection of butyric acid and its isomers.

[0003] Soft ionization mass spectrometry can obtain molecular ions or quasi-molecular ions of the analyte, and has the advantages of simple spectra and easy analysis. It can realize rapid analysis of complex gases without or with only simple sample pretreatment. The core of soft ionization mass spectrometry is the soft ionization source. The mainstream soft ionization sources are high pressure photoionization (HPPI) and proton transfer reaction ionization (PTRCI). The working pressure (102Pa) of both is higher than the EI source (10-3Pa) used in GC-MS, and they have a higher molecular number density in the source. The detection sensitivity can reach the ppt-ppb level. Among them, HPPI is suitable for the analysis of aromatic compounds, furans, pyrazines, phenols and other compounds with high photoionization cross sections, while PTRCI has a better ionization effect on compounds with high proton affinity, such as alcohols, acids, aldehydes, ketones, esters and other compounds.

[0004] In view of this, the present invention discloses a rapid detection method for butyric acid and its isomers in liquor. The method does not require a pretreatment process, directly takes a certain amount of liquor sample and adds it into a sample bottle, and uses a rapid gas chromatography-PTR photochemical ionization source-time of flight mass spectrometry to quickly complete the detection of butyric acid and its isomers in liquor. Butyric acid isomers are not limited to isobutyric acid, isopentanol, ethyl acetate, 3-hydroxy-2-butanone, etc., which provides a powerful means for adjusting the acidity and taste of liquor. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a rapid detection method for butyric acid and its isomers in liquor. The method uses rapid gas chromatography-PTR photochemical ionization source-time of flight mass spectrometry, sets appropriate detection conditions, and can complete the detection of butyric acid and its isomers in liquor within five minutes. A rapid detection method for butyric acid and its isomers in liquor of the present invention does not require any pretreatment process and a large amount of organic solvent. A certain amount of liquor sample is directly taken and added to the injection bottle, and appropriate rapid gas chromatography-mass spectrometry conditions are selected. Rapid gas chromatography-PTR photochemical ionization source-time of flight mass spectrometry is used to complete the detection of butyric acid and its isomers in liquor within five minutes. Butyric acid isomers are not limited to isobutyric acid, acetic acid, isopentanol, ethyl acetate, 3-hydroxy-2-butanone, acetaldehyde, etc., which provides a powerful means for adjusting the acidity and taste of liquor.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A rapid detection method for butyric acid and its isomers in liquor comprises the steps of directly taking 0.5-3 ml liquor sample and adding it into a sample injection bottle of a rapid gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer, selecting appropriate detection conditions, and utilizing rapid gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer to complete the detection of butyric acid and its isomers in liquor.

[0008] When fast gas chromatography-PTR photochemical ionization source-time-of-flight mass spectrometer is used for testing, the temperature of the fast gas chromatography inlet is 150-240°C, the carrier gas is high-purity helium (He), the flow rate is 0.8-5 mL / min, the split ratio is 10:1, the polar chromatographic column is a DB-WAX chromatographic column, and the fast gas chromatography adopts a fast program heating mode. The heating program is an initial temperature of 100-140°C, maintained for 0.5-2.5 min, and then increased to 140-200°C at 10-30°C / min, and maintained for 0.2-5 min. The equilibrium temperature of the headspace injection device is 40-80°C; the sampling needle temperature is 60-100°C, the cleaning time is 0.5-1.0 min; the quantitative loop temperature is 80-150°C, the volume is 1-5 mL, the injection time is 0.3-1.0 min, and the equilibrium time is 0.01-0.1 min; the transfer tube temperature is 80-180°C; the PTR photochemical ionization source-time of flight mass spectrometer conditions are proton transfer reaction photochemical ionization source, vacuum ultraviolet lamp voltage is 1000-2000 V, high-purity helium water bubbling flow rate is 50-200 mL / min, and the ionization zone pressure is 2.0×10 2 ~5.00×10 2 Pa, ion source temperature 150 ~ 180 ° C, MCP voltage 3700 ~ 4800 V, detection area pressure 7.00 × 10 -6 ~3.00×10-4 Pa;

[0009] Qualitative analysis of butyric acid and its isomers: The characteristic peaks and mass numbers of each component in the detected liquor sample are compared with those of the standard to determine the butyric acid and its isomers in the liquor sample.

[0010] The isomers of butyric acid include but are not limited to isobutyric acid, acetic acid, isopentanol, ethyl acetate, 3-hydroxy-2-butanone, acetaldehyde, and the like.

[0011] The fast PTR photochemical ionization source-time of flight mass spectrometer used includes a headspace injection device, photoelectron induced H3O + Reagent ion chemical ionization source, ion transport system, and time-of-flight mass analyzer.

[0012] Compared with the prior art, the advantages of the present invention application are: the detection method provided by the present invention application does not require any pretreatment process and a large amount of organic solvents for the sample. A certain amount of liquor sample is directly taken and added to the injection bottle, and specific rapid gas chromatography-mass spectrometry conditions are selected to use rapid gas chromatography-PTR photochemical ionization source-time of flight mass spectrometry to detect butyric acid and its isomers in liquor. The method established by the present invention can quickly detect butyric acid and its isomers in liquor within five minutes, providing a powerful means for adjusting the acidity and taste of liquor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 . Tracking diagram of ion current changes of butyric acid and its isomers. DETAILED DESCRIPTION

[0014] Example 1

[0015] The test was conducted by fast gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer. The fast gas chromatography used a fast program temperature rise mode. The temperature rise program of the polar chromatographic column DB-WAX chromatographic column (30m×0.53mm×0.1μm) was 100℃ initially, maintained for 1min, then increased to 200℃ at 10℃ / min, maintained for 2min. The injection port temperature was 150-240℃, the carrier gas was high-purity helium (He), the flow rate was 3mL / min, and the split ratio was 10:1.

[0016] The conditions of PTR photochemical ionization source-time of flight mass spectrometer were proton transfer reaction photochemical ionization source, vacuum ultraviolet lamp voltage of 1400 V, high-purity helium water bubbling flow rate of 50 mL / min, and ionization zone pressure of 3.00×10 2 Pa, ion source temperature 160 °C, MCP voltage 4300 V, detection zone pressure 7.00 × 10 -5 Pa;

[0017] Directly take 1 ml of the liquor sample to be tested and place it in the injection bottle of the fast gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer. After the injection, the butyric acid and its isomers in the liquor sample to be tested are detected by the fast gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer. The corresponding characteristic peaks in the ion flow change tracking diagram of butyric acid and its isomers in the liquor are as follows: Figure 1 As shown, 1 # For butyric acid, 2 # isobutyric acid, 3# is acetic acid, 4# is # 3-Hydroxy-2-butanone, 5 # isopentanol, 6 # For ethyl acetate, 7 # It is acetaldehyde; the mass numbers of butyric acid and its isomers in white wine are shown in Table 1. According to the qualitative analysis of standard products, the corresponding components are butyric acid, isobutyric acid, acetic acid, isopentanol, ethyl acetate, 3-hydroxy-2-butanone, and acetaldehyde.

[0018] Table 1 The mass numbers corresponding to butyric acid and its isomers tested by fast gas chromatography-PTR photoionization time-of-flight mass spectrometry

[0019] Serial number Component name Characteristic peak Mass number 1 Butyric acid <![CDATA[( 13 C-C3H8O2)H + ]]> 90.064 2 Isobutyric acid <![CDATA[( 13 C-C3H8O2)H + ]]> 90.064 3 Acetic acid <![CDATA[(C2H4O2)NO + ]]> 90.019 4 3-Hydroxy-2-butanone <![CDATA[( 13 C-C3H8O2)H + ]]> 90.064 5 Isoamyl alcohol <![CDATA[( 13 C-C4H 12 O)H + ]]> 90.100 6 Ethyl acetate <![CDATA[( 13 C-C3H8O2)H + ]]> 90.064 7 Acetaldehyde <![CDATA[( 13 C-CH4O·C2H4O)H + ]]> 90.064

Claims

1. A rapid detection method for butyric acid and its isomers in liquor, characterized in that: Directly take 0.5-3 ml of liquor sample and add it into the injection bottle of fast gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer, select appropriate detection conditions, and use fast gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer to complete the detection of butyric acid and its isomers in liquor; the specific detection method is as follows: (1) Detection condition setting: fast gas chromatography-PTR photochemical ionization source-time of flight mass spectrometer was used for testing. The fast gas chromatography adopted the fast program temperature rising mode. The polar chromatographic column was DB-WAX chromatographic column. The temperature rising program was the initial temperature of 100-140°C, maintained for 0.5-2.5 min, and then increased to 140-200°C at 10-30°C / min, and maintained for 0.2-5.0 min. The conditions of PTR photochemical ionization source-time of flight mass spectrometer are proton transfer reaction photochemical ionization source, vacuum ultraviolet lamp voltage is 1000-2000V, high purity helium water bubbling flow rate is 50-200mL / min, and ionization zone pressure is 2.0×10 2 ~5.00×10 2 Pa, ion source temperature 150 ~ 180 ° C, MCP voltage 3700 ~ 4800 V, detection area pressure 7.00 × 10 -6 ~3.00×10 -4 Pa; (2) Qualitative analysis of butyric acid and its isomers: The characteristic peaks and mass numbers of each component in the liquor sample detected were compared with those of the standard sample to determine the butyric acid and its isomers in the liquor sample.

2. The rapid detection method of butyric acid and its isomers in liquor according to claim 1, characterized in that: Isomers of butyric acid include, but are not limited to, isobutyric acid, ethyl acetate, 3-hydroxy-2-butanone, acetaldehyde, and the like.

3. The rapid detection method of butyric acid and its isomers in liquor according to claim 1, characterized in that: In step (1), the rapid gas chromatography injection port temperature is 150-240° C., the carrier gas is high-purity helium (He), the flow rate is 0.8-5 mL / min, and the split ratio is 10:

1.

4. The rapid detection method of butyric acid and its isomers in liquor according to claim 1, characterized in that: The fast PTR photochemical ionization source-time of flight mass spectrometer used includes a headspace injection device, photoelectron induced H3O + Reagent ion chemical ionization source, ion transport system, and time-of-flight mass analyzer.

Images