1 Scope This method uses packed column gas chromatography to determine the alcohol, ester, and aldehyde content in liquor, including n-propanol, isobutanol, sec-butanol, n-butanol, and isoamyl alcohol, which are esters. Ethyl acetate, ethyl butyrate, ethyl valerate, ethyl hexanoate, ethyl lactate, acetaldehyde and isovaleraldehyde belonging to aldehydes, and acetal, the result is expressed as mg / 100mL Decimal.
2 The principle uses a packed column DNP dedicated to the analysis of the main flavor components of liquor. The mixing column has different partition coefficients in the gas-liquid two-phase according to the liquor flavor components. When flowing through the DNP mixing column, the gas-liquid two-phase action has successively changed from After flowing out of the chromatographic column, ionization was detected in a hydrogen flame to obtain the corresponding tailing peak. The former is rare. > Chromatographic peak signal, quantified by the standard sample retention time qualitative internal standard method.
3 Reagent
3.1 Chromosorb W (AW-DMCS) 60/80 mesh or 80/100 mesh
3.2 Dinonyl Phthalate Abbreviated as DNP
3.6 The standard solution of alcohol, ester and aldehyde is chromatographically pure reagents n-propanol, isobutanol, sec-butanol, n-butanol, isoamyl alcohol, ethyl acetate, ethyl butyrate, valeric acid, ethylhexanoic acid, ethyl Twelve kinds of standard samples such as ester, ethyl lactate, isovaleraldehyde, acetal and so on were prepared with 60% ethanol solution to make up a standard sample solution with a volume ratio of 2%. The exact concentration depends on the specific gravity of each standard sample reagent.
3.7 Internal standard solution of n-butyl acetate 17.6g / L
With the analytical reagent n-butyl acetate content not less than 99.0%, the internal standard solution with 60% ethanol solution to make up the volume ratio of 2% is 17.6g / L.
4 Instruments
4.1 The gas chromatograph is equipped with a hydrogen flame ionization detector
4.2 Microsampler 10mL
5 Operation steps
5.1 Preparation of chromatographic column Weigh 15.0g of support, (Chromosorb W) also call 3.00g DNP accurate to 1mg, its amount is equivalent to 20% of the weight of the support and 1.05g Tween-80 accurate to 1mg its amount is equivalent to the weight of the support 7%, in another small beaker, weigh the same volume of anhydrous methanol as the support, first dissolve DNP and Tween-80 in a small amount of methanol and transfer to an evaporating dish, then pour the remaining solvent into the stirrer, Then slowly pour the support into the mixture while stirring, place the evaporating dish on a 50 water bath and turn it from time to time to evaporate the solvent. When it evaporates to dryness, move it to an oven at 90-95 ° C for 1 hour. Take it out and cool to room temperature. This packing was packed into a chromatographic column with an inner diameter of 2mm × 2m and was washed with a carrier gas and aged at 115 ° C for 16h.
5.2 Chromatographic conditions According to the instrument manual, adjust the flow rate of carrier gas hydrogen, etc., the chromatographic conditions and the best choice through the test, operating conditions so that the chromatographic peaks of the components to be measured can be better separated from each other, for Accurate measurement results. The chromatographic peaks of the internal standard of n-butyl acetate and isoamyl alcohol must be completely separated. The column temperature of the column is analyzed by a programmed temperature rise. The initial column temperature is 65 ℃ and the temperature is constant for 5 minutes. Ethyl acetate chromatographic peaks can be eluted by isothermal column temperature 100 ℃. At this time, isovaleraldehyde and sec-butanol cannot be separated, and the temperature of the inlet and detector is set to 150 ℃.
5.3 Determination of component qualitative and correction factor f value:
Accurately draw 0.50mL of the component standard solution with a volume percentage of 2%, mix and transfer to a 10mL volumetric flask, dilute with 60% ethanol to the mark and add 0.20mL n-butyl acetate internal standard solution (17.6g / L), wait for the chromatograph After the baseline is stable, inject 1.0mL with a micro sample injector, and record the retention time of the component chromatographic peak and the peak area retention time. It is used to characterize the chromatographic peaks in the sample and determine the component peak area and internal standard The ratio of peak areas is used to calculate the relative mass correction factor f of each component.
5.4 Determination of sample Pour wine sample to the mark in a 10mL volumetric flask, accurately add 0.20mL of internal standard solution 17.6g / L, mix well, inject under the same conditions as the f-value determination, and determine the peak of each component according to the retention time And record the peak area of ​​each component peak and the area of ​​the internal standard peak to calculate the content of the corresponding component in the wine sample.
6 Calculation of the results

In the formula:
X --- the content of corresponding components in the wine sample mg / 100mL
f --- component relative mass correction factor
A --- Peak area of ​​the internal standard when measuring the internal 1 f value
A1 — Peak area of ​​alcohol ester aldehyde when f value is measured
A --- Inside 2-Peak area of ​​the internal standard when measuring wine samples
A2-Peak area of ​​alcohol esters and aldehydes in the determination of wine samples
G1 —f value determination The content of the corresponding component in the standard sample mg / 100mL
35 .-- 2—Content of internal standard mg / 100mL
* Because acetaldehyde is difficult to obtain standard pure product, its f-value cannot be measured by experiment. It can only be estimated from the literature value. When using this method, the f-value of acetaldehyde is obtained by multiplying the isoamyl alcohol f-value by a factor of 2.0.
7 Precision The difference between the two measured values ​​of the same sample shall not exceed 5% when the component is greater than 10 mg / 100mL and shall not exceed 10% when the content of the component is less than 10mg / 100mL.

This article comes from the determination of alcohol, ester and aldehyde content in liquor by gas chromatograph | Scientific Instrument Online Original Link: http: //

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