Determination of ethanol content in alcoholic beverages

It is reported that the content of ethanol in beverages is generally low, and it is generally difficult to accurately determine it by the attached temperature pycnometer method and hydrometer method. The international and national standard methods all use distillation to separate ethanol, then use potassium dichromate to oxidize it in sulfuric acid medium, and then titrate excess potassium dichromate with ammonium ferrous sulfate in the presence of phenanthroline ferrous sulfate as indicator. This method is only suitable for fruit and vegetable juice products with ethanol content not higher than 5%, which has certain limitations and complicated method. After the sample was sucked by syringe, it passed through C 18 column and was determined by gas chromatography. However, this method is not only suitable for the determination of ethanol in fruit and vegetable juice drinks, but also suitable for the determination of ethanol in milk-containing drinks, fruit wine, yellow wine, beer and other drinks. This method is simple, rapid, accurate and reliable. The average recovery rate is 98.6% and the detection limit is 7. 7 cubic meters/liter.

1 experimental part

1. 1 instruments and reagents

Instrument: 1 1 0 2 gas chromatograph is equipped with a hydrogen flame detector (F I D) and a data processor, and C 18 is designed as a small column.

Use syringes;

Chromatographic column: special capillary column for routine analysis of large-caliber liquid and anhydrous ethanol (chromatographic purity).

1.2 sample pretreatment

Use a special syringe to directly suck the sample solution. After assembling the C 18 column, push the syringe to make the sample solution flow out after passing through the C 1 8 column to obtain a clear filtrate for C and C analysis.

1.3 chromatographic conditions

Column temperature: programmed temperature rise of 65℃(3 minutes) and l30℃(2 minutes).

Detector temperature: 200. Syringe temperature: 200.

Carrier gas: high purity nitrogen with flow rate of 4.0 rnl/min；; The hydrogen flow rate is 22.5 ml/min; Air: 160 me/ rain.

Tail blowing: 39.0l/min.