Dehydroacetic acid (DHA) is a highly effective antiseptic and antifungal agent. It has certain antibacterial ability under acid and alkali conditions, especially for yeast, bacteria and mold. It is often used in juice and pickles. Foods such as cakes, starch products, meat products, fermented soy products, compound seasonings, etc., and food additives are preserved against mildew and mildew. However, due to its toxicity and harm to human health, the detection of its content has received increasing attention. Shandong Tengzhou Luchuang Analytical Instrument Co., Ltd. compares and optimizes various detection methods of DHA in the report, and develops a fast and accurate DHA gas chromatograph detection program to protect the quality and safety of food production and processing enterprises.
Dehydroacetic acid (DHA) is another new broad-spectrum preservative after benzoic acid, sorbic acid and p-hydroxybenzoic acid ester. It has strong antibacterial activity against mold and yeast, and is 2~10 times that of sodium benzoate. Dehydroacetic acid is found in many foods on the market in China, and there are excessive use and over-range use. China's Food Additive use standard GB 2760-2007 specifies that the maximum use of dehydroacetic acid and its sodium salt in various pickles, fermented soy products, etc. is 0.3 g / kg, in cakes, fillings such as Mid-Autumn moon cakes, etc. The maximum usage is 0.5 g/kg.
Luchuang Analytical Instruments Co., Ltd. used benzoic acid as an analytical protective agent to determine the content of dehydroacetic acid in food by capillary column-gas chromatography. The addition of a protective agent increases the sensitivity and repeatability of the method. The method is simple in operation, low in detection limit, good in repeatability, and saves organic solvent. It has a good application prospect. At the same time, the analysis of the use of protective agent also provides a reference for gas chromatograph analysis of polar substances.
Testing equipment: gas chromatograph, hydrogen flame ionization detector, chromatography workstation, gas source.
Chromatographic conditions: the column is an elastic quartz capillary column (30 m × 0.32 mm × 0.25 μm); the carrier gas is nitrogen, the flow rate is 2.5 ml / min, constant current mode; the tail gas is nitrogen, the flow rate is 40 ml / min; The detector temperature is 280 ° C, the air flow rate is 400 ml / min, the hydrogen flow rate is 40 ml / min; the inlet temperature is 230 ° C, no split injection, the shunt valve is opened after 0.75 min, the injection volume is 1 μL; Temperature ramping procedure: initial temperature 70 ° C, ramp up to 170 ° C at 10 ° C / min; post run: 270 ° C for 5 min. Quantification by external standard method.
The chromatographic conditions were determined. The mass concentration of dehydroacetic acid was linearly related to the peak area in the range of 2.5-1000 mg/L. The detection limit (3S/N) of the method was 2.0 mg/L, and the lower limit of the method was determined. 10S/N) is 0.005 g/kg.
Determination method: Weigh 10.000 g of the sample into a 50 mL plastic centrifuge tube, add 250 μL of glacial acetic acid, 10 mL of acetonitrile, mix and add 4 g of anhydrous magnesium sulfate and 1 g of sodium chloride, and shake vigorously 1~2 immediately. Min, centrifuge at 4 500 r/min for 3 min, take 2.00 mL of the upper acetonitrile solution and place it in a 10 mL centrifuge tube. Add 80 μL of 50 g/L benzoic acid solution and 300 mg of anhydrous magnesium sulfate. After vortexing for 30 s, The mixture was centrifuged at 4 000 r/min for 2 min, and the supernatant was filtered through a 0.45 μm filter, and the filtrate was taken for measurement.
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