Determination of soy isoflavones in health foods by ultraviolet spectrophotometry - Master's thesis - Dissertation

Key words: ultraviolet spectrophotometry; health food; soy isoflavones; analysis instrument ; purpose: using soybean aglycone as standard, UV spectrophotometric detection of soy isoflavones in three commercially available health products Total concentration. Method: The health care product was ultrasonically extracted with methanol water (80 20, V/V) at 70 °C for 40 min, and the active ingredient daidzein in soybean was used as the standard. The detection wavelength was 254 nm, and the sample content was calculated. Results: Regression equation Y=0.138X-0.0056, R2=0.9994, linear range: 0.8～6.4mg/L, average recovery rate is 99.32%, RSD=0.044%. Conclusion: This method is suitable for detecting soybean isoflavone content in health food. Soy There are many methods for the determination of isoflavone content, mainly high performance liquid chromatography (HPLC), high performance liquid chromatography mass spectrometry (HPLCMS), gas chromatography (GC) and capillary electrophoresis. We use ultraviolet spectrophotometry and other methods Compared with the simple and fast, and the equipment requirements are not high, the current method for determining the content of soy isoflavones in health foods is rarely reported. 1 Materials and methods 1.1 Materials UV-1800APC UV-visible spectrophotometer; RE5 2A rotary evaporator, KQ10 ultrasonic machine. Daidzein standard (China National Institute for the Control of Pharmaceutical and Biological Products 1502200101). 3 kinds of commercially available health products: An Sleeping Beauty; Tianshen; Xinyi. Methanol (analytical pure). (Analytical 1.2 Method 1.2.1 Extraction and separation of soybean isoflavones in health products Take 4 health supplements, accurately weighed in quality, placed in a 100mL round bottom flask, add 800mL / L methanol 70mL ultrasonic extraction for 40min, hot suction filtration, methanol extraction The liquid was distilled off under reduced pressure at 35 ° C, then water was distilled off under reduced pressure at 45 ° C, and then 20 mL of methanol was added to dissolve as a test solution. 1.2.2 Test of soybean isoflavone aglycone 1.2.2.1 Silica gel for thin layer chromatography GF254 thin layer plate, using anhydrous methanol (10:0.5) as developing agent, sampled with standard sample and sample (dissolved in anhydrous methanol), detected under 254nm UV lamp, see Figure 1. 1.2.2.2 UV spectrophotometric detection UV-1800APC UV-visible spectrophotometer was used to detect anhydrous methanol, standard and sample in the range of 200-400nm (Fig. 2~6). 2 Results 2.1 Preparation of standard solution and preparation of standard curve accurately weigh soybean Aglycone standard 2.0mg, placed in 25mL capacity In the bottle, dissolve in methanol and dilute to the engraved line, shake well. Accurately absorb the standard solution 0.1, 0.2, 0.3, 0.4, 0.6, 0.8mL, place in a 10mL volumetric flask, dilute with methanol to the engraved line, shake Even with methanol as the blank, measure the A value at the wavelength of 254nm. Take the concentration as the abscissa and the A value as the ordinate to draw the standard curve. The regression equation Y=0.138X-0.0056, R2=0.9994, linear range 0.8～6.4 Mg/L. 2.2 Determination of content accurately Take 0.01 mL of the test solution, dilute 1000 times to 10 mL with absolute methanol, and measure the A value 3 times with UV-1700PC UV spectrophotometer at 254 nm. Value. Determination results, according to the standard curve to calculate the sample content (Table 1). Table 1 three samples of content (omitted) 2.3 precision test the same test solution (day female) 0.01mL, diluted 1000 times with anhydrous methanol to 10mL constant volume, using TU9100 UV spectrophotometer to measure 6 times A value at 254nm, respectively, 0.102, 0.099, 0.100, 0.100, 0.099, 0.096, the result RSD = 0.133%, indicating that the instrument precision is better. 2.4 The sample recovery rate experiment [3] adds different amounts to the known content sample (day female) The daidzein standard was determined according to the method of 2.2, and the recovery rate was calculated. The results are shown in Table 2. The average recovery rate was 99.32%, RSD=0.044%, indicating that the recovery rate of the method was better. Table 2 recovery rate determination Results 3 Discussion Because the configured test article uses methanol as the solvent, soy isoflavones may be decomposed during the placement process, so the stability test was carried out. The same test solution (day female) was measured once every 30 minutes. The results of 6 measurements were 0.102, 0.099, 0.097, 0.095, 0.096, 0.092, and RSD=0.25%, indicating that the test solution was stable within 3 hours. 4 Conclusion UV spectrophotometric determination of soy isoflavone content in health food and other methods It is relatively simple and fast, requires less equipment and equipment, and has good reproducibility. It is suitable for the determination of soy isoflavones in health foods. Key words: ultraviolet spectrophotometry; health food; soy isoflavones; analysis instrument Com;