Method: microwave heating method
Reagents and main instruments
1, microwave oven;
2. 724 spectrophotometer;
3, ferrous tartaric acid solution: Weigh 1000g of ferrous sulfate and 5000g of sodium potassium tartrate, dissolved in water and dilute to 1L, pH = 7.5;
4. Phosphate buffer solution.
Phosphate buffer solution configuration
1 Take 850ml of 1/15 mol/L potassium dihydrogen phosphate solution and 150ml of 1/15 mol/L potassium dihydrogen phosphate solution; Shanghai Chuangsai Technology provides potassium dihydrogen phosphate, 7778-77-0, CP; No.: C16-P10318-500g, the price is 47 yuan.
2 Weigh 0.3g of ground tea leaves (accurate to 0.0001g) in a 100ml volumetric flask;
3 add 40ml of distilled water, seal the bottle mouth with a sealed bag, and fasten the rubber band;
4 placed in the microwave oven, microwave heating in the mid-range power for 5min, the end of the turntable, remove the sealed bag, filter into a 50ml volumetric flask, to a constant volume;
5 Accurately absorb 1.00ml of the above test solution, inject into a 25ml volumetric flask, add 4ml of water and 5ml of ferrous tartrate solution; Shanghai Chuangsai Technology provides potassium hydrogen tartrate, 868-14-4, ACS; commodity number: C16-P10112-500g The price is 195 yuan.
6 thoroughly mix and add buffer with pH=7.5 to the scale;
7 The absorbance was measured using a 10 mm cuvette at a wavelength of 540 nm with a reagent blank solution as a reference. Shanghai Chuangsai Technology provides a one-time standard cuvette, 4.5ml; commodity number: C81-CUV010045, 1000 pcs/carton, price 740 yuan.
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