mixcarefully, 30 min waterbath cooling.Slowly along tubewall l0mL ethanol solution potassiumhydroxide, which makes two liquid layers, stuffed, shaking violently mixed placed10min. 1cm Cuvette, reagent blank zero, 440nmwavelength absorbance measurement. calculationsaAcid,shake carefully 5min, began shakewhen deflated. Static hierarchy, discard sulfate layer, add 50 mL sulfuricacid repeat treatment once. benzenelayer anotherseparatory funnel, washed three times anhydroussodium sulfate, collected glassdistillation apparatus distillation distillation liquid. Dinitrophenylhydrazine solution: weigh 50mg 2-4 one twoNitrophenylhydrazine, l000mL solution benzene.Trichloroacetic acid solution: weigh solidthree acid plus100mL benzene dissolved. Ethanol solutions potassiumhydroxide: weigh potassiumhydroxide, refiningethanol 100 mL dissolve, cold dark night-get upper clear fluid. Solution Brown should preparedagain. instrumentsspectrophotometer. Precision weighing about 0.025g~0 analysissteps. Plac