(1) absorption solution Weigh 4.3g of cadmium sulfate (3CdSO4 8H2O), 0.3g of sodium hydroxide and10g of poly (ammonium phosphate) and dissolve them in water respectively. When in use, the three solutions are mixed, shaken vigorously until they are completely mixed, and then diluted to 1L with water. This solution is a white suspension, which should be shaken by force every time and measured again.
(2) Measure 50 ml of sulfuric acid from the solution of p-aminodimethylaniline, slowly add it into 30 ml of water, cool, weigh 12 g of p-aminodimethylaniline hydrochloride (also known as p-amino -n, n- dimethylaniline dihydrochloride) [(CH3) 2nc6h4nh22HCl], dissolve it in the sulfuric acid solution, and keep it in the refrigerator for one year. When it is used, measure it.
(3) Weigh 100g ferric chloride (FeCl36H2O) in ferric chloride solution, dissolve it in water, and dilute it to 100ml. If there is precipitation, it should be filtered before use.
(4) When mixed chromogenic solution is used, it should be mixed according to the ratio of 1ml p-aminodimethylaniline dilute solution and 1 drop (0.04ml) ferric chloride solution. This mixed solution should be prepared now, and any precipitate should be discarded.
(5) Diammonium hydrogen phosphate solution Weigh 40g Diammonium hydrogen phosphate [(NH4) 2HPO4] and dissolve it in water and dilute it to 100ml.
(6) Potassium iodate standard solution C (1/6kio3) = 0.1000 mol/L, accurately weigh 3.5668g of potassium iodate (excellent purity) dried at 105℃ for 2 hours, dissolve it in newly boiled and cooled water, and transfer it to/kloc-.