1.试液的制备:用手称准确称样品0.2克放入试管中,加入含硒硫酸2毫升,再加无水硫酸钠固体0.1克(如黄豆粒大即可)。试管口加一小漏斗,倾斜地放在铁筐内,于火上加热煑,先以小火,继以中火一直将样品煑到变成白色后,再继续煑十分钟。经冷却后,用蒸馏水将溶液全部洗到有100毫升刻度的并中,加蒸馏水到刻度,使溶液一毫升中含样品0.002克,用此液作为分析试液。 1. Preparation of the test solution: Accurately weigh 0.2g of the sample by hand into a test tube, add 2ml of selenium-containing sulfuric acid, and add 0.1g of anhydrous sodium sulfate solid (for example, soybean particles can be large). Test tube mouth plus a small funnel, tilt placed in the iron basket, the heat on the fire 煑, first with a small fire, followed by the fire has been the sample 煑 until it becomes white, and then continue 煑 ten minutes. After cooling, the solution was washed with distilled water to 100 ml graduated and added distilled water to the mark so that the solution containing a sample of 0.002 g in 1 ml, using this solution as the assay solution.