吸取本标准溶液50mL,放入400毫升烧杯中,加入180-200毫升水及1-2滴0.2%甲基红指示溶液.滴加氢氧化铵至溶液呈黄色,再加入10毫升盐酸.将溶液加热至沸,再搅拌下加15毫升10%氯化钡溶液,继续加热煮沸3-5分钟,然后放在热处静置4小时.用慢速滤纸过滤,并以热水洗涤至氯根反应小时为止.将沉淀物及滤纸一并移入已灼烧恒重的坩埚内,灰化后再800度的高温炉内灼烧30分钟.取出坩埚,置于干燥器中冷却至室温称量．如此反复灼烧,直至恒重

Transfer 50 mL of the standard preparation to a 400 mL flask, add 180～200 mL water and 1～2 drops of 0.2% methyl red indicator solution; add dropwise ammonium hydroxide solution till yellow is evolved; add again 10 mL of hydrochloric acid and digest to boiling; stir while adding 15 mL of 10% barium chloride solution; keep digesting for 3～5 mins and then allow to stand in hot place for 4 hours; filter with low rate filter paper and rinse with hot water till the reaction subsides; transfer the precipitation as well as filter paper into a crucible which has been ignited to constant weight; when the mixture is incinerated, keep igniting it in a high-temperature furnace (800℃) for 30 mins; transfer the crucible into a desiccator and allow to cool; repeat ignition to contant weight.