问题：铵根离子测定中出现的奇怪问题
类型：交流
提问：jackchen
等级：▲
版块：无机化学(mitang,lmybenny,wanghong,llscmary,abingchem,)
信誉：100%
回复：1
阅读：303
时间：2012-06-06 21:35:28 编辑加入/取消收藏订制/取消短消息举报该贴

我用以下方法测定铵根离子浓度，为什么吸光值随着铵根离子浓度的增加而减小（也就是反应之
后随着铵根离子浓度的增加，反应产生的蓝色逐渐变浅）？不是正比关系而是反比关系。感觉很
简单的实验不知道怎么回事。

Chemical needed
Phenol
Sodium nitroprusside (sodium pentacyanonitrosylferrate III)
Sodium hydroxide
Sodium hypochlorite (5% available chlorine)
Ammonium sulfate
2M KCl

Reagent A: 5 g phenol and 25 mg sodium nitroprusside in 500 ml water
Reagent B: 2.5 g sodium hydroxide and 0.2 ml 5% chlorine in 500 ml
water
Ammonia standards: Using ammonium sulfate, prepare a stock standard
containing 6.0 g ammonia/100 ml (will be more than 0.3 g as need to
adjust for sulfate).

Analytical Procedure
Take 4, 8, 12, 16 or 20 microliter of stock standard ammonia standard
and add to 5.0 ml of reagent A in screw cap test tube.
Close tube and votex for 10 sec.
Immediately add 5.0 ml of reagent B and close tube.
Place test tubes at 37C for 20 min.
Read absorbance immediately at 625 nm.

Prepare a reagent blank containing 5.0 ml reagent A and 5.0 ml of
reagent B. Hold for 20 min at 37C before zeroing instrument.

谢谢！！！

回复人：jackchen,▲ () 时间：2012-06-06 22:56:39 编辑	1楼
大家帮忙啊！急死了！

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