分光光度法测定化肥中有害成份硫氰酸盐

当SCN 浓度 >5mg/L时对植物尤其是农作物就会产生危害 ,因此 ,控制化肥中SCN- 限量十分必要。测定SCN- 的电位滴定法2 ] 灵敏度高 ,线性范围宽 ,但样品中Cl- /SCN- >1比例 ,会严重干扰测定 ,必须分离。离子色谱、高效液相色谱大多是针对痕量SCN- ( <1mg/L)测定 ,很有效。化学滴定法要求SCN- > 1 % ,且Cl- 干扰也同样需加以考虑。对于SCN- <0 1mg/L ,甚至 μg/L级的测定 ,更多地用动力学光度法3] ,但分析样品一定要基体少 (如水样 )。且该法对温度、放置时间要求极严格。本文利用Cu2 +、吡啶 (Py)、SCN- 在氯仿中形成稳定的…

A Study of colorimetric analysis for thiocyanate in fertilizers

A Study was made for the purpose of improving method of determining thiocyanate in ferilizers.The report shows the two color systems of both Cu-Py-SCN/CHCl_3 complex in organic phase and Fe-SCN complex in re-extract water phase may be used to determine thiocyanate 0.005% above in fertilizers.The precision and accuracy of the methods are all satisfactory within attainable range.The concentration ranges of SCN~- for Berr's law are respectively following as:(A)1-20 mg/L(organic phase),(B)0.1-8 mg/L(water phase).After a lot of sample treatment experiments and recovery of SCN~- tests,it recommended that the true amount of SCN~- in fertilizers could be determined in alkaline solution medium.