应用斐林试剂与碘液时的几点注意问题

实验原理：淀粉和蔗糖为非还原性糖，它们在酶的作用下，都能水解成还原性糖，还原性糖能与斐林试剂发生氧化还原反应，生成砖红色的氧化亚铜沉淀。     

例谈原子综合题

例1 已知放射性同位素^14C的半衰期是5730年，现测得某生物化石中^14C只剩下正常量的1／32，说明该生物死后至今经历了大约多少年     

辐射环境管理监测档案工作初探

近年来，随着我省经济的高速发展，核技术和放射性同位素应用于相关产业进入快速发展期，涉及到国民经济的许多部门和人民的日常生活，给人们的工作和生活带来了前所未有的便捷。但是，辐射技术在带给人类巨大利益的同时，也给环境安全和社会带来潜在危险。如果处理不当，甚至会危及人类身体健康和生命安全。     

分光光度法测定海带中的碘

讨论了用Fe^2＋-邻二氮菲体系分光光度法间接测定海带中微量碘含量的方法。本实验以NH4Fe（SO4）2作为氧化剂，使用邻二氮菲作为显色剂，通过测得吸光度与Fe^2＋溶液浓度成线性关系，可间接测定海带提取溶液中I^-的浓度。该法具有准确度高，重现性好，简便快速的特点，是测定海带中微量碘的一种较理想的方法。     

如何避免碘遇淀粉变蓝后又褪色

在用碘检验淀粉的实验中,常出现碘使淀粉变蓝后,过一段时间又褪色的情况。主要是碘与淀粉形成的络合物不稳定易分解,所以褪色。实验时,在碘液中加少量的盐酸或变蓝后加少量的盐酸,就会避免褪色。     

生物学中的放射性同位素类题目例析

历年高考试题涉及放射性同位素的题目已广泛出现．此类题目涉及内容较广，难度不大，但必须在牢固掌握基础知识的程度上才能将此类题目做好．下面是笔者结合多年指导高三复习的体会，对此类题目进行内容上的分类例析，谨供广大师生参阅．     

Investigation of iodine concentration in salt,water and soil along the coast of Zhejiang,China

Objective: We aim to describe the environment iodine concentration in salt, water and soil along Zhejiang Province coast in the China foreland. It will be helpful for us to judge whether this area is insufficient in iodine and universal iodized salt is necessary or not. Methods: We collected iodized salt samples, drinking water samples (tap water in the towns, and well water or spring water in the villages), water samples from different sources (ditches, lakes, rivers) and soil samples through random sampling in June, 2005. Salt, water and soil iodine was detected by arsenic-cerium redox method. Statistical analysis was expressed as mean±SEMby Windows SPSS 13.0. Results: (1) The iodine concentration in salt was 27.9±4.33 mg/kg (n=108). (2) Seventy-five water samples were collected. The water iodine value was 0.6～84.8 μg/L (mean of 11.66 μg/L). The watershed along the Qiantang River has significantly higher iodine content than the water in Lin'an in mountain area (P＜0.01). The iodine content and mean iodine content of tap water, well or spring water and natural water sources were 4.30±2.43 μg/L (n=34), 23.59±27.74 μg/L (n=19)and 12.72±10.72 μg/L (n=22) respectively. This indicated that among environmental water sources, the ditch iodine content was the highest with river water iodine being the lowest (P＜0.01). (3) Soil iodine value was 0.11～2.93 mg/kg (mean of 1.32 mg/kg).Though there was no statistical difference of soil iodine in different districts (P=0.131), soil iodine content correlated positively with water iodine content. Conclusion: Iodine concentration in salt accords with national policy of adding iodine in salt. Foreland has more iodine in water than mountain area. The data reflected that water and soil iodine in foreland area was not high, which suggests universal iodized salt should be necessary. Environment iodine has relatively close association with pollution.     

碘酸钙溶度积的测定

采用碘量法测定碘酸钙溶度积常数，方法十分简单，测定结果满意．