【摘要】 在聚乙烯醇存在的pH76～78的水溶液中,维生素B1(VB1)与溴百里酚蓝(BTB)反应,形成离子缔合物,此时溶液由墨绿色变为黄绿色.离子缔合物的最大吸收波长位于440nm,另在618nm有一更大的波谷,两者均可用于VB1的光度测定.当于440nm处测定时,表观摩尔吸光系数ε440=567×104L·mol-1·cm-1;当用褪色法于618nm处测量时,ε618=145×105L·mol-1·cm-1;如用440nm和618nm吸光度叠加时,ε440+618=202×105L·mol-1·cm-1.离子缔合物的组成比为VB1∶BTB=1∶1.据此提出了一种测定VB1的新的高灵敏水相分光光度法.方法简便快速并有较好的选择性.用于合成试样和维生素B1片剂的分析,结果满意.更多还原

【Abstract】 Bromothymol blue (BTB) reacts with vitamin B 1(V B 1)to form a associate in aqueous solution in the presence of polyvinyl alcohol(PVA),while colour is changed from deep green to green yellow.The maximum absorption wavelength is at 440 nm,and the wave valley of the absorption band is 618 nm.The apparent molar absorptivity of 440 nm( ε 440nm )is 5 67×10 4 L·mol -1 ·cm -1 ,and that of 618 nm( ε 618nm )is 1 45×10 5 L·mol -1 ·cm -1 .If the absorption at 440 nm and 618 nm is overlapped, ε 440+618 is up to 2 02×10 5 L·mol -1 ·cm -1 .The ratio of the ion associate is 1∶1(V B 1∶BTB)as established by Jobs method and quilibrium shift method.The method has good selectivity,most of the coexistent vitamins do not interfere the determination of V B 1.The method was used to determin V B 1 in artifical samples and vitamin B 1 tablets with satisfactory results.更多还原