异烟酸-吡唑啉酮比色法测定咖啡因中残留氰化物

Determination of cyanide in caffeine by isonicotinic acid- pyrazolone colorimetric method

目的：采用异烟酸-吡唑啉酮比色法测定咖啡因中残留氰化物。方法在中性条件下，氰化物与氯胺T反应生成氯化氰，再与异烟酸作用，经水解后生成戊烯二醛，最后与吡唑啉酮缩合生成蓝色染料，在638 nm处的吸光度与氰化物含量成正比。结果氰化物浓度在0.00774～0.19344μg·mL^-1范围内具有良好的线性，相关系数r=0.99997，平均回收率为100.2％（RSD=0.49％，n=9）。结论该方法灵敏、准确，适用于咖啡因中氰化物的测定。

Objective Using isonicotinic acid-pyrazolone colorimetric method for the content determination of CN- in Caffeine. Methods In neutral medium,the cyanide reacted with chloramine T to form cyanogen chloride. Cyanogen chlo-ride reacted with isonicotinic acid and then hydrolyzed to form glutaconaldehyde which reacted with pyrazolone to form blue dye. The cyanide content had positive correlation with absorbance of the blue dye at 638 nm. Results The range of linear relationship of cyanide was 0. 007 74～0. 193 44 μg·mL^-1（r=0. 999 97）. The average recovery was 100. 2%（n=9）;The relative standard deviation was 0. 49%. Conclusion The method was sensitive and accurate,which was suitable for the determination of cyanide in caffeine.