异烟酸-吡唑啉酮比色法测定海水氰化物实验条件的选择

Selection of the experimental condition for detection of the volatile cyanide in seawater by isonicotinic acid-pyrazolone colorimetric method

对异烟酸-吡唑啉酮比色法中氰化物水样保存时间、氯胺T含量、水浴时间和水浴温度进行显色反应条件选择。结果表明:(1)浓度范围为0.5~5μg/L的氰化物密封水样在pH为12左右的有效保存时间达24 h,在(24~30)h内的氰化物损失率与其氰化物含量呈明显的二次方程拟合关系;(2)在氰化物含量低于4μg下,氯胺T最佳量为2 mg,且氯胺T增量(即超过最佳量的量)与吸光值降低值呈明显的正相关线性关系;(3)含量低于4μg的氰化物水样中显色稳定的水浴时间均在20 min之内;(4)含量低于4μg的氰化物水样中显色灵敏度最高时的水浴温度均在40℃左右。

Experiment conditions for the isonicotinic acid-pyrazolone colorimetric method including the preservation time of water samples, chloramine T content, water bath time and the bath temperature were studied in this paper for optimal chromogenic reaction for the detection of the volatile cyanide in seawater. The results show that the sealed water samples with the cyanide concentration from 0.5 pg/L to 5 Ixg/L could be preserved up to 24 h at pH of 12. During the time course of 24 h to 30 h, the loss rate of volatile cyanide is inversely proportional to its concentration fitted with the quadratic equation. The optimum content of the chloramine T is 2 mg when the cyanide concentrations is less than 4 μg in water sample, and there is a positive linear correlation between the absorbanee decrement and the increment of the chloramine T content beyond the optimum content. When the cyanide concentration is lower than 4 μg in water samples,the water bath time for full chromogenic reaction is within 20 minutes and the bath temperature is around 40%.