流动注射-Folin-Denis法测定制革废水中单宁

在pH 12.4的硼砂-氢氧化钠缓冲溶液中，单宁能还原Folin-Denis(佛林-顿尼斯)试剂生成蓝色化合物，此蓝色化合物在760 nm处有最大吸收，据此建立了一种快速的流动注射分光光度法测定制革废水中单宁的方法。讨论了试剂流速、进样体积、Folin-Denis试剂用量、溶液pH值、缓冲溶液用量和反应圈的长度对测定的影响，确定了最佳实验条件。结果表明，单宁浓度分别在0.2~10 mg/L和10~50 mg/L范围内符合比尔定律，方法检出限为16.84 μg/L（三倍基线噪音）。对含量为500 μg/L和20 mg/L的单宁标准溶液分别进行14次平行测定，其相对标准偏差分别为3.2%和2.1%。制革废水中常见的离子对测定没有干扰（SO₃^2-除外，可以通过加热预处理去除），可用于现场在线分析。本方法已用于制革废水样品中单宁的测定，测定结果和标准方法GB/T 15686-2008测得值吻合，相对标准偏差（RSD，n=8）小于 4%。

Determination of tannins in tannery wastewater by flow injection-Folin-Deni

In sodium tetraborate-sodium hydroxide buffer solution at pH 12.4,tannins could reduce Folin-Denis reagent to form blue compound with the maximum absorption wavelength at 760 nm.Based on this,a rapid flow injection spectrophotometric method was proposed for determination of tannins in tannery wastewaters.A discussion was conducted on the impact of reagent flow rate,injection volume,amounts of Folin-Denis reagent,pH of the solution,dosage of buffer solution and the length of reaction coil on the determination and the optimal experimental conditions had been obtained.The results showed that Beers’ law was obeyed in the concentration range of 0.2-10 mg/L and 10-50 mg/L for tannins respectively,and the detection limit of the proposed method from three times of baseline noise was 16.84 μg/L.The relative standard deviation was 3.2% and 2.1% for fourteen parallel determinations of 500 μg/L and 20 mg/L tannins standard solution,respectively.Commonly co-existing ions except SO32-(which could eliminated by heating pretreatment) in tannery wastewaters had no interference with determination of tannins,so it could be applied for the on-site online analysis.The proposed method had been applied to the determination of tannins in tannery wastewaters.The results were consistent with those obtained by standard method GB/T 15686-2008 and the relative standard deviations(RSDs,n=8)were less than 4%.