分散液液微萃取-数码比色法测定环境及生物样品中亚硝酸根

Determination of Nitrite in Environmental and Biological Samples by Dispersive Liquid-Liquid Microextraction Coupled with Digital Colorimetry

研究了分散液液微萃取(DLLME)-数码比色(DC)法测定水样中的亚硝酸根。在酸性介质中,亚硝酸根和对硝基苯胺及二苯胺作用,生成红色偶氮化合物。用乙醇作分散剂,以四氯化碳为萃取剂进行分散液液微萃取,萃取液点样在薄层硅胶板上用数码相机进行数码成像。成像斑点的灰度值和亚硝酸根的浓度成正比,据此建立了测定水样中痕量亚硝酸根的新方法。对影响萃取富集效率和数码成像效果的因素进行了优化。亚硝酸根浓度在2.0～80μg/L范围内有良好的线性关系(r=0.9997);检出限为0.22μg/L。方法已应用于实际水样及人体体液分析,加标回收率在97.6%～103.4%之间,相对标准偏差在1.7%～3.4%之间;方法具有仪器成本低、方便快速、灵敏度高、环境友好等特点,可满足野外现场的检测要求。

Determination of trace nitrite in water samples with dispersive liquid-liquid microextraction （DLLME）-digital colorimetry（DC） was investigated. In acidic medium, the interaction of nitrite with p-nitroaniline and diphenylamine result in red azo compound. In the DLLME, ethanol and carbon tetrachloride were selected as dispersive solvent and extraction. Extract liquid was spotted into the silica gel TLC plate and then directly imaged by a digital camera. The spots＇ gray scale integral value was proportional to the concentration of nitrite. Thus a novel assay of trace nitrite based on DLLME-DC has been developed. Some important parameters that influence the extraction efficiency and the digital imaging result were studied and optimized. Agood linear relationship was obtained in the range of 2.0 - 80 μg/L of the nitrite with the correlation coefficients of 0. 9997 and the detection limits of 0.22 μg/L . This method has been applied for the determination of nitrite in real water samples and human body fluid with satisfactory results. The recoveries fell in the range from 97.6% to 103.4% and the relative standard deviations were between 1.7% and 3.4%. The method was proven to be low cost, simple, rapid, high sensitivity and environment friendly. It can meet the requirements for field detection.