喷墨打印微流体纸基数码灰度比色法快速检验氯酸钾

Determination of Potassium Chlorate with Microfluidic Paper-based Analytical Devices by Digital Colorimetric Assay

目的研究喷墨打印微流体纸基数码灰度比色法测定可疑物样品中氯酸钾的新方法。方法在浓盐酸环境下,氯酸钾与盐酸苯胺络合生成稳定的有色络合物。滤纸具有亲水性,接触记号笔墨水后使滤纸变得疏水。计算机设计好模板将图案喷墨打印到滤纸上。当溶剂挥发后,着色剂、疏水树脂留在滤纸纤维上改变滤纸原来的亲水性,形成了可视的疏水屏障。以记号笔墨水配制成疏水性的感应油墨,依托喷墨打印机,在滤纸上喷墨打印形成高重复、稳定的图案,形成稳定的点样空间。在亲水空间上首先滴加盐酸苯胺试剂,氯酸盐与其中的盐酸苯胺络合生成有色物质。氯酸盐的浓度不同得到颜色深浅不同,对其进行灰度处理读取像素点灰度值。结果纸基拍照获取数字图片该灰度值与KClO_3浓度呈正相关。当连续喷墨打印4次时,圈形的亲水空间形成;最佳的点样体积为20μL;Scion image 4.03软件处理方式效果最好。KClO_3浓度为50~90μg/mL范围时,像素点的灰度值与浓度有良好的线性关系(R^2=0.99),定性检出限为0.92μg/mL。结论本文建立的氯酸钾检验方法对环境光源无特殊要求,操作简单、成本低、高效快速,适合野外勘查现场检验。

Objective To determine potassium chlorate in suspicious object with microfluidic paper-based analytical devices by digital gray colorimetric analysis. Methods In acidic medium, potassium chlorate reacts with hydrochloric aniline to form stable colored chelate complexes. Hydrophobic barrier was built on filter paper through inkjet primer with sensing ink prepared from permanent mark ink. After contacting with sensing ink, the filter paper changed into hydrophilicity from hydrophobicity. The pattern with computer was designed, and then printed onto filter paper with sensing ink. After evaporation of ink solvent, the colorant, hydrophobic resin remaining in the filter cellulose built up a visible hydrophobic barrier. Thus the uniform and stable spotting space had been created. The hydrophobic zone was spotted with 20 μL hydrochloric aniline reagents followed by KC103 solution, each with 10 minutes of air-dry. The image of the spot photos was grayscale processed, and image analysis software was used to measure the gray values of detection zones for quantitative analysis. Some important parameters that influenced the efficiency and the digital imaging result were studied and optimized. Results The results indicated that the concentration of sample was positively correlated with the image gray value. Hydrophilic circle zone was formed after four successive inkjet printings. 20 μL of spotting volume was optimum, and Scion Image 4.03 performed better. A good liner relationship was obtained in the range of 50-90 μg/mL （Re=0.99） with detection limit of 0.92 μg/mL. Conclusions This method can perform quantitative analysis of KC103 at very low cost, and well meet the requirements of site detection due to its simplicity and rapidity.