A Highly Portable Smartphone-Based Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection

Work has rarely been reported on a highly portable smartphone-based capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C⁴D). Herein, a highly portable phone-based CE (130 mm × 190 × 70 mm, 1.4 kg) with C⁴D and Bluetooth communication, as well as user-interface software, was developed for portable analysis. To demonstrate the device, six metal ions were selected as model analytes for verification and successfully applied to the detection of ions in tap water. The analytical performance highlighted that the runs and data analysis of the CE-C⁴D device could be controlled via the user interface based on smartphones. Furthermore, the experiments showed that (i) the linear ranges of six metal ions were between 6 and 1500 μmol/L with a correlation coefficient of more than 0.9934; (ii) the limit of detection (LOD) values were within 1.84-4.33 μmol/L; (iii) the intra-day deviations of migration time and peak area were 2.40-5.24% and 0.75-2.82% (<i>n</i> = 5), respectively. Although the LOD is not the most optimal among current portable devices, the results still indicated the satisfactory analytical performance and potential of the developed device, software, and method for portable separation and quantitation of analytes from various fields.