Flatbed-scanner-based colorimetric Cu2+ signaling system derived from a coumarin–benzopyrylium conjugated dye

Abstract

In this study, we developed a flatbed-scanner-based Cu2+-selective signaling method using a coumarin–benzopyrylium conjugated dye platform. The designed sensors (CB-1 and CB-2) were readily synthesized by the reaction of coumarin–benzopyrylium hydrazide with salicylaldehyde or 2-hydroxynaphthaldehyde, respectively. Sensor CB-1 exhibited pronounced colorimetric and fluorescence signaling behaviors toward Cu2+ ions in 50% aqueous acetate buffered (pH 4.7) acetonitrile solution. The Cu2+ signaling of the developed sensor was not affected by the presence of environmentally relevant metal ions. The detection limit of sensor CB-1 for Cu2+ ions was estimated to be 4.0 × 10−8 M (2.5 ppb). In addition, to develop a convenient and straightforward Cu2+ detection method for nonprofessional personnel and practical field applications, the colorimetric determination of Cu2+ ions using a flatbed scanner, a readily available IT device, was investigated. Using simulated semiconductor wastewater as a practical sample, the Cu2+ levels were readily determined by a flatbed scanner in transmittance mode with a sensitive detection limit of 2.9 × 10−7 M (18 ppb).