A Rapid In Situ Colorimetric Assay for Cobalt Detection by the Naked Eye

Abstract

A simple, rapid, and convenient colorimetric chemosensor of a specific target toward the end user is still required for on-site detection and real-time monitoring applications. In this study, we developed a rapid in situ colorimetric assay for cobalt detection using the naked eye. Interestingly, a yellow to light orange visual color transition was observed within 3 s when a Chrysoidine G (CG) chemosensor was exposed to cobalt. Surprisingly, the CG chemosensor had great selectivity toward cobalt without any interference of other metal ions. Under optimized conditions, a lower detection limit of 0.1 ppm via a spectrophotometer and a visual detection limit of 2 ppm with a linear range from 0.4 to 1 ppm (R2 = 0.97) were determined. Moreover, the CG chemosensor is reversible and maintains its functionality after treatment with chelating agents. In conclusion, we show the superior capabilities of the CG chemosensor, which has the potential to provide extremely facile handling, high sensitivity, and a fast response time for applications of on-site detection to real-time cobalt monitoring for the general public.

Rotational Isomerization about C−C Single Bond in a Novel ICT Probe Facilitates Naked‐Eye, Colorimetric and Ratiometric Detection of Cobalt in Aqueous Samples**

“…Limitations of these methods have encouraged researchers to develop other conventional analytical methods. In line with the above discussion, naked‐eye sensors with observable color change [5,19,30–34] have become more common compared to other analytical tools due to their cost effectiveness, [30] simplicity, [31] quick response time, [35] high selectivity and sensitivity [35,36] …”

“…Cobalt, a d‐block transition metal, is ferromagnetic. Cobalt is used as an essential material in high technology deliverables including jet engines and gas turbines, [1] rechargeable batteries, [2–5] super alloys, [2,3,5] catalysts, [4–6] and electroplating [7] . Surplus demand for raw material and subsequent mining leads to excessive accumulation of cobalt in the environment [8] .…”

Determination of Time since Deposition of Fingerprints via Colorimetric Assays

“…In the past decade, the development and use of on-site colorimetric assays has been a rapidly expanding market. The fields in which these methodologies are used span from biomedical − to environmental , to forensics , largely due to their speed, versatility, and ease of use, many of which have potential to be paired with smart device imaging applications. For these reasons, three chemical assays that generate three distinct colorimetric readouts were chosen for this investigation.…”

Color Changes in Ag Nanoparticle Aggregates Placed in Various Environments: Their Application to Air Monitoring

“…On the other hand, optical sensors are essentially unaffected by the temperature and humidity. In particular, colorimetric sensors have attracted an interest [ 16 , 17 , 18 , 19 ] because they can minimize efforts associated with instrumentation and operation in detection, making them easily applicable to on-site detection [ 20 , 21 ]. The sensors mentioned above are preferable for prompt detection of gaseous pollutants.…”