Spectrophotometric and colorimetric trivalent chromium ions detection in aqueous solution based on citrate-capped gold nanoparticles

In this work, citrate-capped gold nanoparticles (AuNPs) were utilized as colorimetric probe to detect trivalent chromium ions (Cr3+) in aqueous solution. The optimal detection conditions were investigated, such as pH and reaction time and so on. The result showed that citrate-capped AuNPs would be aggregated when Cr3+ ions existed, meanwhile, the colorimetric reaction occurred change from red to violet when pH was 8. According to that mechanism, Cr3+ ions were determined via naked eye and UV-vis spectrum. The reaction time was fast for 25 min. There was a curve relationship of the ratio of the absorbance observed at 675 nm and 520 nm (A675 nm/A520 nm) from 1 to 11 mu M. The limit of detection can reach 0.9 mu M. Besides, this platform exhibited high specificity for Cr3+ ions. The platform had a great practical value for heavy metal ions detection.

Automated summary

In this study, citrate-capped gold nanoparticles were used as a colorimetric probe for the detection of trivalent chromium ions in aqueous solution. The optimal detection conditions, such as pH and reaction time, were investigated. The results showed that the gold nanoparticles would aggregate in the presence of Cr3+ ions, and the colorimetric reaction changed from red to violet at pH 8. The Cr3+ ions were determined using naked eye and UV-vis spectrum, with a fast reaction time of 25 minutes. The platform exhibited a curve relationship between the absorbance ratio at 675 nm and 520 nm, with a detection limit of 0.9 μM. Additionally, the platform demonstrated high specificity for Cr3+ ions and held significant practical value for heavy metal ion detection.