Isonicotinic acid hydrazide-based silver nanoparticles as simple colorimetric sensor for the detection of Cr3+

• We used INAH-based AgNPs as simple colorimetric sensor for Cr3+ for the first time.
• The AgNPs were synthesized by one step approach using INAH and citrate.
• The Cr3+induced aggregation of AgNPs were analyzed by UV–vis spectrophotometer.
• This method exhibited good sensitivity and selectivity for the assay of Cr3+.

A simple colorimetric method for the detection of Cr3+ is proposed using silver nanoparticles (AgNPs) prepared with isonicotinic acid hydrazide (INAH) and sodium citrate. The AgNPs were synthesized via a one-step approach at room temperature using INAH as reducing agent in the presence of sodium citrate. As synthesized AgNPs showed a characteristic UV absorption band at 403 nm. The AgNPs exhibited an excellent response with regard to colorimetric sensing of Cr3+ as a result of their surface modification. No such response was observed in case of AgNPs prepared in the absence of INAH. It is proposed that INAH as isonicotinic acid (INA) and citrate on the surfaces of AgNPs interact cooperatively with the Cr3+ ions, resulting in aggregation of AgNPs in the solution. The aggregation induced by the addition of Cr3+ to the AgNPs containing solution leads to turn the color of a solution from golden yellow to red along with a remarkable change in absorption band. The color change was readily detectable with the naked eye even at lower concentration of Cr3+. The spectral change was monitored by UV–vis spectroscopy. Under optimized conditions, the sensor demonstrated a good linear relationship between absorption ratios and the Cr3+ concentrations in the range of 1 × 10−6 to 5 × 10−5 M with correlation coefficient (R2) of 0.993, and detection limit of 4.5 × 10−7 M for the colorimetric assay. In addition, the developed sensor showed high selectivity for Cr3+ in the presence of other common heavy metal ions. This method enabled the rapid determination of Cr3+ in tap and river water samples within the acceptable range of recoveries.

Schematic illustration of INA-cit-AgNPs based colorimetric detection of Cr3+.Figure optionsDownload as PowerPoint slide