Determination of Lead (II) Concentration Using Iminodiacetic Acid-Modified Silver Nanoparticles by Highly Sensitive SERS Technique

Abstract

A system for the highly sensitive detection of Pb[Formula: see text] ions by surface-enhanced Raman scattering (SERS) was designed based on silver nanoparticles (AgNPs) capped with iminodiacetic acid (IDA)/4-mercaptopyridine (4-MPY). In this system, IDA was absorbed on the surface of the AgNPs to induce the coupling of Pb[Formula: see text] ions for aggregation in the aqueous solution. 4-MPY, which was also attached to the surface of the AgNPs, was used as a Raman reporter. When the concentration of Pb[Formula: see text] ions increased, a stronger 4-MPY Raman signal was detected. The IDA and 4-MPY concentrations were adjusted to maximize the 4-MPY Raman signal. Under this optimal condition, the concentration of Pb[Formula: see text] ions had a linear relationship with 4-MPY Raman signal in the range of 1[Formula: see text][Formula: see text][Formula: see text]108 to [Formula: see text][Formula: see text]mol/L ([Formula: see text]). The limit of detection (LOD) of 1.816[Formula: see text]nmol/L was obtained, which is significantly lower than the World Health Organization’s (WHO) defined limit of 100[Formula: see text][Formula: see text]g/L in drinking water. This system was successfully applied to determine the Pb[Formula: see text] concentration in a contaminated water sample, which is obtained by adding a trace of Pb[Formula: see text] ions to drinking mineral water. The results proved that the IDA/4-MPY-modified AgNPs sensing system had a potential application for the Pb[Formula: see text] measurement with high sensitivity and excellent selectivity.