Magnetic nano-adsorbent integrated with lab-on-valve system for trace analysis of multiple heavy metals

Abstract

A novel system for trace analysis of multiple heavy metals was developed wherein we have integrated a magnetic nano-adsorbent with a lab-on-valve system and coupled this to an inductively coupled plasma mass spectrometer. The magnetic nano-adsorbent was prepared by surface modification of iron-based magnetic nanoparticles with polyacrylic acid (MNPs-PAA). The MNPs-PAA possessing the superparamagnetic nature of MNPs could be controllably immobilized in PTFE tubing by an external magnetic force. The high surface density of PAA (3.30 Â 10 11 molecules cm À2 ) on MNPs-PAA significantly reduced the amounts of adsorbent needed for adsorption of heavy metals (Mn 2+ , Co 2+ , Cu 2+ , Zn 2+ , and Pb 2+ ). A detection limit of 0.04-0.06 mg L À1 (except 0.6 mg L À1 for Cu 2+ and Zn 2+ ), a precision smaller than 4% (RSD, n ¼ 3), and a linear range of 0.5-50 mg L À1 were obtained by directly injecting an aliquot of 20 mL fortified standard solution analyzed at 5 min per sample. The accuracy was evaluated by analyzing certified reference materials of SRM 2670a (trace elements in urine, low level) and CASS-2 (nearshore seawater reference material for trace metals). Good agreement between the measured and certified values demonstrated that the system is useful for trace analysis of multiple heavy metals in environmental and biological aqueous samples. The potential of integrating functionalized nano-materials to improve the performance of existing analytical systems as an alternative approach to green analytical chemistry is foreseen.

Polymeric hydrogels modified with ornithine and lysine: Sorption and release of metal cations and amino acids

“…The internal structure of the gel becomes denser, which makes the penetration of the gel by subsequent ions harder, and limits the spatial orientation of the amino acid groups suitable for the formation of complexes of 1:2 stoichiometry. The sorption capacities obtained by us are higher than those reported recently for carbon nanotubes47 as well as for various chelate‐functionalized materials such as iron‐based magnetic nanoparticles with polyacrylic acid48 and imprinted polymethacrylic microbeads with 4‐(2‐pyridylazo) resorcinol 49. They are comparable with those reported recently for polymeric hydrogels containing the chelating groups 50–53…”

Greening Sampling Techniques

“…Nanoparticles can be used for direct analyte extraction and preconcentration from liquid samples such as water [22], seawater [23] and urine [23], with practically untreated samples increasing analytical probes' or sensors' sensitivity or selectivity, especially in the case of electrochemical sensors [24]. Nanoparticles can be used for direct analyte extraction and preconcentration from liquid samples such as water [22], seawater [23] and urine [23], with practically untreated samples increasing analytical probes' or sensors' sensitivity or selectivity, especially in the case of electrochemical sensors [24].…”

Tuning Interfacial Energy Barriers in Heterojunctions for Anti‐Interference Sensing

“…[ 1 ] Some sophisticated pretreatments of the samples, such as digestion, separation, and purification, are thus needed to minimize these matrix effects, which makes detection complicated and time consuming. [ 2,3 ] Therefore, it is urgent and challenging to achieve a high selectivity for electrochemical sensors.…”