N-functionalization of pyrrole with carbon disulfide and subsequent chemical polymerization resulted in the development of a new sorbent material for the extraction of metals. The synthesized polymer, poly(pyrrole-N-carbodithioic acid) (PPy-CS2), is an air-stable, granular powder that is insoluble in water. PPy-CS2 combines pH-dependent chelation, extraction, and desorption sorbent properties that are exploited for the selective extraction and sensitive determination of heavy metals in water matrices using ultrasound-assisted dispersive micro solid-phase extraction and inductively coupled plasma mass spectrometry. Excellent removal and recovery of Cd(II), Co(II), Cu(II), Ni(II), Pb(II), and Zn(II) were achieved and compared with unfunctionalized polypyrrole, which demonstrated extraction resulted from chelation of the metal ions. The extraction efficiency of the PPy-CS2 sorbent as a function of pH, amount of sorbent, extraction time, and flow rate of the desorption solution were evaluated. Limits of detection ranged from 0.3 for cadmium to 11.2 ng/L for zinc with linear dynamic ranges from 0.1 to 500 μg/L and relative standard deviations from 2.2 to 6.3%. The sample preparation method was successfully applied for determination of the target metals in raw well water, treated well water, and river water. Validation was performed by analysis of a certified reference standard for trace metals in drinking water. Graphical abstract Schematic representation of the ultrasound-assisted micro solid-phase extraction protocol for the removal and recovery of heavy metals by the air-stable, granular, and reversible chelating polymer, poly (pyrrole-N-carbodithioic acid).
Keywords: Dispersive solid-phase extraction; Heavy metal determination; Inductively coupled plasma mass spectrometry; Sample preparation; Water analysis.