A dipole-assisted solid-phase extraction microchip combined with inductively coupled plasma-mass spectrometry for online determination of trace heavy metals in natural water

Abstract

We employed a polymeric material, poly(methyl methacrylate) (PMMA), for fabricating a microdevice and then implanted the chlorine (Cl)-containing solid-phase extraction (SPE) functionality into the PMMA chip to develop an innovative on-chip dipole-assisted SPE technique. Instead of the ion-ion interactions utilized in on-chip SPE techniques, the dipole-ion interactions between the highly electronegative C-Cl moieties in the channel interior and the positively charged metal ions were employed to facilitate the on-chip SPE procedures. Furthermore, to avoid labor-intensive manual manipulation, a programmable valve manifold was designed as an interface combining the dipole-assisted SPE microchip and inductively coupled plasma-mass spectrometry (ICP-MS) to achieve the fully automated operation. Under the optimized operation conditions for the established system, the detection limits for each analyte ion were obtained based on three times the standard deviation of seven measurements of the blank eluent solution. The limits ranged from 3.48 to 20.68 ng L(-1), suggesting that this technique appears uniquely suited for determining the levels of heavy metal ions in natural water. Indeed, a series of validation procedures demonstrated that the developed method could be satisfactorily applied to the determination of trace heavy metals in natural water. Remarkably, the developed device was durable enough to be reused more than 160 times without any loss in its analytical performance. To the best of our knowledge, this is the first study reporting on the combination of a dipole-assisted SPE microchip and elemental analysis instrument for the online determination of trace heavy metal ions.

Fabrication of a Dipole-assisted Solid Phase Extraction Microchip for Trace Metal Analysis in Water Samples

“…The detailed analytical results for water samples collected from two rivers in Taiwan have been described elsewhere. 16 To the best of our knowledge, this is the first attempt to utilize an innovative working strategy in on-chip SPE reaction for the determination of trace metal ions, and that the developed device was significantly durable compared with other on-chip SPE techniques (i.e., more than 160 analytical works could be achieved without significant deterioration in terms of the extraction efficiency). Nevertheless, because such extraction mechanism was mainly relied on the interactions between the highly electronegative C-Cl moieties and the positively charged metal ions, the proposed technique was expected to be unsuited for the extraction of the negatively charged species so far.…”

Fabrication of a Dipole-assisted Solid Phase Extraction Microchip for Trace Metal Analysis in Water Samples

“…Remove the residual solution and then rinse the PMMA powders in each well with 1 ml ethanol. 16. Remove the residual solution and then rinse the PMMA powders in each well with 1 ml D. I. H 2 O.…”

EDTA-Silane Modified Magnetite Core-Shell Nanoparticles as a Solid Phase Extraction Sorbent for the Determination of Pb and Cd in Environmental Water Samples Coupled With Hydride Generation Atomic Fluorescence Spectrometry

“…But the direct determination of trace metal ions is often limited due to their low concentration and strong interference from the real sample matrices. In order to prevent these limitations, preliminary pre-concentration and separation procedures are essential and have been applied prior to instrumental determination, such as co-precipitation (9), solvent extraction (10), cloud point extraction (CPE) (11), solid-phase extraction (SPE) (12,13), and magnetic solid-phase extraction (MSPE) (14,15).…”