Development of a new hybrid technique for rapid speciation analysis by directly interfacing a microfluidic chip-based capillary electrophoresis system to atomic fluorescence spectrometry

Abstract

This paper represents the first study on direct interfacing of microfluidic chip-based capillary electrophoresis (chip-CE) to a sensitive and selective detector, atomic fluorescence spectrometry (AFS) for rapid speciation analysis. A volatile species generation technique was employed to convert the analytes from the chip-CE effluent into their respective volatile species. To facilitate the chip-CE effluent delivery and to provide the necessary medium for subsequent volatile species generation, diluted HCl solution was introduced on the chip as the makeup solution. The chip-CE-AFS interface was constructed on the basis of a concentric "tube-in-tube" design for introducing a KBH4 solution around the chip effluent as sheath flow and reductant for volatile species generation as well. The generated volatile species resulting from the reaction of the chip-CE effluent and the sheath flow were separated from the reaction mixture in a gas-liquid separator and swept into the AFS atomizer by an argon flow for AFS determination. Inorganic mercury (Hg(II)) and methylmercury (MeHg(I)) were chosen as the targets to demonstrate the performance of the present technique. Both mercury species were separated as their cysteine complexes within 64 s. The precision (relative standard deviation, RSD, n = 5) of migration time, peak area, and peak height for 2 mg.L(-1) Hg(II) and 4 mg.L(-1) MeHg(I) (as Hg) ranged from 0.7 to 0.9%, 2.1 to 2.9%, and 1.5 to 1.8%, respectively. The detection limit was 53 and 161 microg.L(-1) (as Hg) for Hg(II) and MeHg(I), respectively. The recoveries of the spikes of mercury species in four locally collected water samples ranged from 92 to 108%.

Determination of mercury(II) in water samples using dispersive liquid-liquid microextraction and back extraction along with capillary zone electrophoresis

“…In addition, compared with generally recognized element specific detection methods, such as atomic absorption spectrometry (AAS) [36], atomic fluorescence spectrometry (AFS) [37] and amperometry [39], coupled to off-column derivatization [36,37] or ion exchange (IE) [39], the developed method still offered about 3 and 85 times higher sensitivity with high precision in a short time.…”

“…The CZE separation conditions were investigated, such as the nature, concentration, pH value of the electrophoresis buffer, the applied voltage and the sample injection time. The boric acid and methanol system was mostly used according to previous reports [37,38,41]. In this work, the buffer pH, the concentration of boric acid and methanol in the buffer solution were examined.…”

“…Effect of L-Cys volume L-Cys of 0.1% (w/v) was chosen as the extraction solvent as reported [37,38]. In this process, Hg 2+ formed more hydrophilic and stable complex with LCys over its PAN counterpart [38].…”

DNA binding in combination with capillary electrophoresis and inductively coupled plasma mass spectrometry for the rapid speciation analysis of mercury

“…For example, HPLC or GC or CE hyphenated with atomic fluorescence spectrometry (AFS) or inductively coupled plasma mass spectrometry (ICP-MS) [4][5][6][7][8][9][10][11][12][13][14][15][16]. Among all above hyphenated techniques, CE-ICP-MS has attracted increasing attention since CE has higher separation efficiency for all ionic and neutral species, tiny sample requirement, various separation modes and low operating cost [17][18][19], and ICP-MS has short detection time, broad dynamic range, multi-element capabilities, excellent mass resolution and high sensitivity for almost metallic ions.…”

A low‐leakage sample plug injection scheme for crossform microfluidic capillary electrophoresis devices incorporating a restricted cross‐channel intersection

“…Today's state-of-the-art micromachining techniques enable a network of microfluidic devices to be fabricated on a single glass [8][9][10], poly(methyl methacrylate) (PMMA) [11,12], PDMS [13,14], polycarbonate (PC) [15,16], or quartz [17] substrate and therefore make possible the realization of complete chemical or biological analysis systems on a single platform. Such systems are commonly referred to as micro-total analysis systems (m-TAS) or lab-on-a-chip (LoC) devices [18][19][20][21][22][23][24][25] and typically integrate multiple functional units designed to carry out sample separation and collection, DNA restriction, sample manipulation and mixing, DNA amplification, PCR, cell sorting and counting, mixing, clinical and forensic analysis, online detection, and so forth.…”