Selective Measurement of Ultratrace Methylmercury in Fish by Flow Injection On-Line Microcolumn Displacement Sorption Preconcentration and Separation Coupled with Electrothermal Atomic Absorption Spectrometry

Abstract

A novel nonchromatographic speciation technique for ultratrace methylmercury in biological materials was developed by flow injection microcolumn displacement sorption preconcentration and separation coupled on-line with electrothermal atomic absorption spectrometry (ETAAS). In the developed technique, Cu(II) was first on-line complexed with diethyldithiocarbamate (DDTC), and the resultant Cu-DDTC was presorbed onto a microcolumn packed with the sorbent from a cigarette filter. Selective preconcentration of methylmercury (MeHg) in the presence of Hg(II), ethylmercury (EtHg), and phenylmercury (PhHg) was achieved at pH 6.8 through loading the sample solution onto the microcolumn due to a displacement reaction between MeHg and the presorbed Cu-DDTC. The retained MeHg was subsequently eluted with 50 microL of ethanol and on-line determined by ETAAS. Interferences from coexisting heavy metal ions with lower stability of their DDTC complexes relative to Cu-DDTC were minimized without the need of any masking reagents. No interferences from 5.5 mg L(-1) Cu(II), 4.5 mg L(-1) Cd(II), 2.5 mg L(-1) Cr(III), 3 mg L(-1) Fe(III), 10 mg L(-1) Ni(II), 10 mg L(-1) Pb(II), and at least 25 mg L(-1) Zn(II) were observed for the determination of MeHg at the 50 ng L(-1) level (as Hg). With the consumption of only 3.4 mL of sample solution, an enhancement factor of 75, a detection limit of 6.8 ng L(-1) (as Hg) in the digest (corresponding to 3.4 ng g(-1) in original solid sample for a final 50 mL of digest of 0.1 g of solid material), and a precision (RSD, n = 13) of 2.3% for the determination of methylmercury at the 50 ng L(-1) (as Hg) level were achieved at a sample throughput of 30 samples h(-1). The recoveries of methylmercury spike in real fish samples ranged from 97 to 108%. The developed technique was validated by determination of methylmercury in a certified reference material (DORM-2, dogfish muscle), and was shown to be useful for the determination of methylmercury in real fish samples.

On-line coupling of solid-phase extraction to high-performance liquid chromatography for determination of estrogens in environment

“…Cigarette filter has been shown to have sorption to polycyclic aromatic hydrocarbons [62] in water and can be used to the determination of lead [63] in environmental and biological samples, and ultratrace methylmercury in fish [64]. But as far as our know, using cigarette filter to concentrate trace estrogens in water has not been reported, so the analytical characteristic parameters of cigarette filter as sorbent on-line microcolumn pre-concentration coupled with HPLC for the determination of trace estrogens were evaluated.…”

“…As far as we know, this article is the first report on the application of the SPE sorbent of the cigarette filter to determine estrogens in environmental water samples. It is well known that the cigarette filter can alleviate the poisonous effect on smokers, and recently it was proved that it could efficiently adsorb many poisonous organic compounds [62][63][64] in the water and biologic samples, such as polycyclic aromatic hydrocarbons, complex of lead, and ultratrace methylmercury. Therefore, the cigarette filter material was used as the sorbent for the pre-concentration and separation of estrogens in water samples.…”

Minimization of mass interferences in quadrupole inductively coupled plasma mass spectrometric (ICP-MS) determination of palladium using a flow injection on-line displacement solid-phase extraction protocol

“…In this work, the cigarette filter was selected as the sorbent owing to its powerful capability to adsorb neutral hydrophobic organo-metallic chelates and its superior properties such as good tenacity and intensity, and large surface area [15,16]. To design an efficient displacement solid-phase extraction protocol for selective separation of Pd 2+ , the dithiocarbamate stability of the displaced ion should be less than that of Pd 2+ , and higher than that of interfering ions.…”

“…The purpose of this work is to apply a recently developed flow injection (FI) on-line displacement solid-phase extraction technique [14][15][16] to eliminate/minimize major mass spectral interferences using a common complexing agent, ammonium pyrrolidine dithiocarbamate (APDC) with an easily available sorbent (cigarette filter) for selective and sensitive ICP-MS determination of trace palladium in rock samples.…”

Application of a novel strategy—Coordination polymerization precipitation to the treatment of Cu2+-containing wastewaters

“…from wastewater. Of these chelating metal precipitants, dithiocarbamate is the most common over the last 5 years [14][15][16]. The dithiocarbamate-type precipitants can be divided into two categories presently, macromolecular trapping agents and small molecular precipitants.…”