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A novel QuEChERS-like method and apparatus of automatic sample pre-treatment for fast determination of mercury speciation in aquatic animal samples

Abstract

The accurate, stable and fast analysis of mercury speciation such as Hg2+, MetHg and EtHg in complicated aquatic animal matrix is always a challenge. Herein, an efficient analytical method of Hg species was developed using the QuEChERS-like approach followed by hydride generation liquid chromatograph atomic fluorescence spectrometry (LC-AFS). For the first time, a novel dual layer extracting tube consisting an outer tube (o-tube), an inner tube (i-tube), a cap for o-tube and a stopper for i-tube with a series of PVDF membranes was designed as an integrated tool of extracting and purifying Hg species, of which the membrane acted as a “valve” driven by the centrifuging force vs. membrane surface tension force. Here, the newly designed QuEChERS automated sample preparation system was responsible for the shaking and centrifugation of test samples. Aquatic animal samples were extracted with 10% HCl + 1% thiourea + 0.15% KCl solution in the o-tube by shaking at 800 rpm for 12 min; then, under the centrifuging force at 4000 rpm for 5 min, ~4 mL of analyte solution containing Hg species penetrated the membrane into the i-tube; by shaking at 600 rpm for 3 min and centrifuging at 4000 rpm for 2 min, pre-added 0.5 mL chloroform in the i-tube was employed to remove the protein and lipid in matrix for purifying Hg species; finally, the upper layer extract in the i-tube was able to be measured by LC-AFS without extra processing. Under the optimum conditions, from 5 μg/L to 1000 μg/L, the linear regression coefficient (R2) was > 0.998; the spiked recoveries of Hg2+, MetHg and EtHg in aquatic animal samples were in the 88% - 104% range, and the method can achieve desirable limits of detection below 3 μg/kg. The relative standard deviations (RSD) were < 10% for 10 μg/kg standards and real samples including fish, obster, scallop and carp, which proved an acceptable precision. The proposed QuEChERS-like LC-AFS method is extremely suitable for Hg2+, MetHg and EtHg determination in aquatic animal samples with advantages of simplicity, quickness, accuracy, high-sensitivity and minimum personal error, to protect public health against mercury hazards.

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Publication details

The article was received on 30 Sep 2018, accepted on 06 Dec 2018 and first published on 06 Dec 2018


Article type: Paper
DOI: 10.1039/C8JA00323H
Citation: J. Anal. At. Spectrom., 2018, Accepted Manuscript
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    A novel QuEChERS-like method and apparatus of automatic sample pre-treatment for fast determination of mercury speciation in aquatic animal samples

    X. Zhang, Y. Liu, Z. Zhang, X. Na, X. Mao, J. Liu, T. Liu, M. Liu and Y. Qian, J. Anal. At. Spectrom., 2018, Accepted Manuscript , DOI: 10.1039/C8JA00323H

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