Selected Article

Title

Influence of phosphate buffer and proteins on the potentiometric response of a polymeric membrane-based solid-contact Pb(II) ion-selective electrode

Description

In this work, the influence of phosphate buffer and proteins on the potentiometric response of a polymeric membrane-based solid-contact Pb

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2+

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-selective electrode (Pb

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2+

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-ISE) was studied. The effects of bovine serum albumin (BSA) adsorption at the surface of the ion-selective membrane combined with electrode conditioning in phosphate-buffered saline (PBS) solution was elucidated by potentiometry and electrochemical impedance spectroscopy. The adsorbed BSA at the surface of the Pb

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2+

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/sup

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-ISE slightly lowered the detection limit but did not influence the selectivity of the Pb

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2+

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/sup

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-ISE towards the interfering ions studied (Cu

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2+

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, Cd

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2+

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). Conditioning of the Pb

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2+

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/sup

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-ISE in 0.01 mol dm

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–3

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/sup

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PBS resulted in a super-Nernstian response which was related to fixation/extraction of Pb

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2+

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/sup

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in the ion-selective membrane via precipitation of Pb

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sub

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3

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(PO

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4

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/sub

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)

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2

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by PO

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4

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3–

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anions present in PBS. By conditioning of the Pb

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2+

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-ISE in 0.01 mol dm–3 PBS + 1 mg/ml BSA it was possible to extend the linear response range of the Pb

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2+

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-ISE towards lower analyte concentrations. The utilization of this conditioning procedure was validated by determination of Pb

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2+

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/sup

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concentrations down to ca 20 ppb in aqueous samples by Pb

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2+

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-ISEs and by comparing the results with those obtained by ICP-MS.