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Electromembrane extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection: Multi‐extraction capabilities to analyses trace metals from saline samples
Author(s) -
Silva Macarena,
Mendiguchía Carolina,
Moreno Carlos,
Kubáň Pavel
Publication year - 2018
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201800125
Subject(s) - chemistry , extraction (chemistry) , metal , capillary electrophoresis , repeatability , analytical chemistry (journal) , detection limit , conductivity , trace metal , acceptor , chromatography , seawater , inorganic chemistry , physics , organic chemistry , condensed matter physics , oceanography , geology
Abstract Simultaneous electromembrane extraction (EME) of six trace metal cations (Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Pb 2+ , Cd 2+ ) from saline samples was investigated. CE with capacitively coupled contactless conductivity detection (C 4 D) was used to determine the metals in acceptor solutions due to its excellent compatibility with the minute volumes of acceptor solutions. Bis(2‐ethylhexyl)phosphate (DEHPA) was selected as a suitable nonselective modifier for EME transport of target metal cations. Both, the individual effect of each major inorganic cation (Na + , K + , Ca 2+ , Mg 2+ ) and their synergistic effect on EME of the trace metal cations were evaluated. In both cases, a decrease in extraction efficiency was observed when major inorganic cations were present in the sample. This effect was more significant for Ca 2+ and Mg 2+ . The system was optimized for simultaneous extractions of the six target metals from saline samples (50 mM Na + , 5 mM Mg 2+ , 1 mM K + , and 1 mM Ca 2+ ) and following EME conditions were applied. Organic phase consisted of 1‐nonanol containing 1% (v/v) DEHPA, acceptor solution was 1 M acetic acid (HAc) and sample pH was adjusted to 5. Sample was stirred at 750 rpm and EMEs were carried out at extraction potential of 10 V for 20 min. The method presented a repeatability between 8 and 21.8% ( n = 5), good linearity in 0.5–10 μM concentration range ( R 2 = 0.987‐0.999) and LOD better than 2.6 nM. Applicability of the EME–CE–C 4 D method to the analyses of metal cations in drinking water, seawater, and urine samples was also demonstrated.