A capillary electrophoretic (CE) method using a short-sweep approach and laser-induced fluorescence (LIF) detection (ShortSweepCE-LIF) was developed for determination of Zn2+ and Cd2+ as complexes with highly selective and sensitive fluorescent probe FluoZin-3. The ShortSweepCE-LIF method, established in this work, can be used for examining competitive Zn2+ and Cd2+ binding properties of metalloproteins or peptides. The parameters including background electrolyte composition, injection pressure and time as well as separation voltage were investigated. Under the optimized conditions, 80 mM HEPES, pH 7.4, with 1.5 μM FluoZin-3 was used as an electrolyte, hydrodynamic injection was performed at 50 mbar for 5 s, and separation voltage of 25 kV. Limits of detection for Zn2+ and Cd2+ were 4 and 125 nM, respectively. The developed method was demonstrated in a study of interactions between metalothionein-2a isoform and metal ions Zn2+, Co2+ and Cd2+. It was found that FluoZin-3 was able to extract a single Zn2+ ion, while added Co2+ (in surplus) extracted only 2.4 Zn2+ ions, and Cd2+ extracted all 7 Zn2+ ions present in the metalothionein molecule.

• Klíčová slova
• Cadmium, Capillary electrophoresis, FluoZin-3, Metal ions, Metalothionein, Zinc,
• MeSH
• elektroforéza kapilární MeSH
• fluorescenční barviva chemie   MeSH
• ionty analýza   MeSH
• kadmium analýza   MeSH
• metalothionein analýza   MeSH
• optické zobrazování * MeSH
• polycyklické sloučeniny chemie   MeSH
• zinek analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fluorescenční barviva MeSH
• FluoZin-3 MeSH Prohlížeč
• ionty MeSH
• kadmium MeSH
• metalothionein MeSH
• polycyklické sloučeniny MeSH
• zinek MeSH

By virtue of their compactness, long-term stability, minimal reagent consumption and robustness, miniaturized sequential injection instruments are well suited for automation of assays onboard research ships. However, in order to reach the sensitivity and limit of detection required for open-ocean determinations of trace elements, it is necessary to preconcentrate the analyte prior its derivatization and subsequent detection by fluorescence. In this work, a novel method for the determination of dissolved zinc (Zn) at subnanomolar levels in seawater is described. The proposed method combines, for the first time, automated matrix removal, extraction of the target element, and fluorescence detection within a miniaturized flow manifold, based on the Lab-On-Valve (LOV) concept. The key feature of the microfluidic manipulation of the sample is flow programming, designed to pass sample through a mini-column where the target analyte and other complexable cations are retained, while the seawater matrix is washed out. Next, zinc is eluted and merged with a Zn selective fluorescent probe (FluoZin-3) at the confluence point of the LOV central channel using two high-precision stepper motor driven pumps that are operated in concert. Finally, the thus formed Zn complex is transported to the LOV flow cell for selective fluorescence measurement. This work describes the characterization and optimization of the method including Solid Phase Extraction using the Toyopearl AF-Chelate-650M resin, and detailed assay protocol controlled by a commercially available software and instrument. The proposed method features a LOD of 0.02 nM, high precision (<3% at 0.1 and 2 nM Zn levels), an assay cycle of 13 min and a reagent consumption of 150 μL FluoZin-3 per sample, which makes the method highly suitable for oceanographic shipboard analysis. The accuracy of the method has been validated through the analysis of seawater reference standards and comparison with ICP-MS determinations on seawater samples collected in the upper 1300 m of the subtropical south Indian Ocean. This work confirms that integration of sample pretreatment with optical detection in the LOV format offers a widely applicable approach to trace analysis of seawater.

• Klíčová slova
• FluoZin-3, GEOTRACES, Lab-On-Valve, Oceanography, Trace analysis, Zn,
• MeSH
• extrakce na pevné fázi metody   MeSH
• fluorescenční barviva chemie   MeSH
• fluorescenční spektrometrie metody   MeSH
• limita detekce MeSH
• miniaturizace MeSH
• mořská voda chemie   MeSH
• polycyklické sloučeniny chemie   MeSH
• referenční standardy MeSH
• stopové prvky analýza   MeSH
• zinek analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fluorescenční barviva MeSH
• FluoZin-3 MeSH Prohlížeč
• polycyklické sloučeniny MeSH
• stopové prvky MeSH
• zinek MeSH