Determination of iodide in samples with complex matrices by hyphenation of capillary isotachophoresis and zone electrophoresis.
A method has been developed for the determination of iodide in mineral water, seawater, cooking salt, serum, and urine based on hyphenation of capillary ITP and zone electrophoresis. A commercially available instrumentation for capillary ITP with column-switching system was used. ITP served for removal of chloride present in the analyzed samples in a ratio of 10(6)-10(7):1 to iodide, zone electrophoresis was used for evaluation. Isotachophoretic separation proceeded in a capillary made of fluorinated ethylene-propylene copolymer of 0.8 mm id and 90 mm total length to the bifurcation point filled with a leading electrolyte (LE) composed of 8 mM HCl + 16 mM beta-alanine (beta-Ala) + 10% PVP + 2.86 mM N(2)H(4)x2HCl, pH 3.2; and a terminating electrolyte composed of 8 mM H(3)PO(4) + 16 mM beta-Ala + 10% PVP + 5 mM N(2)H(4), pH 3.85 for all the matrices except seawater. For ITP of seawater the LE consisted of 50 mM HCl + 100 mM beta-Ala + 10% PVP + 2.86 mM N(2)H(4)x2HCl, pH 3.52. Distance of conductivity detector from the injection point and bifurcation point was 52 and 38 mm, respectively. Zone electrophoresis was performed in a capillary made of fused silica of 0.3 mm id and 160 mm total length filled with LE from isotachophoretic step. LODs reached for all matrices were 2-3x10(-8) M concentration (2.5-4 microg/L) enabled monitoring of iodide in all analyzed samples with RSD 0.4-9.3%. Estimated concentrations of iodide in individual matrices were 10(-6)-10(-8) M.
Pantůcková
Pavla
P
Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Urbánek
Marek
M
Krivánková
Ludmila
L
D004586:Electrophoresis / Q000379:methods; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007454:Iodides / Q000097:blood* / Q000652:urine*; D008900:Mineral Waters / Q000032:analysis*; D012623:Seawater / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
D007454:Iodides; D008900:Mineral Waters