Direct fluorescence detection of ultratrace lanthanide(III) ions complexed with aromatic polyaminocarboxylate, avoiding quenching of ligand-centered emission, using capillary zone electrophoresis with a ternary complexing technique.
The ultratrace level detection and the separation of lanthanide ions (Ln3+) were achieved using capillary zone electrophoresis with laser induced fluorescent detection (CZE-LIF) using an aromatic polyaminocarboxylate ligand synthesized in our previous work. The ligand forms kinetically stable Ln complexes at the pre-capillary derivatizing step. It effectively avoids quenching processes of the ligand-centered fluorescence through complexation with Ln3+ without paramagnetic and heavy atom effects because of the distance between the chelating and the antenna moieties. During the on-capillary separation step, the mother Ln complexes competitively form ternary complexes with the auxiliary ligands, iminodiacetate and citrate, which provide different mobilities for each of the Ln3+ complexes. The emissively labeled Ln3+ complexes were efficiently separated, based on the ternary complex equilibrium. Since the carrier buffer employed was free from emissive ligands, a high signal to noise ratio was obtained. A lower detection limit of 9.1 x 10(-11) mol dm(-3) (15.6 ng dm(-3), 0.46 attomole as an amount basis) was successfully achieved typically for Lu3+ with a simple CZE mode. We propose a combination of a pre-capillary and an on-capillary complexing technique as a method that provides both high sensitivity and high resolution.
Saito
Shingo
S
Department of Applied and Environmental Chemistry, Kitami Institute of Technology, Kitami, Hokkaido, 090-8507, Japan. shingo@chem.kitami-it.ac.jp
Takeuchi
Shingo
S
Yoshimoto
Keitaro
K
Maeda
Mizuo
M
Aoyama
Masakazu
M
D000085:Acetates / Q000737:chemistry*; D002021:Buffers; D019075:Electrophoresis, Capillary / Q000379:methods*; D005029:Ethylenediamines / Q000737:chemistry*; D005453:Fluorescence; D028581:Lanthanoid Series Elements / Q000032:analysis*; D007834:Lasers; D008024:Ligands; D013050:Spectrometry, Fluorescence / Q000379:methods
C509200:1-(4-aminobenzyl)ethylenediamine-N,N,N',N'-tetraacetate; D000085:Acetates; D002021:Buffers; D005029:Ethylenediamines; D028581:Lanthanoid Series Elements; D008024:Ligands