Valproate-Selective Membrane Electrode Based on Gallium(III) Tetraphenylporphyrin

• Published in: Electroanalysis (New York, N.Y.) Vol. 12; no. 16; pp. 1282 - 1285
• Main Authors: Katsu, Takashi, Ido, Kazuyuki, Moriya, Aki, Nakae, Yoshinori, Sakata, Isao
• Format: Journal Article
• Language: English
• Published: Weinheim VCH Verlagsgesellschaft mbH 01.11.2000
• Subjects: Blood analysis; Drug monitoring; Gallium(III) tetraphenylporphyrin; Ion-selective electrode; Valproate determination
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/1521-4109(200011)12:16<1282::AID-ELAN1282>3.0.CO;2-D

Gallium(III) tetraphenylporphyrin (GaTPP) was found to act as an ionophore for valproate, an agent widely used for anti‐epileptic therapy. An electrode constructed using GaTPP and bis(1‐butylpentyl)decane‐1,10‐diyl diglutarate (ETH 469) as a membrane solvent in a poly(vinyl chloride) membrane matrix exhibited a near‐Nernstian response to valproate in the concentration range 5×10–5–1×10–2 M with a slope of –55 mV per concentration decade in a buffer solution containing 0.1 M 2‐morpholinoethanesulfonic acid (MES)‐NaOH (pH 5.5). The lower limit of detection was 20 µM. The electrode displayed the following selectivity sequence: valproate>salicylate> SCN–>benzoate>ClO4–≈F–>NO2–>CH3COO–≈I–>Cl–>NO3–. This electrode was applied to the determination of valproate levels in deproteinized serum samples.