The use of capillary electrophoresisfor the study of the interaction of an insoluble polyampholyte with lithium cation

DEL RIO, LA; CINQUI, G; VIZIOLI, NM; LÁZARO MARTÍNEZ, JM; CAMPODALL'ORTO, V

Buenos Aires

Simposio; 18th Symposium on Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2012

Several salts of lithium are used medically as mood-stabilizing drugs, primarily in the treatment of bipolar disorder, where they have a role in the treatment of depression and mania, both acutely and in the long term. Lithium toxicity may occur in persons taking excessive amount either accidentally or intentionally, on an acute basis or in patients with chronic therapy. The manifestations include nausea, emesis, diarrhea, ataxia, confusion, lethargy, polyuria, seizures and coma. In this work, we evaluated the application of a synthetic plastic material highly functionalized for capture and release of lithium cation. The polymer was synthesized in a unique step from methacrylic acid, 2-methylimidazole, and ethylene glycol diglycidyl ether, and named poly(EGDE-MAA-2MI). In previous experiments, poly(EGDE-MAA-2MI) was chemically characterized and subjected to a safety test in mice, resulting innocuous when orally administered. For demonstrating its ability to capture Li+, the polymer was left in contact with non buffered aqueous solutions of Li+ (2.0 to 14 ppm) by 24 h. Lithium cation remaining in the solution was quantified by capillary zone electroforesis. A fused silica capillary (52 cm effective length, 75 μm id) was used. The background electrolyte consisted of 5 mM imidazole, 6.5 mM alpha-hydroxyisobutyric acid, pH 4.6. Samples were hydrodynamically introduced (0.5 psi, 5 s). A 10 kV voltage was applied. System temperature was set at 20 °C, and indirect UV detection was performed at 214 nm. A lineal relationship between the quantity of Li+ captured by the poly(EGDE-MAA-2MI) and Li+ concentration in the aqueous solution was observed. Saturation of the polymer was verified at 4 ppm Li+ at equilibrium (from a 10 ppm Li+ initial concentration), with a polymer maximum load capacity of 0.6 mg Li+/g. These results suggest the possibility of applying the polymeric material for capture of lithium cation during the treatment of overdose situations.