Capillary ion analysis of lithium concentrations in biological fluids and tissues of Poecilia (teleost)

Capillary ion analysis (CIA) is a form of capillary electrophoresis that uses the differential electrophoretic mobility of ions to perform a separation of an ionic mixture. Application of this technique for detection of lithium concentrations in plasma and tissues of Poecilia was the purpose of this investigation. CIA was performed using a 75 microm ID x 60 cm length fused-silica capillary and a run electrolyte of 67.7 mg hydroxyisobutyric acid (HIBA), 52.8 mg 18-crown-6-ether and 64 microL UV-CAT-1 reagent (4-methylbenzylamine) in a volume of 100 mL water (18 (M)omega) with a voltage of 20 kV using ultraviolet absorption detection at 214 nm. Migration times were: potassium, 2.98 min; calcium, 3.48 min; sodium, 3.60 min; barium (internal standard), 4.15 min and lithium, 4.26 min. Lithium and barium migration times were stable and reproducible. Correlation coefficients (r) between peak area ratios of lithium/barium for concentrations ranging from 0.1 to 2.0 mM were from 0.976 to 0.996. Coefficients of variation (CV) for lithium concentrations ranged from 4.07 to 15.71% between days and 4.38 to 7.76% within-day. Application of this methodology for determination of lithium concentrations in the plasma, brains and livers of fish dosed with lithium for 23 days are presented. CIA is applicable to analysis of lithium concentrations in biological fluids and tissues of fish.