Microemulsion electrokinetic chromatography applied for separation of levetiracetam from other antiepileptic drugs in polypharmacy.
Microemulsion electrokinetic chromatography was applied for the separation of levetiracetam from other antiepileptic drugs (primidone, phenobarbital, phenytoin, lamotrigine and carbamazepine) that are potentially coadministered in therapy of patients. The influence of the composition of the microemulsion system (with sodium dodecyl sulfate as charged surfactant) was investigated, modifying the kind of cosurfactant (lower alcohols from C3 to C5), the pH (and salinity) of the aqueous background electrolyte, and the ratio of aqueous phase to organic constituents forming the microdroplets of the oil-in-water emulsion. Separation selectivity was depending on all these parameters, resulting even in changes of the migration sequence of the analytes. Only moderate correlation was observed for the microemulsion system compared with a micellar system, both consisting of the aqueous borate buffer (pH 9.2) and SDS as micelle former (linear correlation coefficient for analyte mobilities is 0.974). The sample solvent plays an important role on the shape of the resulting chromatograms: methanol at concentrations higher than 35% impairs peak shape and separation efficiency. The microemulsion method (with 93.76% aqueous borate buffer (pH 9.2, 10 mM), 0.48% n-octane, 1.80% SDS, 3.96% 1-butanol, all w/w) is suitable for the determination of levetiracetam in human plasma (combined with a sample pretreatment based on solid-phase extraction).
Ivanova
Mariela
M
Institute for Analytical Chemistry, University of Vienna, Vienna, Austria.
Piunti
Alessandra
A
Marziali
Ettore
E
Komarova
Natalja
N
Raggi
Maria Augusta
MA
Kenndler
Ernst
E
D000927:Anticonvulsants / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D004338:Drug Combinations; D004655:Emulsions / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D000077287:Levetiracetam; D009994:Osmolar Concentration; D010889:Piracetam / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry
D000927:Anticonvulsants; D004338:Drug Combinations; D004655:Emulsions; D012997:Solvents; D013501:Surface-Active Agents; D000077287:Levetiracetam; D010889:Piracetam