POSSIBLE USES OF MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY ANDHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY FOR THE CHIRAL DISCRIMINATION OF SOME PYRETHROIDS
J. Sevcik et al., POSSIBLE USES OF MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY ANDHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY FOR THE CHIRAL DISCRIMINATION OF SOME PYRETHROIDS, Chirality, 9(2), 1997, pp. 162-166
Micellar electrokinetic capillary chromatography (MECC) and highperfor
mance liquid chromatography (HPLC) were used for the separation of ste
reoisomers of the lipophilic uncharged pyrethroids cypermethrin, alpha
methrin, permethrin, and fenpropathrin. Different kinds of cyclodextri
n (beta-cyclodextrin, hydroxypropyl-beta-cyclodextrin, dimethyl-beta-c
yclodextrin, and gamma-cyclodextrin), surfactants (sodium dodecyl sulp
hate [SDS] and cetyltrimethylammonium bromide [CTAB]), and cations of
background electrolyte (sodium, ammonium, TRIS, and Ammediol) were tes
ted. Optimized conditions (background electrolyte: 50 mmol/l sodium ph
osphate, pH = 2.5, 150 mmol/l SDS, 150 mg/ml gamma-cyclodextrin) allow
ed the separation of alphamethrin, the eight cypermethrin stereoisomer
s being eluted in seven peaks and the separation of two enantiomers of
fenpropathrin with resolution R-s = 10 and with n approximate to 500,
000 theoretical plates. Different experimental conditions, e.g., mobil
e phase composition, temperature, injected amount, and flow rate, were
also optimized in HPLC experiments. The optimal conditions (stationar
y phase: ChiraDex, 5 mu m; mobile phase: 150 mmol triethylamine/l with
H2SO4 in water (pH = 3.5) with methanol or acetonitrile; now rate: 0.
8 or 0.6 ml/min; temperature: ambient or 30 degrees, 20 degrees, or 10
degrees C; experimental conditions were modified according to the typ
e of analysis) allow chiral discrimination of alphamethrin enantiomers
and analysis of permethrin stereoisomers. MECC offers higher efficien
cy and shorter analysis time than HPLC, but under tested conditions it
was shown that the methods complement each other. (C) 1997 Wiley-Liss
, Inc.