Separation of tocopherols by nano-liquid chromatography.
Nanoliquid chromatography (nano-LC) was used for the separation of tocopherols (delta-, gamma-, alpha-TOH), alpha-tocopherol acetate (alpha-TOH-Ac) and an antioxidant compound, namely butylated hydroxytoluene (BHT) used to prevent TOHs autoxidation. The separation was carried out in a fused silica capillary of 100 microm I.D. and 375 microm O.D. packed in our laboratory with RP18 silica stationary phase of either 5- or 3-microm diameter (23-cm long). The mobile phase was composed by mixtures of methanol (MeOH), acetonitrile (MeCN) and water. Typical analyses time for the separation of all the five components of the mixture were 6-9 min depending on the composition of the mobile phase. Efficiency and resolution were strongly influenced by the particle diameter and the highest Rs and N/m values were observed using 3-microm RP18 particles. Experiments performed with capillaries packed with 3-microm RP18 particles provided good limit of detection (LOD) and limit of quantification (LOQ) (for delta-, gamma-TOH, alpha-TOH-Ac were 4 and 8 microg/ml, while for alpha-TOH were 6 and 10 microg/ml, respectively). The optimized method was applied to extracts of serum and pharmaceutical preparation containing alpha-TOH and alpha-TOH-Ac.
Fanali
Salvatore
S
Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, P. O. Box 10, Area della Ricerca di Roma, Via Salaria Km 29,300, 00016 Monterotondo Scalo, Rome, Italy. fanali@imc.cnr.it
Camera
Emanuela
E
Chankvetadze
Bezhan
B
D'Orazio
Giovanni
G
Quaglia
Maria Giovanna
MG
D002853:Chromatography, Liquid / Q000379:methods*; D036103:Nanotechnology / Q000379:methods*; D024505:Tocopherols / Q000737:chemistry / Q000302:isolation & purification*
D024505:Tocopherols