Tocols were separated isocratically within 20 min using a mobile phase containing 3% 1,4-dioxane and 97% nheptane (v/v) and a flow rate of 2 ml/min, and detected fluorimetrically (l
ex
3.8 tr 1.3
tr 312 1.2 Margarine F/1 40 178 1.9
b
3.2 251 3.0
b
18 4.2 2.3
b
6.5
b
: 290 nm, l
tr 2.4
1.1 512 1.6 Rolling fat G/1 12 63 2.4
Rolling fat H/2 14 58 6.2
b
b
5.6 97 3.9 5.9 2.1 1.0
4.8 87 1.3
b
b
: 325 nm) (Kamal-Eldin et al., 2000). Dissolved air was removed from the mobile phase both by sonication prior to analysis and onlinehelium degassing. The column was kept at 30 1C and the autosampler tray was cooled to 4 1C.solutions were checked every month by spectrophotometric measurements. Every 2 weeks, four working solutions containing all four tocopherols at concentrations of 0.2, 2, 5 and 20 mg/l were prepared in heptane and stored in volumetric flasks wrapped with aluminium foil and sealed with parafilm at 4 1C.