[F1Determination of the linear speed of the gas U.K.
With the gas chromatograph set to normal operating conditions, inject 1 to 3 μl of methane (or propane) and measure the time taken by the gas to pass through the column, from the time of injection to the time at which the peak appears (tM).
The linear speed in cm/s is given by L/tM, where L is the length of the column in centimetres and tM is the measured time, in seconds.
Table 1
Relative retention times for sterols
| Peak | Identification | Relative retention time | ||
|---|---|---|---|---|
| SE 54 column | SE 52 column | |||
| 1 | Cholesterol | Δ-5-cholesten-3 ß -ol | 0,67 | 0,63 |
| 2 | Cholestanol | 5 α -cholestan-3 ß -ol | 0,68 | 0,64 |
| 3 | Brassicasterol | [24S]-24-methyl-Δ-5,22-cholestadien-3 ß -ol | 0,73 | 0,71 |
| * | Ergosterol | [24S] 24 methy Δ5-7-22 cholestatrien 3ß-ol | 0,78 | 0,76 |
| 4 | 24-methylene-cholesterol | 24-methylene-Δ-5,24-cholestadien-3 ß -o1 | 0,82 | 0,8 |
| 5 | Campesterol | (24R)-24-methyl-Δ-5-cholesten-3 ß -ol | 0,83 | 0,81 |
| 6 | Campestanol | (24R)-24-methyl-cholestan-3 ß -ol | 0,85 | 0,82 |
| 7 | Stigmasterol | (24S)-24-ethyl-Δ-5,22-cholestadien-3 ß -ol | 0,88 | 0,87 |
| 8 | Δ-7-campesterol | (24R)-24-methyl-Δ-7-cholesten-3 ß -ol | 0,93 | 0,92 |
| 9 | Δ-5,23-stigmastadienol | (24R,S)-24-ethyl-Δ-5,23-choIestadien-3 ß -ol | 0,95 | 0,95 |
| 10 | Clerosterol | (24S)-24-ethyl-Δ-5,25-cholestadien-3 ß -ol | 0,96 | 0,96 |
| 11 | ß -sitosterol | (24R)-24-ethyl-Δ-5-cholesten-3 ß -ol | 1,0 | 1,0 |
| 12 | Sitostanol | 24-ethyl-cholestan-3 ß -ol | 1,02 | 1,02 |
| 13 | Δ-5-avenasterol | (24Z)-24-ethylidene-Δ-cholesten-3 ß -ol | 1,03 | 1,03 |
| 14 | Δ-5-24-stigmastadienol | (24R,S)-24-ethyl-Δ-5,24-cholestadien-3 ß -ol | 1,08 | 1,08 |
| 15 | Δ-7-stigmastenol | (24R,S)-24-ethyl-Δ-7-cholesten-3 ß -ol | 1,12 | 1,12 |
| 16 | Δ-7-avenasterol | (24Z)-24-ethylidene-Δ-7-cholesten-3 ß -ol | 1,16 | 1,16 |
| 17 | Erythrodiol | 5α olean-12en-3ß28 diol | 1,41 | 1,41 |
| 18 | Uvaol | Δ12-ursen-3ß28 diol | 1,52 | 1,52 |
Figure 1
Gas chromatogram of the sterol and triterpene dialchols fraction of a lampante olive oil (spiked with internal standard)
Figure 2
Gas chromatogram of the sterol and triterpene dialchols fraction of a refined olive oil (spiked with internal standard)
