RELATIVE POLARITIES OF NINE MODIFIED CYCLODEXTRIN COMMERCIAL STATIONARY PHASES IN GAS CHROMATOGRAPHIC CAPILLARIES

摘要

''Polarities'' of commercial modified cyclodextrin (CD) gas chromatographic phases were rated at 100 degrees C by the averages of retention indices for eight McReynolds' probe solutes, by the sequence and proportion of three, and by Delta C values for two of them. All nine CDs studied are above the low polarity of a fully methyl polysiloxane, and below the high values of a polyethylene glycol. Values from some CDs are similar to those of polar substituted polysiloxanes. Modifications of alpha-CD are of lower polarity than their corresponding larger CDs. Dipentyl-(hydroxy remaining)-CDs are of lowest polarity and hydroxypropyl-dimethyl-CDs the highest. Esterified-(dipentyl)-gamma-CDs fall between these groups, along with a supposedly fully methyl-beta-CD. Surprisingly, the butyryl ester seems to be more polar than the shorter chain propionyl one. These features can be seen from a triangular plot of retention index fractions of the sum of three McReynolds' probes.