Use of an extremely polar 100-m column in combination with a cyanoalkyl polysiloxane column to complement the study of milk fats with different fatty acid profiles

A detailed dairy fat fatty acid (FA) profile can generally be achieved by gas chromatography using capillary columns with polar cyanoalkyl polysiloxane stationary phases (CPSP). However some compounds overlap and cannot be discriminated after a single run. In this work a new, extremely polar phase column (SLB-IL111) was used to complement the analysis carried out by a CPSP column. Separation of the FAs in a variety of milk fats using both a 100-m SLB-IL111 column and a 100-m CP-Sil 88 column was carried out and a more complete profile was established. The combination of results was useful to discriminate FA pairs, i.e., 10:1/11:0, cis-10 12:1/13:0, iso 17:0/trans-9 16:1, anteiso 17:0/cis-9 16:1, trans-16 18:1/cis-14 18:1, trans-11 cis-15 18:2/trans-10 cis-15 18:2 and trans-7 cis-9 18:2/cis-9 trans-11 18:2. Furthermore trans-8 and trans-13/14 18:1 isomers were also well discriminated. The use of both columns allowed detection in milk of some lactone and keto FAs.