Improvement in the resolution of individualtrans‐18:1 isomers by capillary gas‐liquid chromatography: Use of a 100‐m CP‐Sil 88 column

Abstract

Doubling the length of a CP-Sil 88 capillary column (Chrompack, Middelburg, The Netherlands) from 50 to 100 m remarkably improves the resolution of individual trans-18:1 isomers from either ruminant fats or partially hydrogenated oils. Although the use of a 50-m column gives interesting results, it does not allow sufficient resolution of the trans-10 and trans-11 18:1 isomers. Moreover, the trans-6 to trans-9 18:1 isomers emerge as a single group of peaks, whereas the trans-12 isomer is only partly resolved from the adjacent trans-11 and trans-13 plus trans-14 isomers. With the 100-m column, the trans-9, trans-lO, and trans-12 18:1 isomers are almost baseline resolved from other isomers. However, with both columns, it is not possible to separate the critical pair of trans-13 and trans-14 18:1 acids which co-elute under a single peak. Despite this minor drawback, the 100-m CP-Sil 88 column appears to be of great interest for the separation and the quantitation of most individual trans-18:1 acids. Except for the use of argentation thin-layer chromatography, there is no need for complementary techniques, such as ozonolysis. This simple and powerful tool may be applied to ruminant fats, partially hydrogenated oils, and human tissue lipids. JAOCS 72, 1197-1201 (1 995).

Resolution Behavior of cis- and trans-Octadecenoic Acid Isomers by AOCS Official Method Using SP-2560 Column

“…3 are similar to the findings of a previous report 2, 19,20 . These orders are affected by the GC temperature.…”

“…For example, the fatty acid content of cis-4-C18:1 and cis-5-C18:1 isomers was 0.21 g per 100 g oil, while that of cis-6-C18:1, cis-7-C18:1, and cis-8-C18:1 isomers was 2.44 g per 100 g oil in PHVO Table 4 . Previous studies reported that minor cis-C18:1 isomers ranging from cis-6 to cis-15 except cis-9 exist in PHVO and milk fat 4, 14,19 . The cis-C18:1 and trans-C18:1 isomer peaks overlapped.…”

Conjugated Linoleic Acid (CLA) content of meat from three muscles of Massese suckling lambs slaughtered at different weights

“…Individual FAMEs were identified by comparison to a standards mixture of 37 Component FAME Mix (Supelco, Bellefonte PA, USA). The identification of isomers of C18:1 was based on commercial standard mixtures (Supelco, Bellefonte PA, USA) and published isomeric profiles (Wolf & Bayard, 1995). All methods using peak normalisation and which express the results in relative percentages of the area of the analysed peaks are subject to overestimation because the areas of small peaks are not considered.…”

Analytical methods for determination of trans-C18 fatty acid isomers in milk fat. A review

“…It should be noted that GC column efficiency is proportional to the square root of column length and the resolution is strongly influenced by the selectivity, therefore increasing column length will lead to appreciably higher resolution, and selectivity modification will affect significantly separation as well [12,30]. For instance, during the 1970's, the use of polar packed columns (such as SP-2340 or OV-275) did not afford separation of cis-18:1 fatty acids from trans-18:1 isomers, and even poorer quantitation of each of the positional isomers [13,23].…”