Did the laboratory provide you with enough information to calculate the amount of total trans and total cis fatty acids?

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Not right. For some fatty the geometrical configuration is not mentioned (e.g. for C20 fatty acids).

Not right. For the C20 fatty acids the geometrical configuration is not mentioned. For example, you don’t know if C20:2 are cis or trans fatty acids or a mixture of both.

Not right. Look at the chromatogram at the region between 35 and 42 minutes. There you can see that the cis and trans isomers are not completely separated. In practice the peaks at the right side of the diagram are mainly cis fatty acids and the peaks at the left side the trans fatty acids. However, because of the incomplete separation, usually the amount of trans fatty acids is underestimated.

Right. For some fatty acids the geometrical configuration is not mentioned. Sometimes you can predict the configuration of these fatty acids if you know which fatty acids are usually present in foods. Otherwise you have to ask the laboratory for more information. Furthermore, you can see that the cis and trans isomers are not completely separated. In practice the peaks at the right side of the chromatogram are mainly cis fatty acids [includes C18:1 (n-9) cis], and the peaks at the left side [left from C18:1 (n-9) cis] the trans fatty acids. However, because of the incomplete separation, usually the amount of trans fatty acids is underestimated, because more trans fatty acids of C18:1 elute with C18:1 cis than vice versa. In the laboratory output you can see that cis fatty acids are reported separately. Fatty acids with at least one bound with a trans configuration (also if there are one or more bounds with a cis configuration) are indicated as ‘trans sum’. So C18:2 (n-6) trans sum includes C18:2 (n-6) trans cis, C18:2 (n-6) cis trans and C18:2 (n-6) trans trans

With respect to this margarine: all fatty acids for which the configuration is not mentioned are cis fatty acids.

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yes, it is indicated which fatty acids have cis and or trans configuration, as in C18:2 (n-6) cis cis.

no, for some fatty acids the geometrical configuration is not mentioned (e.g. for C20 fatty acids).

no, because in the chromatogram you can see that the cis and trans isomers of C18 are not completely separated.

Here you see the results (chromatogram) of the fatty acid analysis of the margarine. Study this chromatogram together with the data in the excel file.